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20 DECEMBER 2021

INCREDIBLE CLAIMS ON HEATING-SYSTEM EFFICIENCY
Reader John S. is the latest of many to seek my advice on assorted products which get glowing testimonials for saving fuel in heating systems. These fall into two categories: combustion enhancement (usually magnets); and waterside heat-transfer improvers (additives, air-removal devices, special stones and yes magnets).
Let's just reflect on what happens in a heating system based on hot-water circulation from boilers. Take combustion first. There is only a certain amount of chemical energy in the fuel, and with perfect mixing and exactly the right amount of oxygen in the combustion process, all of it is turned into heat. In practice we guarantee complete combustion by maintaining the burner correctly and running with some excess air. Diligent maintenance entails adjusting the air:fuel ratio with as little excess air as possible (evidenced by very low carbon monoxide levels in the exhaust). Under these conditions nothing we do to 'condition' the fuel can increase the amount of energy that's released. But even if we could reduce the stack oxygen level from say 7% to 5%, that only wins a 1% fuel saving.
Now let's look at heat transfer. Of the heat that the boiler produces, part goes up the chimney, a little is lost in standing losses, but most is transferred into the circulating water. The more we can transfer into the water the more efficient our heating system is, so keeping heat-transfer surfaces clean is paramount. Increasing the useful heat transfer implies reducing the heat in the exhaust, and this will be evidenced by lower exhaust temperatures. Diligent maintenance includes getting exhaust temperatures down to the lowest level practicable. On a gas-fired boiler a reduction from 200C to 150C wins you about 3% in savings but because most of the thermal resistance is on the gas side it is difficult to see how improved water-side heat transfer could ever be credited with the savings of over 10% that are often claimed.
And that is always the challenge to use with suspect offers: where is all this wasted energy going that you are going to save?
My argument is that ordinary diligent maintenance should leave you little or no headroom for further savings. Which brings me to testimonials. If somebody says that product X cut 14% off their fuel consumption, they are as good as admitting that they were previously using 16% more fuel than would have been necessary with proper maintenance. Ouch.
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22 NOVEMBER 2021

RATIONAL PLANNING FOR HEAT DECARBONISATION
Many organisations are starting to plan trajectories towards net zero, and specifically thinking about replacing gas or oil heating with something else such as heat pumps. Some will blindly stumble into like-for-like replacements. Others, recognising that their existing boilers might be oversized, will commission surveys and building simulation models in order to establish what heating capacity their building actually needs. This could reduce the cost of replacement when the time comes.
I'm going to suggest that there's a quick and cheap way to find out a building's actual peak heat load, using weekly or monthly consumption data and corresponding degree-day figures. Indeed, for someone who already operates an energy monitoring and targeting system the job is already almost done because they will have a regression model for each building relating consumption to degree days.
To show how it works let's imagine a building which has a fixed weekly consumption of 2,000 kWh per month and variable consumption of 180 kWh per degree day. Taking its base-load consumption first, as there are 730 hours in an average month, the fixed consumption equates to an average continuous power of 2,000/730 = 2.74 kW. Regarding the variable component of demand, 180 kWh per degree day is 180/24 = 7.5 kWh per degree hour, which is the same as 7.5 kW per degree (of temperature difference between outside and the building's balance point). So suppose we take our design coldest day as being, say, 17C below the balance point. Average input fuel power requirement on that day will be 2.74 + (7.5 x 17) = 130 kW. Finally we'd need to make an assumption about the existing system's efficiency to turn that peak input power into peak heat output of 130 x (say) 80% = 104 kW.
There are a couple of caveats here. Firstly, the 104-kW heating system would need to run continuously to meet demand on the coldest day and would have limited reserve for preheating the building in milder weather. Adding a margin of capacity for boost could be prudent, although in a well-insulated and airtight building the penalty for longer preheat times is not necessarily significant. We should also bear in mind that with a carbon-neutral public electricity supply, it would be environmentally sound to use direct electric heating to meet peak demands rather than investing in heat-pump capacity that is unused most of the time.
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8 NOVEMBER 2021

A LATENT PROBLEM?
When you burn natural gas, one of the products of combustion is water vapour and unless you condense that vapour from the exhaust, 9.6% of your fuel's energy content is condemned to be lost as latent heat. That's what makes condensing boilers attractive as long as you can get the exhaust temperature down below 60°C. Which you achieve by having bigger heat emitters that return the circulating water at a low temperature.
With other hydrocarbon fuels the greater preponderance of carbon reduces the amount of water vapour emitted so the scope for capturing latent heat is reduced. But what if the UK gas grid were decarbonised by converting it to hydrogen? In that scenario, water vapour will be the sole product of combustion and the proportionate loss in latent heat will be higher (over 15%, in fact). This implies that for many heating systems, simply converting existing gas appliances may not be enough. To get reasonable fuel efficiency you may need to increase the sizes of heat emitters to drop the system return temperature well below the flue-gas dewpoint. Sound familiar?
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1 NOVEMBER 2021

A DIPLOMA FOR SNAKE-OIL SALESMEN?
What would the exam questions look like if you were testing people whose job is to sell bogus energy-saving technologies? Perhaps something like this:
Instructions: extra points will be awarded for evading questions.
Question 1: you are claiming that your central-heating additive enables the system water to heat up faster. Explain the benefit in cases where the water is circulated continuously at a constant temperature.
Question 2: explain how, in multi-foil insulation, radiant heat penetrates the outer reflective layer to be reflected by the inner layers.
Question 3: you are selling a block of gel to encase the thermostat sensor of a freezer store. Explain how this prevents the stored food thawing on the surface before the sensor registers the rise in temperature.
Question 4: in a refrigeration circuit, explain how injecting heat from a solar panel increases cooling power without increasing electricity demand.
Question 5: a customer complains that your voltage optimisation unit continuously dissipates 1.5% of her site's maximum load as standing losses. Explain why this did not need to be mentioned in sales promotions.
Question 6: you are selling a magnet to fit on the fuel line of a heating boiler. Explain why its effect on performance should not be tested using recognised conventional methods.
Answers: Q1: "Sorry, I'm not a scientist"; Q2: "Sorry, I'm not a scientist"; Q3: "Sorry, I'm not a scientist" (enough answers - Ed.)
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29 SEPTEMBER 2021

PIPEWORK INSULATION
Prompted by a question from reader Nick S., I have been delving into the question of pipework insulation and its effectiveness. Older readers steeped in the lore may recollect the Government's "Fuel Efficiency Booklet 8" which contained a family of charts that enabled you to look up the heat loss per linear metre for various insulation materials, pipe diameters, and surface temperatures. But it's actually quite hard to find online tools to do the job comparing insulated with uninsulated pipes like those old charts do, and annoyingly, almost every guide you see lists pipe sizes by 'nominal bore' when all the energy surveyor can measure is the outside diameter.
So I have put together an on-line calculator. When you use it what you immediately see is that the savings are not terribly sensitive to how much insulation you apply, which makes it reasonable to choose a standard thickness according to BS 5422. The savings are, however, extremely sensitive to the assumed bare-pipe heat loss, which is very hard to estimate. Published tables need to be treated with caution not least because they relate to horizontal pipes in still air with nothing in close proximity. A vertical pipe indoors next to another running up a wall will have much lower uninsulated loss than a single horizontal pipe in the open air. Bear this in mind when using the estimator.
The link to the new pipework insulation tool is at http://vesma.com/tools.
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27 SEPTEMBER 2021

YOU COULDN'T MAKE IT UP
I have seen a network server installed in a plant room for the want of anywhere else to put it, but never with air conditioning to counteract the heat coming off under-insulated heating plant. But that's what one reader found in two buildings he surveyed. His story won this month's 'Star Spot' award and Ł50 has gone to his nominated charity, Macmillan Cancer Support. If you have a favourite charity and a crazy story about needless energy waste, please enter the contest here.
'NETTING BACK'
Although regression analysis is popular in energy management as a method of deriving expected-consumption formulae, it is not without pitfalls especially when there are two or more driving factors at play. Regression is only a statistical guess at the relationship. Because it lacks physical insight it can produce incorrect, implausible or even bizarre results even when the thing you are analysing has behaved consistently in the past (which many energy-using systems have not). That's why when multiple regression analysis looks like it is appropriate I always recommend using first-principles calculations, empirical tests, or reasoned estimates for as many of the coefficients as you can, relying on statistics to analyse as few of the variable factors as possible.
Adopting this hybrid strategy entails a process which I explain, with examples, at EnManReg.org/netting-back.
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20 SEPTEMBER 2021

PERSUASION, COMPULSION, COLLABORATION AND SABOTAGE
Behaviour-change entails persuasion, and for the energy manager wanting some inspiration and guidance I think there are few books better than 'Yes - 50 Secrets from the Science of Persuasion' (or 60 secrets in the later edition). The book is a compendium of short articles describing persuasion techniques and the science behind them, and as well as the tips and tricks it contains, I found it useful for warning me off things which sound like good ideas but actually aren't.... Cash rewards being one. Definitely worth a small outlay on a used copy.
One of the ways we try to get employees to collaborate in energy-saving initiatives is to involve them in developing ideas so that they 'own' the programme. But in the view of some experts this can backfire, partly because consultation may suggest that management actually don't know what needs to be done. Meanwhile in organisations which have a strong command culture, a consultative approach may send a signal that the issue is not important. In such organisations a 'just do it' approach may be more effective.
Cultures and attitudes vary from country to country as well, and this can have an impact on workforce collaboration. In western, educated, industrialized, rich and democratic societies, most people think it's a good thing to co-operate and we take a dim view of free-loaders. Some years ago, however, an international research project at Nottingham University discovered a phenomenon called “anti-social punishment” in which freeloaders punish co-operators. Russia, Saudi Arabia and Greece were among the countries where this tendency was observed. What this means is that readers who advise or work for multinational companies shouldn't take methods developed in one country and expect them to work everywhere else.
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20 AUGUST 2021

CUTS ELECTRICITY BILLS, CURES INSOMNIA; WHAT'S NOT TO LIKE?
Reader Jill D. afforded me an hour or two of innocent amusement when she alerted me to a device called 'Voltex'. The product is a little mains plug-in unit which claims not only to save you energy as soon as it is plugged in to a wall socket, but to progressively reduce the electromagnetic radiation in your home or office over the course of a couple of months. Hoorah! No more tinfoil helmets for us after October.
There are a few plug-in power savers doing the rounds and most contain not much more than a capacitor and a green LED in series with a resistor. Voltex supposedly contains 'patented technology' but when I asked them for the patent numbers they said "the patent is a very complex thing, so in order to be able to sell in multiple places, it’s been decided to risk for the expansion". When I pointed out that this was devoid of meaning and pressed them for an answer, they said "For security reasons, we cannot disclose ... the patent number". So I think we can take it that they don't actually hold any patents. Even if they did, it wouldn't imply that their product worked, and in fact in the U.S. where they originate, you can patent something that doesn't even obey the known laws of science.
Like many scam products, Voltex is marketed with testimonials. Kevin Holmes from London, Brenda Shearer from Leeds and Thomas Crowder from Essex all state how much money they have saved; although strangely they all quoted their savings in dollars.
There are two embedded videos on the Voltex web site, but neither relates to the advertised product. One is about the 'Power Perfect Box', a clunky thing (probably also a capacitor; who knows?) costing about a thousand dollars that needs wiring into a main distribution box. The other is a product called Greenwave which supposedly eliminates 'dirty electricity' and cures insomnia, inflammatory conditions and so on.
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19 JULY 2021

DIFFERENT APPROACHES TO ENERGY WASTE DETECTION
When we need to compute expected consumption as part of an energy monitoring and targeting scheme, we usually reach for a straight-line regression model, perhaps based on weekly observations, as the default method. But there are other approaches. Last Thursday as part of my "Energy Conversations" series I interviewed James Ferguson about the work that his company has been doing for organisations with extensive chains of similar buildings. He uses machine learning methods to characterise the fine-grained diurnal pattern that each building should exhibit under given weather conditions, and this gives him an alternative handle on how much each should be using on a daily basis (together with some rich diagnostic information).
Thinking about what we can do with large quantities of real-time data reminded me of a job many years ago setting up energy monitoring and targeting for a set of nine distillation columns. Being a highly-automated process plant it was well-provided with temperature and flow measurements which were being logged at one-minute intervals. But the process was a little complicated: it was handling a mixture of three fluids, one of which was the desired product while the other two were volatile solvents which had to be boiled off. How to calculate expected steam consumption? My solution was to sample the flow and temperature data at 20-minute intervals, and using the reported blend proportions, compute the latent heat implicitly absorbed by each solvent and the increase in sensible heat. Basically school physics. The 20-minute estimated heat demands were aggregated into a weekly expected consumptions and could then be compared with actual weekly steam use.
My primary purpose was to detect and quantify deviations from expected steam consumpton. Excess consumption was always a risk, and likely to arise because of degradation or fouling of the internals. Distillation columns with sufficiently-costly excess steam use could then be taken out of service early for maintenance, with production shifted to the most energy-efficient alternative units.
The columns were high-temperature, high-pressure vessels that ran continuously for nine months at a time between scheduled maintenance shutdowns. There was potentially a lot of money to be saved by postponing maintenance where it was safe to do so, but there was no way of directly observing them internally. So the owner had previously spent tens if not hundreds of thousand of pounds on AI-based condition monitoring systems, analysing the plant data, in order to determine if each column was healthy. This had not proved effective. However, my energy monitoring and targeting scheme gave them condition monitoring free of charge. Any internal changes within a column would change its energy demand characteristic for the worse, but if a column continued to consume steam in line with expectations, it could only be because it was internally intact and did not yet need to be stripped down.
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12 JULY 2021

ZOOM VERSUS VROOM
Loyal reader Paul C. asked if I'd ever seen any articles about the climate impact of remote meetings, and I hadn't, so I decided to work it out for myself. Here's the comparison of emissions from remote meetings with those from travelling to attend in person...
We'll start by estimating the energy intensity of data communications. We know from an Ofcom study that in 2018 the average UK fixed broadband connection was using 240 GB per month, and if we assume Ł30 per month was the typical tariff, that works out at Ł0.125 per GB. Now let's assume that this price covers the operator's costs and that, pessimistically, 50% of that cost is for electricity which they were buying at (say) Ł0.15 per kWh. This implies an energy intensity of Ł0.125 x 50% / Ł0.15 = 0.42 kWh per GB.
But how much data is there in a remote meeting? Fortunately we can get a good direct estimate from the sizes of session recordings. My two-hour on-line events have typically resulted in recordings of around 500 MB, which must be the equivalent of all the data broadcast to each participant (as a sense check, that's 250 megabytes per hour, or about 0.55 megabits per second bandwidth). To be conservative let's add as much again for return traffic from each participant, giving a total of 500 MB (0.5 GB) per hour per participant.
At 0.42 kWh per GB that implies 0.5 x 0.42 = 0.21 kWh per participant-hour.
This only accounts for the communications element. To be fair we need to add the cost of central data processing and to do that I'm firstly going to guess that the server consumes 100 watts for the purposes of processing the meeting. Secondly I'll assume that the meeting has four participants. That would imply 0.025 kWh per participant-hour, bringing the total to 0.235. The fact that it's a small correction means the conclusions aren't very sensitive to the number of participants. If we assume a grid carbon intensity of 0.3 kgCO2/kWh we arrive at emissions of 0.235 x 0.3 = 0.07 kgCO2 per participant-hour.
How does that final figure compare with car travel to the meeting? The average car in the UK emits about 0.12 kgCO2 per km, so attending an hour-long remote meeting equates, in emissions terms, to 0.07/0.12 = 0.58 km of car travel. Case closed.
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28 JUNE 2021

EQUIPMENT FOR ENERGY SURVEYS
Top of my list for energy survey equipment is of course a mobile phone because it's useful as a camera (including as a means of reading inaccessible rating plates or meter dials), it will stand in for a torch, and its stopwatch function can be handy too, for example to estimate the load factor of intermittent on-off plant. You can use it just as a phone to co-ordinate 'drop tests' where one person does spot meter readings while another turns major loads on and off, and as a browser to gather information on unfamiliar plant and equipment. I have a plug-in infra-red camera for mine which is useful for detecting and recording hot or cold spots.
Next is a digital thermometer with type K thermocouple probes. Mine operates in the range –50 to 200°C with 0.1 °C resolution, but it can be useful to have another for up to 500°C with 1 °C precision. For high-temperature applications a robust probe is needed but below 100°C, say, a bare thermocouple junction can be used. They are very good for air temperature because they respond quickly, but they can also be attached to pipework under a wad of insulation to get a reasonable measurement of flow temperature. Thermocouples can be left in place and read from time to time by connecting the instrument when required.
I usually carry a non-contact thermometer to give approximate temperatures of inaccessible surfaces, an anemometer to measure air velocities especially in supply and extract ducts, and sometimes a digital relative humidity probe.
For extended tests one can deploy miniature data loggers which record temperature, relative humidity, voltage, or pulses from a variety of sources including movement sensors (logging occupancy levels) or even improvised temporary contacts on valve linkages and other moving equipment.
I carry a light meter capable of working over a range of 50-2000 lux. It is a cheap one calibrated for incandescent light only, so results are only indicative; and for a proper lighting survey one would use a more expensive model which can be switched to compensate for the different light-source characteristics.
For electrical power measurements a plug-in power meter can be used to check the consumption of appliances under 3kW rating, but the chances of finding any worthwhile savings at this level are slim. A proper electrical demand profile recorder will be needed for loads big enough to offer significant opportunities for saving. A three-phase instrument with a mains lead gives you the full picture including power factor, while a much cheaper 'current clamp' meter with data logging will allow you to determine load factors on intermittent equipment.
A non-contact tachometer is used measure motor speeds, which in the case of induction motors allows one to estimate their mechanical output by reference to their rated slip speed at full load. By the way, do not bother with stroboscopic tachometer phone apps; most don’t work at high enough frequencies, plenty don’t work at all and they all need to be used in darkness.
Other than that I would carry a torch, a pocket tape measure, a manhole lid lifter (for access to water meters) and meter compartment keys.
For some people a combustion analysis kit, although relatively expensive, is a good long-term investment because it enables poor combustion to be detected through regular checks. Always choose one with carbon monoxide measurement. If using oil or solid fuel, you will also need a smoke pump.
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12 APRIL 2021

FROST PROTECTION SYSTEMS
For my UK readers and others in similar climates April may seem a strange time of year to be talking about frost-protection systems but a flurry of overnight snow reminded me that it's never the wrong time. Malfunctioning frost protection can cause avoidable energy waste all year round.
I recall when I was energy manager at Lambeth there was a fuss because the landlord's electricity bills in one of our blocks of flats had inexplicably shot up and theft was suspected. The truth turned out to be that the access ramp to the basement car park had electric de-icing heaters that had started running continually because of a faulty thermostat. Removing the fuses fixed that. When I later told this story during an in-company training course at an office block in Swindon, one of the group said that he'd come to work one rainy morning and noticed that all the front steps were dry (except one). Same problem: electric de-icing heaters that they didn't even know they had, running all the time at a cost, they told me, of several thousand pounds a year. And the one wet step? Its embedded heater element had burned out, so as well as losing a lot of money they had also lost service.
When reader Philip C. started as energy manager he found that a full 40% of the electricity used in his head office was due to electric frost-protection pre-heaters running unnecessarily in their air-handling units... And so it goes on...
It could be happening to you. Frost protection is a high-risk service when it comes to hidden, unexpected energy waste. It should always feature in building energy surveys, and it needs a mention in all staff awareness briefings. But for long-term protection against the random onset of this kind of fault nothing beats an effective energy monitoring and targeting scheme.
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1 APRIL 2021

MAKE APPLIANCES RATE AGAIN
The Government is keen to nudge people to choose more energy-efficient household appliances and for many years has helped consumers by getting manufacturers to put energy labels on products, typically rating them A to G to signify that they are more or less energy efficient (a concept too complex for most people to grasp). And for people who find the concept of A, B, C etc too complex to grasp they add coloured arrows of different lengths. The shorter the arrow, the higher the efficiency.
The march of progress has caused problems because many products are now more energy efficient than the bureaucrats foresaw. They are crowded into the ‘A’ rating band, and unfortunately there are no letters before A in the alphabet so ‘A’ is now sometimes subdivided into A+, A++ and A+++. However, most people find this concept too difficult to grasp, so the efficiency scales for affected appliances will be regraded A to G so that for example what was A++ will now become B, A will become D, and so on (they will take F off).
Meanwhile a rival scheme for washer-dryers caught my attention. This gives a three-letter rating signifying the efficiencies of washing, spinning, and tumble-drying parts of the cycle. Thus a machine that is in the most efficient category in every respect gets an ‘AAA’ rating. With a bit of forethought they could have started later in the alphabet to allow room for future improvement. They could even have helped people by using the sequences W to Z for Washing, S to V for Spinning, and D to G for Drying. Then a machine currently labelled ‘ABC’ would become ‘WTF’.
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25 JANUARY 2021

D IS FOR DRIVING FACTOR
A fundamental part of effective energy management is the routine comparison of actual consumptions with expected values, and those expected consumptions need to be calculated as accurately as possible. Underlying this is the idea that consumptions vary in line with the weather, production activity levels, available daylight, mileages or other such measureable factors, with formulae being established that relate each consumption to the relevant factor or factors.
In some literature you will see these factors referred to as ‘independent variables’ or ‘relevant variables’. They do indeed need to be relevant and independent measurements, but the term ‘driving factor’ better describes what they do: they are the things whose day-to-day variation drives variation in energy consumption.
As well as causing variation in consumption and itself routinely varying through time, a driving factor needs to be expressible as a numerical value. For energy-intensive products this is often as simple as counting the throughput quantity; where applicable, weekly hours of darkness and vehicle mileages are equally straightforward. Dealing with the weather is more complex. The most significant variable here is outside air temperature. However, the response of a heating system to variation in temperature is not linear because there will always be an outside temperature above which demand is zero. The universal solution to this problem is to track the outside air temperature more or less continuously and convert the data into a measure called the degree day value which can be reported, as a single number, at weekly or monthly intervals (typically). A building's heating fuel consumption can be expected to correlate with degree-day values for the region in question.
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22 JANUARY 2021

C IS FOR 'CUSUM'
‘Cusum’ is a charting technique which originated in the world of quality control, and was first applied to energy management in the 1980s. Like so much in monitoring and targeting it relies on having good estimates of expected consumption, and the term ‘cusum’ stands for ‘cumulative sum of deviation from expected consumption’.
Suppose you have a weekly* monitoring and targeting regime. Thinking about one individual stream of consumption, you will have actual and expected consumptions each week and they will differ. Sometimes the difference will be negative, sometimes positive, and the magnitude of the differences will vary. Now imagine what the cumulative sum of those differences will look like as time goes by. If there is no bias either way, the random positives and negatives will tend to cancel out and the cusum (for that’s what it is) will maintain an approximately constant value. This will manifest itself as a generally horizontal trend when plotted as a time-series graph.
Now imagine what happens if performance of the thing you are monitoring changes. This will introduce a bias in the differences between actual and expected consumption. If performance has got worse, the cusum trend will bend upwards; if there was an improvement, it bends downwards. Looking at a time-series chart of the cusum value will show you when past changes in performance occurred.
But it’s not just the dates of past changes that we are interested in. Cusum separates the history of performance into episodes of good and bad performance. By an 'episode' I mean a succession of weeks - say five or more - which appear to behave similarly. Analysing the ‘good’ episodes in isolation enables us to tune the formula for expected consumption so that in future we will always be assessing actual consumption against the best it could have been. In this way, cusum gives us tough-but-achievable targets backed by evidence. Conversely, analysing poor-performance episodes gives us evidence about the nature of any adverse behaviour, which is invaluable diagnostic information.
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19 JANUARY 2021

B IS FOR BASELINE
To most people ‘baseline’ energy consumption means the actual quantity of energy that was used over a certain reference period. Quite often, annual figures are used and subsequent annual consumption is then gauged against this yardstick (ideally with adjustments to account for the influence of the weather or other factors). There is a subtly better way, however.
Best practice in energy monitoring and targeting starts with finding the formula that relates consumption to one or more relevant driving factors (weather, product output, etc). Once you have such a formula you can estimate expected consumption over any interval you choose, giving you the ability to check that the quantities used over a week (say) were reasonable given the prevailing conditions.
As time goes by, energy-saving measures may be introduced. When that happens the related expected-consumption formulae need to be revised to reflect the new achievable performance. In that way any subsequent loss or inefficiency shows up properly because we can feed current driving-factor figures into the current formula to work out how much we should have used. But we can also feed the same numbers into the original formula to work out how much we would have used in the absence of our energy-saving measures. That original formula is called the historical baseline formula: it enables us to evaluate progress at any interval in a way that automatically adjusts for changes in the influencing factors. Thinking in terms of baseline formulae is therefore far superior to using baseline quantities.
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15 JANUARY 2021

A IS FOR AVOIDABLE WASTE
Monitoring and targeting is about more than passively tracking trends and allocating spends. In large part it should be about detecting abnormal patterns of use and thereby exposing ‘avoidable’ consumption—energy used in excess of what was strictly required given the prevailing circumstances. To do this properly you need an accurate way of calculating expected consumption, usually by means of a formula based on measurements of relevant driving factors such as how cold the weather was, or what your levels of output or activity were.
Avoidable waste tends to be associated with human error, minor control malfunctions, substandard maintenance and other faults that are quick, non-disruptive and cheap or even free to correct. It is always unexpected and often hidden, so many energy users end up living with excess costs and emissions. It need not be so: once you can gauge actual consumptions against accurate estimates of expected consumption you will be able to spot that it has happened and get something done about it.
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14 DECEMBER 2020

ORDER, ORDER
If you are contemplating two or more energy-saving measures on the same installation it is definitely worth considering whether they interact. For example a radical refurbishment to a building might entail insulation and new, higher-efficiency heating boilers. The altered thermal characteristics of the building fabric may well affect the size of the replacement boilers so if your budget will only stretch to one measure at a time, you should do the insulation project first.
The classic interaction is in the domain of lighting. Are you considering improved controls and relamping with more energy-efficient lights? Either of those projects will compromise the economic case for the other because it would reduce the baseline consumption and hence the amount that will be saveable by the other option. This is not to say, however, that there won't be special cases where you would do both. Changing from high-intensity discharge lamps to LEDs will result in savings, albeit relatively small on the face of it; the big gain here comes from the ability to turn LEDs on and off at will, so in this specific instance the change of lamp type actually facilitates automatic control that would not previously have been possible.
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4 NOVEMBER 2020

INFRA RED THERMOGRAPHY
When a relative of mine arrived at her dentist's yesterday they tried to measure her temperature with a non-contact thermometer but her forehead was too shiny. I mention this because non-contact thermometers are useful bits of kit for energy surveys (how else could you quickly establish the temperature of a high ceiling?) but they are prone to error, with the emissivity and reflectivity of the measured object being two major sources of error. Infra red sensors actually measure radiant heat flow and infer the temperature of the subject body by assuming it has a certain emissivity. If the true emissivity is lower than assumed, the heat flux will be lower for a given temperature and the thermometer will deduce that the temperature is lower than it really is. Meanwhile if the subject body is at all heat-reflective the thermometer will pick up some reflected heat from nearby hotter surfaces, or lose some heat to colder ones, introducing positive or negative error as the case may be. For these reasons (and others I left out for simplicity) non-contact thermometer readings should be treated with caution.
Thermal imaging cameras are now sometimes used for energy surveys, where similar considerations apply. However, as long as your main interest is the pattern of temperature over a surface or in a scene - that is, hot or cold spots - it is generally safe to assume that errors will tend to be systematic and thus not interfere with interpretation of the results as long as you take certain precautions.
Where I have some doubt is the idea that thermographic surveys can be used to quantify heat flow through walls and so on. Let's think how such an estimate would be arrived at, given that all we could know is the ambient air and wall-surface temperatures. The layer of air close to the wall offers some thermal resistance (typically we might assume 0.06 m2K/W), so if the wall surface is, say, 0.9 degrees above the ambient temperature the heat flux must be 0.9/0.06 = 15.0 W/m2. The problem with this is that there is considerable uncertainty in the surface-layer resistance (it is significantly affected by air movement) and there is no way, given what we said earlier, that the wall surface temperature could be established with sufficient accuracy to measure such a small differential. Moreover, the illustration I gave was for an uninsulated wall. For an insulated structure the surface-to-ambient-air differential will be even smaller and the errors overwhelming.
So if you see claims that an infra red survey can tell you how well a structure is insulated, treat them with skepticism.
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19 OCTOBER 2020

REALITY CHECKOUT
Sainsbury's, one of the UK's leading purveyors of greenwash, is procuring 1,200 pallet trucks which it claims are 'powered by kinetic energy'. It is highly reminiscent of their hilarious 'kinetic plates' project in Gloucester in 2009 where they said they were harvesting energy from traffic to power their tills. Reader Ian B., who tipped me off (thanks Ian), thinks it sounds like perpetual motion.
So what is going on? None of the news outlets that republished the story questioned the claim or tried to explain what it might mean. However, there's a clue in a mention of lithium-ion instead of lead-acid batteries: my guess is that most likely these trucks are just using regenerative braking to help recharge their batteries (lead-acid batteries cannot tolerate the high charging currents that result from full braking effort). The reason that pallet trucks benefit from regenerative braking is that they need to stop or decelerate so frequently. Underground trains likewise; they have been able to use the principle for ages because their power supply network can absorb high braking currents.
We're assured the initiative is saving 'enough ... to power 700 homes' which implies that each truck is saving 2,000 kWh per year. That's a modest but respectable saving, though it hardly equates to powering the whole truck.
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7 SEPTEMBER 2020

READY, STEADY, WASTE…
When I was an energy manager in local government the start of the new heating season was prime time for energy waste. One factor was that there would have been a programme of maintenance carried out over the summer and invariably there would be cases where heating system controls, overridden to enable testing, had not been put back to ‘automatic’. Or maintenance could be slack: for example, to save time, burners on some boilers would have been adjusted conservatively with too much excess air. Either of these common faults leaves a legacy of avoidable excess consumption.
On heating with adaptive optimum start (a common feature) there’s also a right and wrong way to stand the system down for the summer. You must put the optimiser into ‘holiday’ mode. If you just manually turn off the boilers at their local control panel your optimiser will start extending the preheat boost period as the weather get colder, not realising that its failure to achieve required conditions on time is caused by there being no heating. Once the boilers are enabled again, fuel will be wasted through premature start-up until the device has adapted back to normal operation.
Anyone managing a substantial estate should have effective exception reporting in place to detect such hidden unexpected excess energy consumption, whatever the cause. That is why you need an effective monitoring and targeting regime (complemented, where heating systems are concerned, with appropriate degree-day data).
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24 AUGUST 2020

ENERGY AUDITS AND SURVEYS: RULE OF THREE
Energy surveys and audits - deliberate studies to find energy-saving opportunities - can be done with three levels of depth and thoroughness, can look at three broad aspects of operations, and will generally adopt one of three approaches.
Let's take depth and thoroughness first. Level 1 would be an opportunity scan. This typically has a wide scope, and is based on a walk-though inspection. It will use only readily-available data, and provide at most only rough estimates of savings with no implementation cost estimates. It will yield only low-risk recommendations (the “no-brainers”) but should identify items for deeper study.
Level 2 (detailed survey) could have a selective scope, based perhaps on the findings from a Level 1 exercise. It is best preceded by a desktop analysis of consumption patterns and relationships, which means first collecting additional data on consumption and the driving factors which influence it. On-site measurements may be required. It should yield reasonably accurate assessments of expected savings but probably at best only rough cost estimates. It can therefore provide some firm recommendations relating to 'safe bets' and otherwise identify possible candidates for investment.
Level 3 is the investment-grade audit. This may have a very narrow scope - perhaps one individual project - and could demand on-site measurement and testing. It will involve sketch designs and feasibility studies, with accurate assessments of expected savings, realistic quotations for implementation, sound risk evaluation and (I would recommend) a measurement and verification plan
Next we will look at the three broad aspects of operations that the audit could cover. These are 'technical', 'human factors', and 'procedural'.
Technical aspects will encompass a spectrum from less to more intrusive (starting with quality of automatic control and set points through energy losses to component efficiencies). In manufacturing operations the range continues through process layouts, potential for process integration and substitution of alternative processes.
Human-factors aspects meanwhile will cover good housekeeping, compliance with operating instructions, maintenance practices, training needs and enhanced vigilance.
Thirdly, procedural aspects will include the scope for improved operating and maintenace instructions, better plant loading and scheduling, effective monitoring and exception handling, and ensuring design feedback.
The final three dimensions relate to the audit style, which I characterise as checklist-based, product-led, or opportunity-led.
The checklist-based approach suits simple repetitive surveys and less-experienced auditors.
Product-led audits have a narrow focus and exploit the expertise of a trusted technology supplier. Because the chosen focus is often set by advertising or on a flavour-of-the-month basis, the risk is that the wrong focus will be chosen and more valuable opportunities will be missed. Or worse still, the agenda will be captured by snake-oil merchants.
Finally we have the 'opportunity-led' style of audit. This is perhaps the ideal, although not always attainable because it needs competent auditors with diverse experience and will include the prior analysis and preliminary survey mentioned earlier. It differs through being open and wide-ranging in its scope with some effort to prioritise its areas of focus in an objective manner.
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13 JULY 2020

CHILLER PERFORMANCE
On one of my current projects I am collecting electricity input and cooling output data on a large chiller installation and, of course, using regression analysis to establish the relationship between one and the other. This has revealed tens of kilowatts of fixed background consumption (presumably fans, pumps, and other ancillary gear) and a gradient of about 0.25 kWh/kWh, signifying a coefficient of performance (CoP) of 4. It is important to separate out the background consumption like this in the calculation of CoP because it distorts the picture. The effect is exactly the same as the distortion you get by using kWh per tonne as a performance metric: at low output, the overall ratio is inflated.
You can also estimate the theoretical CoP as follows. Remember that a vapour-compression refrigeration loop has a hot side (in the condenser, which is at the compressor discharge pressure) and a cold side (in the evaporator, which is at compressor suction pressure). If we call the hot and cold refrigerant temperatures TH and TC respectively, the cooling CoP is given by TC/(TH-TC). These must be absolute temperatures, not Celsius. Real-life CoPs are lower, maybe 60% or so of the theoretical figure. You can get values for TC and TH by looking at the suction and discharge pressures on the machine. Because the fluid is boiling or condensing as the case may be there is a direct relationship between pressure and temperature for a given refrigerant and you can look up the temperatures using one of the manufacturer's online tools, or a table such as the one I have posted on my web site. The discharge pressure is of particular interest. If, on an air-cooled system, it implies a condenser temperature significantly above the ambient air temperature, you have an opportunity.
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11 JUNE 2020

CASTING LIGHT ON LUMINOUS EFFICACY
My piece in the last newsletter (8 June) comparing LEDs with obsolete low-pressure sodium lamps (which can give more lumens per watt) caused reader Simon S. to question why so many old street lamps are being replaced with LEDs. I suspect councils change to LEDs because (a) their maintenance costs are lower and (b) the electorate believe them to be more efficient. But there can be genuine energy benefits because LEDs have no warm-up time or restrike delay, meaning they can be automatically turned on and off. They can also be run at low power (our streetlights do that in the dead of night). These features are advantages compared with pretty well all high-intensity discharge lighting.
LEDs' colour appearance is of course much more acceptable than the monochromatic sodium yellow, but it is disappointing to find that the directional qualities of LEDs are not exploited, so light is sometimes wasted spilling out in all sorts of useless directions (as reader Mike H. observed).
Meanhwile thanks to Mike B. who challenged me for saying that tungsten lamps emit UV (which in significant doses would give us all skin cancer). Their UV output is completely negligible, so if you ever see one, no need to exercise social distancing.
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8 JUNE 2020

LUMINOUS EFFICACY
"Energy efficiency" means useful energy out divided by total energy in. What we mean by 'useful' output is usually straightforward, be it mechanical energy from a motor or useful heat from a boiler. But lighting is a little odd because although we know the output is light and heat, not all the light is necessarily useful - only the wavelengths that we can see. The 'luminous efficacy' of an electric light source is the ratio of the visible light output only (in lumens) to total electricity input (in watts).
While current LED lamps achieve over 100 lumens per watt (lm/W), there is an old technology, low-pressure sodium, which can reach 150 lm/W or more. How so? The answer is that the sodium lamp emits all its light at just one wavelength (recognisable as yellow-orange) with no spread into non-visible parts of the spectrum. Other light sources cannot do that, and in fact a tungsten filament lamp emits 95% of its light as infra-red or ultra-violet, which are of no use.
The penalty that you pay for good energy efficiency is poor colour rendering. So under low-pressure sodium lighting it is simply impossible to discriminate between different hues. For good colour rendering you need light over a wide spectrum, but then you're very likely to lose some energy as non-visible radiation.
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1 JUNE 2020

NOT WHAT YOU EXPECTED?
Computation of 'expected' consumption is at the heart of routine energy management because it provides a gauge against which to assess actual measured quantities. For normal routine exception reporting, expected consumptions are derived using formulae related to the weather, product throughput, mileages driven, hours of darkness or whatever else are relevant driving factors. However, there are variations on the theme that can be helpful in other circumstances. So for those who aren't familiar with them let me introduce three bits of jargon that I think you should know about...
1. ENERGY PERFORMANCE COEFFICIENT: this is the RATIO of actual to expected consumption. A value of one signifies as-expected behaviour; greater than one suggests adverse performance, and less than one implies improvement. It is therefore potentially useful as a performance indicator in its own right but is better used as a way of adjusting other more traditional performance indicators to remove the distortions caused by the weather, changes in prevailing production levels, etc.. It would normally be used on a weekly cycle or something of that order.
2. PERFORMANCE DEFICIT: this is the DIFFERENCE between actual consumption and what it would have been if the building, process or vehicle had operated at 'yardstick' efficiency (however you choose to set that). Typically the performance deficit is worked out on an annual basis but it can be done at any interval; its purpose is to rank opportunities for improvement when there are a lot to choose from, and for that purpose the deficits are usually converted into cash value. It is superior to ranking by percentage variation because it takes unit price and the scale of consumption into account.
3. PARAMETRIC BENCHMARKING: this is a method rather than a numerical indicator. It is an approach to comparing buildings, processes and even vehicles, in which the fixed and variable components of consumption are compared separately. Notably if you have a manufacturing process whose consumption has a straight-line relationship with one driving factor, the gradient of the line is a measure of process efficiency and can be compared with that achieved by comparable installations regardless of their scale. The intercepts may not lend themselves to comparison. On the other hand with delivery vehicles you can separately compare the gradients (which correspond to vehicle fuel economy) and intercepts (which might tell you about driver behaviour in terms of idling).
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11 MAY 2020

A LEARNING CURVE
The idea of there often being a straight-line relationship between consumption and some independently-measurable 'driving factor' is well-known and useful. However, people sometimes see curved relationships and want to know if they are likely to be valid. The answer is that it depends; but you should not assume a curved relationship without physical justification. I have encountered two circumstances where a curve was plausible. The first related to power feeding the motors of a paper-making machine. Here, by virtue of the process being continuous, output could really only be varied by changing the speed of the machine, and frictional losses in rotating machinery increase exponentially with speed. Each additional 1% increase in speed incurs higher additional losses, so that what might otherwise be a straight-line relationship curves upwards.
The other example occurs where you are trying to monitor gas consumption in a diverse campus of buildings. Each building on its own might have consumption linearly related to degree days but because each has different thermal characteristics, some will balance at lower outside air temperatures than others. As a result, the campus will pick up gas demand progressively as the weather gets colder (with some buildings holding off) and vice versa as it gets milder. The net effect will approximate to a curve.
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1 APRIL 2020 (APRIL FOOL'S DAY)
Some readers will remember the so-called 'signature meter' that was marketed ten or so years ago. This was a kWh meter which could reportedly discriminate between over 83 different connected electrical appliances being turned on and off. It did not take off at the time but thanks to the current transition from big data to immense data (ID) the concept has returned in the guise of 'software-defined electricity'.
With software-defined electricity your power supply waveform would be sampled more than 37 times a microsecond, processed in the cloud and dynamically corrected to remove spikes, holes and resonant ramps so that connected equipment uses less energy, runs cooler, and enjoys extended life. Phase-shifting arrays (similar to those used in multi-antenna 5G beam-forming transmitters) will allow a parallel-wired power conditioner to target individual loads on a customer's premises so that they operate as an internet-of-things (IoT), each at its own unique current and frequency, thereby running cooler and enjoying extended life.
With people increasingly working from home, it even allows their additional energy expenditure to be monitored and charged back to their employer. In effect, every connected device will act as its own microgrid with blockchain technology embedded in the optimisation algorithm to give near-real-time trading and market reconciliation up to the seventh harmonic, using less energy, running cooler and enjoying extended life. Exciting stuff and all thanks to the Immense-Data Internet of Things (IDIoT).
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30 MARCH 2020

HEAT PUMP ENERGY ESTIMATES
We are increasingly seeing heat pumps either in active use or under consideration for new projects. Your fellow reader Will S. wrote for some advice. He says if he were working out a kWh yearly duty for biomass, gas etc, he would use degree day data; however, for air-source heat pumps the coefficient of performance (CoP) improves with a rise in outside temperature. He wondered if there is process for dealing with this shift. So here goes...
The theoretical CoP is related to the evaporator and condenser temperatures (Tevap, Tcond) expressed as absolute temperatures:
CoP = Tevap / (Tcond - Tevap)
For example if Tcond is 52°C (325K) and Tevap is 2°C (275K):
CoP = 275 / ( 325 - 275 ) = 5.5
To get the real-world CoP it is common to multiply the theoretical number by 0.6 or something of that order. Also remember when considering heating, add 1.0 to give the system CoP.
The important point is that as well as the heating load itself increasing with falling outside temperature, so does the mechanical power required to supply each kWh of that heat. This turns what would otherwise be a straight-line relationship between energy and heating degree days into a curved one.
For Will's purposes, however, the solution would be to use a bin analysis:

Create a table of outside air temperature bands and the hours per year spent in each band;
add a column for the building kW heat loss for each band; and
add a column for the estimated system CoP
From these numbers one can calculate the annual kWh for each outside-air temperature band and thus the annual total.
Degree-day analysis will still have a role if one is looking at an existing heated building because the gradient of its energy-vs-degree-day line is denominated in kWh per degree day. If you divide that gradient by 24 you get kWh per degree hour, which is kW per degree inside/outside temperature difference (as required for step 2).
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25 FEBRUARY 2020

HUMIDITY
We commonly track heating and air-conditioning consumption by reference to outside air temperature (using degree-day statistics) but one of my readers has humidity control in his buildings and wondered whether there is an analogous method for tracking variation in demand induced by fluctuating outside-air moisture content.
This is indeed something I've done before and there is a write-up on my web site here.
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30 JANUARY 2020

FLEET ENERGY REVIEWS: COMPANY CAR CHOICES
A common recommendation in fleet energy reviews is to limit employees' choice of company car. One neat idea I picked up from Chris Endacott (who instructs our transport energy and carbon courses) is to not permit vehicles incurring more than a certain benefit-in-kind percentage. Such a policy naturally encourages climate- and budget-friendly choices and as future government policy tightens, so your fleet standards will improve without you needing to rewrite your rules.
Remember also when you cap BIK, the fuel cost savings are enhanced by savings in Employers' National Insurance contributions.
Related to this there is a simple spreadsheet that you can build for a car fleet of any size. Tabulate the business fuel consumption (actual or estimated) for each car, and work out what each would have consumed if the car had a certain benchmark emissions figure (I use a not-very challenging 150 gCO2/km, but inflate all manufacturers' gCO2/km ratings to real-life equivalents using the DBEIS uplift factors, e.g., 1.315 for 2017 ratings).
You can then work out the 'performance deficit' for every vehicle in the fleet, this being the energy (or money) that would be saved if no vehicle in the fleet exceeded the benchmark. I did a fleet of 20 cars this week, nine of which it turned out were costing Ł1,000 a year or more in excess of benchmark. These nine together account for over Ł22,000 of excess annual costs in fuel.
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20 JANUARY 2020

DEGRADED PERFORMANCE REPORTING
One of my clients operates a handful of Scania lorries fitted with telematics that allow him to view weekly and monthly statistics for each vehicle including, for example, kilometres driven. Unfortunately, although the telematics system also records fuel consumption, the reports do not show that data. Instead they display a calculated figure for kilometres per litre. This should allow us to back-calculate the fuel figure except that the km/l value, which is usually around 3 or 4, is only quoted to one decimal place of precision. So suppose for example that the vehicle does 4,838 km and achieves 3.4 km/l. Divide one by the other and you get 1,422.9 litres. The problem is that '3.4' could represent any value between 3.350 and 3.499, which means that the true answer could actually be, with equal probability, any value between 1,382.7 and 1,444.2 litres (+/- 2%). For the purposes of analysis I would far rather have the original fuel measurement and not this approximation.
Now it is quite true that the figure for km/l (as presented) could be tracked through time, and benchmarked against other vehicles. That is probably how Scania imagined the results would be used. But performance indicators expressed solely as a ratios like this are always second-best because they do not take the scale of consumption into account. The risk is that you end up focussing on a very poor performer that covers few miles when the real opportunity lies with a moderately bad performer doing high mileage. And if you want to study changes in behaviour you need figures for absolute actual consumption to compare with expected values, so that you can use cusum analysis and related techniques.
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2 DECEMBER 2019

GOING THE EXTRA MILE
Among the information supplied to me recently as part of a fleet energy review was the annual mileage for company car users, one of whom had claimed 40,000 business miles. If we assume that you can maintain at best an average of 40 miles per hour on most trips, she will have been spending around a thousand hours a year behind the wheel, or half of her contracted employment hours.
Leaving aside whether this is the best use of an employee's time, one should bear in mind that driving even only 30,000 miles a year carries risks equivalent to working on an offshore oil rig, compounded in this case by the temptation to fill the idle time with mobile phone calls. An employee in that position should certainly receive training in safe driving.
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25 NOVEMBER 2019

EXCEPTIONALLY ACCURATE?
When reporting exceptions as part of routine energy monitoring, accurate consumption data are obviously important. But we should not forget that we need accurate figures for driving factors as well, since these are the basis of calculating the expected consumption against which actual values are gauged. An error either side affects the results.
The most widely-used driving factor is degree days. According to the International Performance Measurement and Verification Protocol (IPMVP) degree-day figures from government sources can be regarded as error-free; but this is evidently unrealistic. Temperature readings that are just 0.1C too high would yield monthly values that are up to 3 degree days below the correct value. Even just the fact that degree-day figures are often rounded to whole numbers is an issue. Half a degree either side of a published value of 20, for instance, represents 2.5% error. But the major source of error in published degree-day figures is that they were measured somewhere else, not at the site being monitored. This is not fatal - far from it - but it needs to be taken into account.
Nor are production statistics immune. For instance they often involve counting discrete chunks of output. Chunks completed near the start of a day may have used energy the previous day so a few minutes either way can effectively misallocate that item. As an aside, the most extreme example I ever encountered was a factory where the workers routinely manipulated records to make it look like they had been working on Sunday when in fact they had not (as the daily monitoring of compressed-air use proved). Their management was up to similar tricks; they were in the habit of allocating the output of Week 1 every year to Week 52 of the previous year, so as to flatter the figures.
Falsifications aside, errors in both consumption and driving factors will reduce the accuracy of exception reports and anybody who uses a fixed percentage threshold for exceptions can expect to see more false alarms than necessary (as well as missing some real exceptions). The solution lies in how the threshold is set. The best way is to set individual control limits based on the uncertainties observed in each metered consumption. Those cases where there has consistently been wide variation between actual and expected consumption need to be given wider tolerance bands, while those where agreement has tended to be good can be allowed to trigger exceptions on relatively small deviations.
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11 NOVEMBER 2019

VOLTRAGE
Reader Richard G. was surprised to read an Observer article on the Guardian web site in which a network operator, Electricity North West (ENWL), was touting the benefits of voltage reduction as a way to cut customers' bills. The article correctly stated that customers' kettles would take longer to boil because of reduced power output, but suggested wrongly that their consumption would go down as a result. In fact, it will slightly increase because the longer heat-up time increases the duration of heat loss from the kettle, and that extra heat loss needs to be made up from extra electrical energy input (the amount of heat put into the water is the same, so no effect on consumption there). This same perverse result - higher consumption at lower voltage - will apply to all thermal appliances operated on intermittent cycles.
I looked at some research that ENWL had commissioned on parts of their network, which had shown that a 1% drop in substation voltage had resulted in a 1.3% drop in power to connected customers. That is plausible but not the whole story. It's true that for some unregulated appliances like incandescent lamps and toilet extract fans, reduced power will have resulted in reduced output (which nobody noticed) and hence lower energy consumption. But for thermostatically-controlled appliances like space heaters, ovens and immersion heaters, lower power will be compensated for by increased run times and there will be no saving. ENWL's public-relations people have confused power (kW) with energy (kWh).
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28 OCTOBER 2019

BLAME THE FLAME
An energy audit report that I reviewed for someone recently recommended replacing a heating boiler with a condensing model, and cited the low efficiency of the existing unit. As evidence, the report showed the combustion test result slip that you always get these days after a maintenance visit.
However, close examination of the test results showed that there might be a cheaper solution, because the stack temperature was 425°C. Reducing that to a more reasonable 250°C (say) would cut gas consumption by about 12%. The cause would need to be investigated, but cleaning the heat-exchange surfaces or derating the burner would be the typical solutions. Maybe both.
The burner must have been in a poor state. Reported excess air was 57% (which itself will add a couple of percent to fuel consumption) and yet carbon monoxide was 260 parts per million, indicating incomplete combustion. All in all, a strong case for sorting out the maintenance and maybe fitting a new (smaller) burner; not a whole new boiler.
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7 OCTOBER 2019

DOES MY BOILER LOOK BIG IN THIS?
Last week while reviewing an ESOS audit report for a building that was heated 24/7 I tried a sense check on annual gas consumption against installed boiler capacity and concluded that the heating system was running at an annual load factor of 15%, which struck me as rather low.
To establish whether the boilers were oversized I used the reported regression of gas consumed versus heating degree days. The author's analysis showed that sensitivity to weather was 92,000 kWh per month (equivalent to a fixed 3,016 kWh per day) plus 2,500 kWh per degree day. I assumed, conservatively, that the design coldest day is 5 degrees below zero. That equates to 20.5 degree days if the base temperature is 15.5C. Consumption on such a day would be 3,016 + (2,500 x 20.5) = 54,266 kWh. Spread over 24 hours that is equivalent to a demand of 2,261 kW measured at the gas meter; or at 80% efficiency, 2,261 x 0.8 = 1,808 kW boiler output.
Hence my conclusion was that the boilers, six of them with a combined 3,660 kW rating, had roughly double the required output capacity. Surplus boiler capacity causes energy waste through (a) excess standing losses and (b) the purge losses associated with unnecessarily frequent burner start-stop cycles. So one immediate opportunity was simply to isolate three of the six boilers; the other would be to ensure that boiler sequencing control is working properly.
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1 OCTOBER 2019

FAR INFRA-RED HERRING
I have decided that the phrase "far infrared" (FIR) will henceforth count as a trigger word for bogus energy-saving claims. First used in 1923, FIR is radiation with wavelengths between 10 and 1,000 microns, which (digging in physics books) corresponds to temperatures in the range 3 TO 290 degrees absolute. That's minus 270 to plus 17 Celsius.
So when regular reader Will S. drew my attention to an electric radiant heater that claimed to use FIR I was intrigued, and looking more widely on the web I found the term used in relation to saunas and therapeutic clothing, suggesting that it is one of these legitimate scientific terms that has been co-opted for the promotion of snake-oil products.
I have nothing against radiant heating in principle. Quite the contrary: for selective heating of spaces that are sparsely or intermittently occupied, or subject to high air throughput, it is likely to be more economical than warm air heating. But the case study that Will sent me was amusing. It concerned a hair salon whose gas-fired central heating system had been replaced with radiant panels. Fair enough, except that some of the panels took the form of heated mirrors. I don't know what the emissivity of a mirror is, but I'll wager it's closer to zero than one. The vendor may care to reflect on that.
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26 SEPTEMBER 2019

HEATING MATS
Thanks to readers Alan T. and Catherine C., among others, for sending me links to interesting advertising claims. Alan's referred to electric heating mats that can be embedded in the surfaces of walls, floors and ceilings. The product in question is low voltage, which was claimed (citing Ohm's Law) to be more efficient than mains. Of course it is neither more nor less energy efficient since all the electrical energy supplied to an electric heater emerges as heat regardless. It was also claimed to be safer. While it is true that a low-voltage shock would not be lethal, one has to bear in mind that the distribution wiring will be much more heavily loaded: at 24 volts a 1 kilowatt load draws over 40 amps.
PV WINDOWS?
Catherine's query was about a novel form of photovoltaic cell exploiting a physical principle called plasmonics (which a scientist friend tells me is a real thing). Plasmonic nanoparticles, we are told by the vendor's web site, "can absorb up to ten times as much light as other known materials". Not including lampblack I presume. It goes on to say that this yields a highly transparent cell, which at first seemed odd for something that absorbs light so well, but I think they meant they could print the cells onto window glass in some form of fine grid that allowed a lot of light through because they can harvest more electricity from what little they do intercept. I have heard of PV glazing before and it has always struck me as a peculiar idea: if you can tolerate the inevitable loss of light, why not just have smaller windows and put the PV element on an opaque part of the building?
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2 SEPTEMBER 2019

AN ILLUMINATING COMPARISON
Regular reader Clare C. was surprised when she checked the cost advantages of LEDs as replacements for metal halide (MH) high-bay fittings in a warehouse. She discovered that MH lamps have luminous efficacies very similar to LEDs. Both can yield about 100 lumens per watt, so it looked like she wasn't going to get the 50% saving she was after. She asked my opinion.
There are a couple of factors that would tip the balance in favour of LEDs. Firstly, she needs to account for the fact that unlike LEDs, MH lamps need control gear which would add some parasitic load (say 20 watts on a 400-watt lamp). Secondly, LEDs are inherently directional and can deliver all their output more effectively to the working space; MH lamps are omnidirectional and need reflectors which may waste some of the light output. So in terms of useful light output per circuit watt, a well-specified and correctly-installed LED fitting may have a moderate advantage.
But the big gain is in controllability. MH lamps have a warm-up time measured in minutes and a 'restrike' time (after turning off) which is longer still to allow them to cool before being turned on again. It does not matter how long the delay is; it inhibits the use of automatic control so MH lamps are often turned on well before they are needed, and then stay on for the duration. LEDs by contrast can be turned off at will and as soon as they are needed again, they come on. It is through automatic on/off control that Clare might get her 50% saving.
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27 AUGUST 2019

THERMAL STORAGE IN BUILDING FABRIC
Ice storage is sometimes used in central air conditioning systems as a way of smoothing demand for chilling, thereby reducing the installed chiller capacity or allowing demand to be time-shifted. It’s attractive because the latent heat absorbed or released as the water changes phase between liquid and solid is an order of magnitude more than can be stored and recovered just by heating or cooling liquid water.
Phase-change storage is a legitimate and effective element of central air conditioning and heating plant, but we now see vendors offering phase-change materials to be embedded in the fabric of buildings. They claim to stabilise internal temperatures and thus save energy. Are such claims likely to have any merit?
I suspect not, albeit with the exception of one specific set of circumstances. For my reasoning see EnManReg.org/pcm.
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1 AUGUST 2019

WHAT IS A TREE WORTH?
We all know that trees are good and absorb carbon dioxide. But how good are they? Let's work it out...
Trees absorb carbon dioxide at different rates depending upon their age, species and other factors but as a rough order of magnitude you can say the figure for a typical tree is 10 kg per year. meanwhile the carbon emissions associated with energy use are 0.2 kg per kWh for natural gas and (in the UK in 2018, including transmission losses) an average of 0.3 kg per kWh for electricity.
So 50.0 kWh of gas or about 33.3 kWh of electricity each generate the 10 kg of CO2 that a single tree can absorb in a year. Take that figure for electricity. As a year is 8760 hours, 33.3 kWh equates to a continuous load of only 3.8W. So one entire tree compensates for one broadband router, or an electric toothbrush, or a cordless phone, or a TV on standby (roughly).
And as for gas consumption: remember pilot lights? The little flame that burns continuously to ignite the main gas burner? If you had pilot flame with a rating of 100 watts, in the course of a year it would use 876 kWh and require no fewer than 17 trees to offset its CO2 emissions.
I like trees - don't get me wrong - by all means plant them for shade, wildlife habitat, fruit or aesthetic appearance. But when it comes to saving the planet I just think that given the choice between planting a tree and cutting my electricity demand by 3.8 watts I know what I would go for first.
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18 JULY 2019

MAGNETIC TECHNOLOGIES
Forget magnetic combustion enhancement -- this week someone tried to sell one of my readers "kinetic-based magnetic technology power generation...powered solely by magnetic technology" which, they claim, generates power with no fuel and zero pollution.
This is obvious nonsense but they use the old trick of seeding their literature with references to stuff that really exists, in this case magnetic torque amplifiers. We all use torque amplifiers every day; they are better known as gearboxes, and a magnetic torque amplifier couples the rotating elements magnetically rather than using mechanical teeth. I found a good article (link below) on magnetic couplings in general but there are two applications which deserve mention from an energy-saving standpoint.
The first, and simplest, is straight in-line 1:1 magnetic couplings. These are tolerant of slight misalignment and do not put radial load on the shaft bearings either side: this reduces mechanical transmission losses.
The second application is called an eddy-current clutch. This consists of a nested pair of concentric cylinders of magnetically-susceptible material. The outer cylinder is driven by the motor (running at constant speed) and the inner cylinder, which is mounted on the output shaft, is magnetised by a variable-voltage excitation coil. When magnetised, the inner cylinder tries to chase the outer cylinder; the stronger the field, the greater the torque transmitted. A tachometer on the output shaft regulates its speed via a control circuit driving the excitation coil. If the driven load is a fan or pump, it will obey the affinity laws whereby the power absorbed varies with the cube of the speed. At low fan speed the motor, even though itself running at full speed, only has to develop low torque, and therefore it absorbs less electrical power. So you get the energy benefits of variable speed without some of the complications. For example the motor would not need an auxiliary cooling fan for slow running, and without an inverter in circuit there are no harmonics to cause power-quality problems.
The article on magnetic couplings is at www.engineerlive.com

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15 JULY 2019

HYDROGEN IN AN ESOS ASSESSMENT
Reader Dave G. wanted to know whether he should include, in an ESOS assessment, hydrogen used in a bronze furnace. The furnace is electric but hydrogen is used to react out the oxygen from the air inside it, so as to create a non-oxidising atmosphere. My view is that it would be prudent to include it in the reference-period total, since its combustion must contribute to the thermal input. In all likelihood the energy input from hydrogen will be so small that it can be treated as a 'de minimis' use which need not be audited; however, as a lead auditor I would expect to see the figures to justify that.
What about SECR? Hydrogen is unusual as a fuel gas because it generates no carbon dioxide. However, its use will still need to be reported under SECR. Under Regulation 20D(3)(a) of the Companies (Directors’ Report) and Limited Liability Partnerships (Energy and Carbon Report) Regulations 2018, hydrogen counts as gas, whose combustion yields energy that must be reported in kWh terms. Oddly oil, whose combustion definitely does generate CO2, is exempt from reporting under those Regulations.
THE ENERGY-CONSCIOUS ORGANISATION
A small group of us have been thinking about behaviour change not in the normal sense (something which organisations promote on the shop floor) but in a more holistic sense, bringing in the design and procurement of assets, for example, or addressing maintenance policies. It amounts to organisational culture change drawing in management and professional functions. I think an "Energy Conscious Organisation" could be characterised as follows. It minimises its use of fuel and electricity by…

Engaging and involving everyone at all levels and in all functions;
Encouraging vigilance, facilitating resolution of problems and exploiting opportunities;
Developing individuals’ skills and knowledge as needed;
Adapting its policies and processes to guarantee continual improvement;
Measuring, monitoring and reporting the results
For brevity we could reduce this to five watchwords: Vigilance—Engagement—Skills—Monitoring—Adaptation. If only that had a memorable acronym.
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11 JUNE 2019

PRIORITISING OPPORTUNITIES
You have to be a bit careful using performance indicators to prioritise energy-saving opportunities. Take this example of two trucks. Truck A covers 50,000 miles a year, returning 4 MPG against a yardstick value of 5 MPG, while truck B, which should give 4 MPG covers 14,000 miles a year at 2.5 MPG, which makes it look like the worse performer. It uses 60% more fuel than it should, while Truck A, at only 25% over, does less badly. Or so it seems. The issue is that Truck A does so many more miles: annually it will waste 2,500 gallons against only 1,800 for Truck B, and is therefore more deserving of remedial action.
Similar arguments can be made in respect of energy ratings for buildings. It isn't their percentage variance that is important: it is how much excess energy that variance accounts for, given the size of the building. The generic term that I use is PERFORMANCE DEFICIT. This is the quantity of energy consumed in excess of yardstick expectations in a given
The performance deficit approach even works in situations where a simple ratio-style performance indicator is inappropriate: you can use it when expected consumption contains an element of fixed consumption, and where there are two or more factors driving variation.
WHEN IS AN EXCEPTION SIGNIFICANT?
Many people (including, unfortunately, some purveyors of monitoring and targeting software) treat as "exceptions" any variation from expected consumption greater than a certain fixed percentage. This is an unnecessarily crude method which will tend to yield false alarms and miss some worthwhile opportunities.
A better method is to set individual margins of error for each thing you monitor: wide margins for those things that are erratic and hard to model, and tight for those that are more predictable. For those with a statistical turn of mind, plus or minus two standard deviations is a serviceable control limit because only one observation in 20 is likely to go outside that band just by chance. Tuning the control limit in this manner enables some smaller but avoidable deviations to be detected, which suppressing alerts when bigger deviations occur on things that are inherently less predictable in the way they behave.
I give away a free monitoring and targeting toolkit which will enable you to try this with your own data: contact me if you want a copy.
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2 JULY 2019

LIGHT ENTERTAINMENT
One of my clients alerted me recently to a new product that looked suspicious: a lamp technology styling itself "Laser Crystal Ceramic" whose promoters claim various advantages over LED lamps. I couldn't find any references to such a technology in English, as all the online material originates in Switzerland and is in German, French, and the type of machine-translated English that you get if you go via Klingon.
One can just make out the back story about a freak incident with a laser cutting machine "creating an inexplicable bright light..."; "Swiss businesses and universities unable to find the explanation..."; "breakthrough by a South Korean institute..."; "discovery that coating an LED element with a ceramic containing carbon compounds eliminated the need for cooling gases (?) in the lamp..."; you get the picture.
The online catalogue illustrates a huge range of lamp types. They sell just about every format you can get as conventional LEDs, in fact, which is not bad for something that came to market this year and only in Switzerland. The literature says that it is based on LED technology, but my guess is that it actually is LED technology. Certainly the claimed lumens-per-watt figures are similar, although a little on the high side. I tried to buy one of their lamps to take a peek inside but the shopping-cart feature on their mail-order site didn't work.
The serious point is that it will not be long before we start seeing "better-than-LED" lamps touted by English-speaking scammers. Buyer beware ("bISolnISbe'taHmeH yIyep woQ" in Klingon).
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27 JUNE 2019

NORMALISING BUILDING ENERGY CONSUMPTION
On Tuesday's monitoring and targeting course at the Energy Institute, we discussed 'normalisation' of building energy consumption, the process whereby you adjust for the effect of weather differences between them. Classically the adjustment is done for heating fuel only, using the ratio of regional annual heating degree days to the standard UK figure of 2,463 (base 15.5C). By extension a similar approach could be used for electricity when there is significant cooling load for air conditioning. For normalisation purposes the standard number of cooling degree days is 1,878 (to the default general-purpose base temperature of 5C).
One of the trainees asked if it would be possible to normalise consumption for a building which used electricity for both heating and cooling. The answer is Yes, but only if you can determine the sensitivites to heating and cooling degree days with reasonable certainty. In other words are you able to determine the constants c, k1, and k2 in the formula for monthly expected consumption E:
E = c + k1 x HDD + k2 x CDD
...where HDD and CDD are monthly heating and cooling degree days respectively. If so the following formula directly yields the normalised annual consumption E":
E" = 12 x c + 2,463 x k1 + 1,878 x k2
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10 JUNE 2019

CARBON IMPACT OF EMAILS
Reader Richard has seen a claim that an email accounts for 4g of CO2 emissions. He thought this might be an exaggeration, and I think he's right.
We can estimate the embedded energy of internet traffic from the marginal cost of data that carriers charge us. For example EE have two mobile phone plans for the Galaxy S10+ with unlimited calls but different data allowances. The 1 GB plan is Ł50 per month and the 60 GB plan is Ł59; so, from the difference, the marginal cost of data is Ł9 for 59 GB or Ł0.153 per GB. Assume (pessimistically) that half the cost of handling the data is energy, and that electricity costs the system operators Ł0.10 per kWh: then you have 0.153 x 0.5 / 0.1 = 0.763 kWh per GB.
The carbon intensity of that electricity is unknowable because the data bounces all over the world but if we use a UK-like figure of 0.6 kg/kWh that puts the emissions at 0.763 x 0.6 = 0.458 kg per GB.
The email from which this article came was about 25 kB so its associated emissions would seem to work out at 11 milligrams, many orders of magnitude less than the figure Richard had seen.
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28 MAY 2019

EXPLOITING COMBUSTION TESTS
These days there is no excuse for not knowing the combustion efficiencies of individual heating boilers. Even if you don't test them yourself, you should be getting a percentage figure after every service. This information is really valuable because a diligent contractor should at the very least make sure that every appliance is meeting its manufacturer's stated efficiency.
But it goes beyond that: wherever you have two or more boilers on a range, one may be more efficient than the others, and simply by making that one the lead boiler in the sequence you will save fuel at no cost. Furthermore, you could track the reported efficiency of each individual unit through time. That enables you to challenge the quality of maintenance when a test result is worse than previously reported, and to ratchet up your expectations when a test result is better than you've had before.
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24 APRIL 2019

DOMESTIC HOT WATER
In principle, domestic hot water (DHW) should not be a major energy cost. In a building where it is mainly used for hand-washing you can assume typically 4 litres per person per day, which works out at well under Ł10 per person per year even using electric heating - hence the popularity of point-of-use heaters. However, where central storage is used there will be standing heat losses, notably in the distribution pipework. Apart from the cost implications, DHW pipework has now been implicated as a cause of overheating in highly-insulated and airtight buildings.
Adverse behaviour (leaving hot water running to drain, or using hot where cold would do) will add to costs as well but the strangest story I heard concerned some people painting the inside of a hospital cold water header tank. After they had isolated and emptied the tank, it began to refill via its outlet. It transpired that hot water was entering the cold water system via mixer taps with defective non-return valves. This problem was completely hidden during normal operation when draw-off of cold water was sufficient to prevent the leaking hot water from filling the tank past the overflow.
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1 APRIL 2019 (APRIL FOOL'S DAY)

ENERGY AFTER BREXIT
Thinking about the laws that are likely to change post-EU, the most significant from an energy standpoint are the laws of science, meaning it is likely that:

fuels will become susceptible to magnetism, enabling even more complete combustion than can be obtained through proper maintenance;
the internal metallic layers in multi-foil insulation will be able to reflect heat back through the adjoining insulant and out through the surface foil;
heating-water additives will enable radiators to heat up quicker but release heat more slowly;
boiler anti-cycling devices that cut fuel consumption during periods of low load will do the same under medium and high load conditions which account for the majority of annual fuel consumption;
insulating paints will be as effective as conventional insulation materials that are 4,000 times thicker;
temperature sensors in freezers will respond more accurately and rapidly when encased in a cube of gel;
putting solar panels in refrigeration circuits will enable even more heat to be pumped out with the same electrical input;
'kinetic' pavements will generate enough energy to power a display showing how many steps passing people have taken; and
voltage-reduction devices will enable electrical equipment to perform the same work with lower energy input, and will themselves no longer incur standing power losses.
These insights are provided courtesy of Laboratoires Farage.
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18 MARCH 2019

ENERGY IN KITCHENS
A while ago I went to survey a restaurant which had exhibited very poor performance in a benchmarking comparison. One clear opportunity concerned its high ceilings: warm air was pooling at high level, at a temperature over 35C, while diners were sitting in uncomfortably low temperatures because cold air was being drawn through the restaurant by the kitchen extract system. Destratification fans, and a balancing fresh air supply for the kitchen, were the recommendations.
Demand for ventilation air in catering establishments in general is likely to be very peaky, meaning that there will often be scope for improved time controls, or even dynamic controls which sense the demand for fresh air. Heat recovery from the extract air could also be possible. It would be complicated by the need for filtration, and in all likelihood one would need to pipe the heat to other parts of the building since kitchens themselves are probably the last places that need the extra heat: "run-around coils" are the technology that achieves that.
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11 MARCH 2019

OPTIMUM START CONTROL
"Optimum start" control (OSC) is an alternative to fixed time control on heating systems. Implemented either as stand-alone device or as an algorithm in a building energy management system, OSC delays heating-system startup until the latest possible time consistent with having the building reach the required temperature at the right time. By eliminating unnecessary preheat, it shaves a bit off your fuel consumption.
Unfortunately there are various ways that this can go wrong and end up wasting fuel. Here's how. An OSC monitors the internal space temperature overnight in order to gauge how long a preheat period will be needed in the morning. The next day it checks whether the target temperature was achieved at the target time, and if necessary adjusts its assumptions about the achievable warm-up rate. It should therefore, progressively get better and better at judging the best startup time.
But...
Various things can interfere with this process. For example, setting the daytime set-point below the target temperature. Result: target temperature is never reached, so the OSC adds extra preheat time. The same will happen if the internal sensor is in an unheated space, or if the boilers are disabled through the summer without the OSC having been set to holiday mode. The result will be a needlessly extended preheat period -- I have seen it exceed 24 hours, which is why OSCs now often have, dare I say it, a backstop.
Another common mistake is to set the OSC start time as if it were a fixed timeswitch. Result: the OSC strives to have the building up to temperature by 05:00 or whatever.
Automatic controls are the key to fuel economy and can be among the most cost-effective of retrofit measures. But they need to be properly commissioned. If you have them already, put them top of the list for auditing, and then use monitoring and targeting to continually assess their effect.
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25 JANUARY 2019

WHEN FLOOR AREAS CHANGE
Reader Jean-Marc wrote with a question about how to compute percentage savings when consumption is affected by the weather, production throughput and floor areas. The bit about floor areas raises interesting issues.
First of all, although varying floor areas would cause variation in consumption, they do not routinely vary and it is therefore all but impossible to use the normal statistical tricks to determine how changes will affect consumption. He will need to fall back on engineering adjustments. He can expect changes in floor area to have a proportionate effect on sensitivity to degree-day values, some impact on fixed consumption, but probably no impact on sensitivity to product throughput.
But there is another, less obvious point. He will need to discriminate between (a) changes imposed by business need, like extensions to accommodate additional work, and (b) discretionary reductions undertaken deliberately to improve resource efficiency while keeping an unchanged portfolio of activities.
In case (a) it is appropriate to build the effect of the change into your expected-consumption model. This is because the change is externally imposed and local managers have no control over it. It is like the weather or the size of the order book in that respect and it would be wrong for example to ignore the disposal of a building and take credit for the reduced energy consumption that results. However, the same is not true of case (b). Here, typically, we are consolidating existing activities into smaller premises, and it is correct to take credit for the resulting energy saving, which we can only do if we leave our expected-consumption formula unchanged.
In general when choosing factors to incorporate in an expected-consumption model, anything over which managers have NO control is a candidate. Conversely the factors over which they DO have control should be excluded.
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21 JANUARY 2019

A NEW ANGLE ON BENCHMARKING BUILDINGS
When comparing the energy performance of buildings with each other, you normally use a year's worth of consumption. But what if you don't have a whole year's history, for example because the building has been altered or changed its use? The answer, as long as you have some monthly or weekly consumptions spanning a range of weather conditions, is to build a degree-day regression model and use its parameters to extrapolate to a full year.
Extrapolation is straightforward. Suppose the building exhibits a response to heating degree days such that its expected energy consumption E on a monthly basis is given by
E = k0 + k1.HDD
where HDD are monthly degree-day values. Then annual consumption A will be:
A = 12.k0 + k1.SHDD
where SHDD is the standard annual degree days to the chosen base temperature.
Using the standard annual degree day figure (see table) saves a separate normalisation step. And even if you do have a whole year's consumption data, this method can still be advantageous because it enables you to strip out unrepresentative periods caused by exceptional circumstances.
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17 JANUARY 2019

DRIVING FACTORS FOR FIXED OR IRREGULAR CONSUMPTIONS
When analysing patterns of energy use, our usual starting point is a straight-line relationship between consumption and a relevant driving factor. The choice of driving factor might be simple (degree-day figures for heating and air conditioning, product throughput in energy-intensive processes and so on) although sometimes it needs to be a bit more complicated.
However, another question often arises, namely what to do if consumption isn't actually expected to vary from week to week. Although the default answer is just to use the average weekly value as the expected consumption, there's a trick I recommend, which is to use heating degree days. This might sound odd because the scatter diagram that you get should just be a random pattern, with a best-fit line that is horizontal since the weather presumably explains none of the observed variation.
Why do I do it? Because sometimes the consumption does turn out be weather-related after all when you didn't expect it. Some years ago when analysing general electricity use at a university campus I discovered a correlation which implied that 41% of consumption was unaccountably weather-related (unaccountably, but not inexplicably of course). And yesterday while benchmarking some retail units I found a circuit labelled 'UPS' -- uninterruptible power supply -- which during the summer had the expected near-zero consumption, but which increased in winter, varying with heating degree days to a 10C base. Somebody's got a heater plugged into a secure outlet. UPS? Oops.
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19 DECEMBER 2018

IMAGINARY SAVINGS
I suppose most readers will have heard of 'power factor' (for those unfamiliar with the concept, I cover it as one of my kitchen table-top talks at https://youtu.be/Slmk91cWZuw ). Poor power factor is a Bad Thing because it increases the current that must be drawn in order to deliver the same amount of real power to, say, an electric motor.
Poor power factor is associated with high 'reactive power' and among the supposed energy-saving products that I have been asked to review recently is one that claims to capture that reactive power and somehow feed it back into the customer's equipment. The problem? Reactive power is just a mathematical construct and -- rather like the square root of minus one -- it is imaginary, so good luck trying to capture it.
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5 NOVEMBER 2018

CATEGORISATION FACTORS
If you are responsible for energy management in a large portfolio of buildings, you might want to classify them into groups that have significant features in common. That helps make benchmarking more meaningful, and for any given energy-saving intervention will help establish the scope for replication.
One trick for identifying the features that buildings share is a brainstorming technique called 'repertory analysis'. Pick three buildings at a time at random, and for each of them pose this question: in what respects does it differ from the other two? For example in a supermarket chain you might get answers like 'has a petrol station', 'does not have a bakery', 'is located in a covered mall', and so on. After repeating the process a few times you'll have a list of possible factors which you can winnow down.
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15 OCTOBER 2018

COOL RECEPTION
Reader Donald F. writes that he is being pestered by someone selling an additive for chilled water circuits which supposedly gave a 16% reduction in an office's energy requirements for air conditioning, although to be fair they only claim 5-15% for the normal run of business. But is even 5% plausible?
We can get a feel for this with a rough calculation and some simplifying assumptions. Firstly we're talking about indirect cooling systems, whereby the refrigeration plant cools water which circulates in a closed loop through water-to-air heat exchanger coils. The first thing we can say is that the air temperature off the coils is fixed: let's pick a value of, say, 10°C. To keep it simple suppose we say that we need chilled water at an average of 5°C to achieve that and that we have an approach temperature of 1° in the chiller's evaporator. This gives us an evaporation temperature of 4°C.
What would happen if heat transfer could be improved in the coils and evaporator? It would reduce the total temperature differential between evaporation (currently 4°C) and off-coil air which is fixed at 10°C. Of the four heat exchange surfaces, we are affecting only two, and to be generous let's suppose we can improve their heat transfer coefficients by 20% (actually I am not sure that's even feasible, but bear with me). That 20% improvement on half the heat transfer surfaces gives us a 10% improvement overall, so the 6° differential would drop by 0.6° and evaporator temperature would thus rise from 4.0 to 4.6°C.
Now the theoretical coefficient of performance (CoP) of the chiller is given by TE/(TC-TE) where TC and TE are the condenser and evaporator absolute temperatures. TE we have said starts at 277.0K (4°C) but might increase to 277.6K. Say TC is 323K (50°C). So the pre-dosing theoretical CoP is 277.0/(323.0-277.0) = 6.022 while the post-dosing figure is 277.6/(323.0-277.6) = 6.115. This is an improvement of only about 1.5% in overall system efficiency. One can quibble over my assumptions but it looks like the plausible limit of savings is at least an order of magnitude lower than claimed even if (and it is a big "if") an additive of any kind could really improve heat transfer.
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22 AUGUST 2018

THE DRIVE TO IMPROVE EFFICIENCY
Reader Graham B. asked about losses in belt drives, as he is contemplating switching to direct-coupled motors. This is possible thanks to the ability of variable-speed drives (VSD) to run fan motors at low speed.
Drive efficiencies are given on page 19 of Carbon Trust Guide CTV048 but in essence V, cogged, wedged, toothed and flat belts have different inherent efficiencies which also vary with time and depend on how they are installed and maintained. There are trade-offs with higher-efficiency types: flat belts need to be well-tensioned, which increases bearing loads, while toothed belts need much less tension but run with a whirring noise which may be a nuisance. In all cases the energy saving from eliminating belts is accompanied by improved reliability and lower maintenance costs, not least because VSDs start the equipment gently.
Contrary to what some might think, virtually no energy saving arises from the fact that the directly-coupled motor runs slower. The motor must provide whatever mechanical power is demanded by the fan, which all other things being equal will stay the same. Apart from a small reduction in speed-related motor losses, the electrical input power will therefore not change. Slowing the fan, on the other hand, does yield savings and that raises another option: changing the pulley sizes. For example changing the ratio from 1:4 to 1:5 will drop the air throughput by 20% but nearly halve the fan's mechanical power requirement, with consequent electrical savings approaching 50%. It is the driven equipment's speed, not the motor's, which determines the load.
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15 AUGUST 2018

WHAT CONSTITUTES A "SIGNIFICANT ENERGY USE"?
Reader Paul R. wanted guidance on what should be treated as an SEU, given that things like lighting and HVAC account for different proportions of the energy consumed in different industries.
In the definition of an SEU used by ISO 50001 an energy use is significant if it accounts for 'substantial energy consumption' or offers 'considerable potential for energy performance improvement'. You can turn this into a consistent methodology as follows. Suppose you have various energy uses consuming, in absolute terms, x1, x2, x3, .... xn kWh per annum. In each case (and this is admittedly subjective) you can assign a fraction (0-1) representing the proportion of consumption that could reasonably be saved with modifications, or avoided with better management. Call these fractions y1, y2, y3, .... yn. Simply evaluate x1.y1, x2.y2, etc., and you will have a list of the deemed savings opportunities in kWh. Convert these to cash equivalents and rank in descending order and there you have it: a list of energy uses in order of significance.
You don't need to be wildly accurate. You just want to get things in more or less the right order with a reasonable order of magnitude attached to each. You can then pick as few or as many as you wish from the top of the list.
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17 JULY 2018

AIR CON?
One of my clients asks me to help vet sales proposals for energy-saving products. We recently looked at a retrofit air-conditioning controller which claimed to save 25% to 40%. Is this plausible?
Well, just as you can save heating fuel by not overheating a space, so you can save electricity by not overcooling it. On the heating side readers are probably familiar with the rule of thumb that reducing average indoor temperature by one degree C will cut 8-10% off your fuel consumption. I looked at prevailing conditions in the Birmingham area for the sake of an example, and concluded that if cooling is needed all year round because you have a low balance point (say 5 deg C), then a one-degree elevation would shave just 14% off your cooling energy. But if cooling is provided only seasonally and your balance point is say 16 deg C, the same one-degree elevation could yield a 36% saving.
A building balancing at 16 deg C in Birmingham will have a cooling season running from March to October. It is this short cooling season which boosts the percentage saving towards the levels claimed by the advertiser I was evaluating. With the longer cooling season of a hotter climate, the plausible percentage saving is lower. And of course you are relying on being able to raise the average internal temperature by one degree without perceived loss of service; which may or may not be possible.
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11 JULY 2018

'STANDARD' DEGREE DAYS
Reader K.M. has asked how the table of standard monthly heating and cooling degree days on my web site was derived, and like many others before him wonders whether in fact regional average degree-day values should be used for normalising fuel consumption.
To take the second question first, a regional average is absolutely the wrong figure to use as a normalisation reference (a) because it prevents inter-regional comparisons and (b) because any trend for the weather to become warmer will flatter the results: you will be calculating what the consumption would be under progressively milder weather. For normalisation against published benchmarks, or against similar buildings elsewhere whose annual consumption may have been measured at other times, all consumptions must be adjusted to the SAME, UNVARYING reference weather. In the UK for 40 years or more the standard weather year has been taken as 2,463 heating degree days to a base of 15.5C. Nobody knows where that number came from, and it does not matter, because any arbitrary value would have served the purpose.
The table of standard monthly heating and cooling degree days (www.vesma.com/ddd/std-year.htm) is based on that figure of 2,463 but is extended to cover heating and cooling degree days to assorted base temperatures, including monthly as well as annual values. The numbers were calculated for consistency with the 2,463 figure using a synthetic weather year derived from Birmingham whose climate is representative of non-coastal England.
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9 JULY 2018

A TRAP FOR THE UNWARY
The half-hourly electricity meters used for billing large supplies have an unfortunate design feature which often leads to them being misread.
It's like this. As well as maintaining a register containing the total kWh consumed to date, the meter keeps separate track of the subtotals in defined tariff bands (day, night, evening and weekend, winter afternoon, etc). The meter is interrogated electronically but also displays a kWh total which can be read manually. Unfortunately it does not show the grand total: it shows the subtotal for the active charge band. Read the meter on a Monday morning and you'll be recording the 'day' total kWh; on a Saturday you'll be reading 'evening and weekend' totals. I first realised this some 20 years ago when I noticed that a meter reader appeared to have started reading a different meter each week. He hadn't: it was the same meter but he had changed when he read it, and none of the readings he had ever sent had been the total kWh that we wanted. My associate Daniel has just found the same with one of our M&T clients. Reader Bob W. has meters which display the date by default and that's what he sometimes gets as a reading.
I wrote a few weeks ago more generally with advice about manual meter readings, and stressed the need for briefing your meter readers. In this case they need to be shown (a) the button to press to index through the available registers and (b) at the very least, which of the registers is the grand total.
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25 JUNE 2018

VERIFYING SAVINGS FROM FABRIC IMPROVEMENTS
When you set up a baseline model for consumption of heating fuel, you should use degree-day figures calculated to a base temperature equal to the 'balance point' of the building, that is, the temperature below which artificial heating becomes necessary.
If you improve the insulation of the building, it will lower the building's balance point. Will this invalidate the baseline model? Fortunately not. The baseline model exists to estimate what consumption would have been in the absence of the energy conservation measure so it is appropriate to keep the original model unchanged. Of course a degree-day model can also be used to extrapolate annual consumption under standard weather conditions. The post-retrofit model should use degree-day figures based on the new reduced base temperature. You can download annual totals from www.vesma.com/downloads/hdd_regional_totals.pdf.
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11 JUNE 2018

ON AGAIN, OFF AGAIN
On-off testing is a method that can be used for verifying energy savings in cases where the energy-saving measure can be bypassed or disabled at will. Generally speaking, where it can be used it is advantageous because in principle it averages out the effect of any unmeasurable influences on consumption. Furthermore, by looking at the 'on' and 'off' observations as separate sets it is possible to quantify the background randomness, which enables you to tell if your observed savings are significant. You could for example set a threshold of two standard deviations as proof that the observed savings were not just down to chance.
The method is not always safe, however. There is a particular problem with voltage reduction, where although you might perhaps see an apparent saving in energy consumption at low voltage, the associated reduction in output would not be evident. In certain cases the deficit in output during low-voltage intervals would then be made up during high-voltage intervals, exaggerating the apparent (stress: apparent) difference between the 'on' and 'off' conditions. Moreover, if the voltage reduction device remains energised when idle, on-off testing will fail to pick up the continuous extra background load which it imposes on your supply.
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22 MAY 2018

MAGNETS
Someone on my A-Z course last week asked for advice on how to resist the advances of a magnet salesman. I sent her the usual material: a half-page relatively non-technical refutation, and the report of independent testing done by John Crabb at Exeter University in 1997. I also advised her to seek an explanation as to why the product does not appear on the Energy Technology List maintained in support of the Enhanced Capital Allowances scheme (a tax break for installing energy-saving equipment).
It occurred to me that one could also pitch one supplier against another so I have been digging in the archive for claims made by different suppliers. Let's start with Magnatech. Their web site makes a bald assertion that passing fuel through a magnet’s negative and positive (?) fields makes it easier for the fuel to bond with oxygen and burn. They offer no explanation of how this works but say it creates a rise in flame temperature of "an extra 120°C or more". Maximus Green say that the flame temperature only rises by 20°C, but they gamely have a crack at explaining how: they claim that hydrocarbon fuel molecules clump together in large "associations" because they are randomly charged positive and negative (although if that were true, wouldn't they just pair up?). Passing through a magnetic field, they say, gives all the molecules a positive charge, breaking up these supposed big clusters of fuel molecules. They don't say where all the resulting spare electrons go.
Maxsys, meanwhile, are having none of this lumpy-gas stuff. Their 2014 brochure lays the blame on very fine dust in the fuel. By applying a magnetic field, they say "nanoparticles that would normally pass through the combustion or reduce heat transfer efficiency, by clinging to and fouling surfaces, begin to cluster together", an effect which forms "larger colloids, less likely to create a film deposit and compromise a plant's performance". Now pardon my scientific knowledge, but a "colloid" is a stable suspension of very fine particles in a liquid. Milk is a good example. Be that as it may, Maxsys are saying that magnetic fields cause things to clump together, in direct contradiction to what we heard earlier from Maximus Green. Someone is telling porkies and I will leave it to you, dear reader, to work out who.
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10 MAY 2018

IT'S COOL
Among the "is it snake oil?" enquiries that I get from readers, there are always some relating to air-cooling systems that don't use chillers. In fact this is perfectly feasible and is called adiabatic cooling. I first encountered it on a subway platform where they had fans fitted with water-mist sprays and it works like this. When the air is at low relative humidity and you spray water into it, the water evaporates readily. However, the phase change from liquid to vapour (which is what happens, albeit the liquid water is in microscopic droplets) requires heat, and that heat comes from the surrounding air. As a result, having lost some of its heat content, the air's temperature falls and the result is air at a lower dry-bulb temperature and higher relative humidity. You can try this at home, as it were, by keeping a water spray bottle in your car: it will precool the interior quickly if you've parked in the sun.
Of course in most situations we don't want the extra moisture in the air, so commercial adiabatic cooling systems are usually indirect, working via an air-to-air heat exchanger or precooling the air feeding air-conditioning condensers.
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19 APRIL 2018

MANUAL METER READINGS
Despite the explosion in the use of automatic meter reading, many readers may well still have meters that are being read manually. If you do, here are a few pointers that will help you get organised:
1) Decide on a frequency (daily, weekly or whatever) and a preferred time for readings. Stress to meter readers that they should record the actual date and time at which they read each meter, otherwise they may simply put down the time at which they were supposed to do it (not the same thing);
2) Assign responsibility to a named individual for each meter-reading round, obviously, but nominate a stand-in to cover for holidays and illness;
3) Either provide printed meter-reading forms or handheld terminals;
4) Decide a policy on whether or not to record decimal digits. I would say yes, because it is all information;
5) Provide training because not everyone is a natural meter-reader;
6) Ensure access, which may mean anything from having keys or security clearances to making sure that the managing director is not parking over the water meter manlid;
7) Label the meter positions, so that someone unfamiliar with the task will find it less perplexing; and
8) Create a meter schedule. This should state the meter position, what commodity it is measuring, what units it records in and what it feeds. I would include at least one definitive reading taken by someone who knows what they are doing. Photographs of meters are also helpful.
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9 APRIL 2018

PANTS ON FIRE AWARD
And the winner is... DB2 Management OÜ who sell a product called 'Ecovolt'. This device, which plugs into a standard 13A wall socket, is claimed to cut 30-50% off your electricity consumption. What makes it a stand-out candidate for the Pants on Fire Award is the advertisers' invocation of conspiracy theory. To quote their web site: "for obvious reasons, this product has been kept secret by power companies looking to continue their profiteering tirade".
Their web site includes a short video purporting to prove the device's energy-saving effect. It shows a pair of electric hair clippers on an extension adaptor drawing 0.28 A. When the Ecovolt device is plugged into a neighbouring socket, the current falls to 0.08 A. Electrical engineers will recognise this as an example of power-factor correction and nothing to do with reducing the real power drawn by the appliance; like the EPS Energy Saver which I reported on a couple of years ago, the Ecovolt probably contains a big capacitor and not much else.
The visitor to the web site sees continual pop-up notices saying that Tatiana, Sara, or Phillip and so on have just ordered Ecovolt. Keep your eye on those alerts for more than 70 seconds and Tatiana, Sara and Phillip appear again followed by six other repeated names. That's the kind of loyal customer we all want.
The firm operates out of a Post Office Box in Tallinn, Estonia. Thanks to Paul Harding for bringing this absurdity to my attention.
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1 APRIL 2018 (APRIL FOOL'S DAY)

UNIVERSAL ENERGY-SAVING SOLUTION
I bring you news of the first ever universal energy-saving product. It is a multi-award-winning patented gel, discovered by an ex-NASA scientist, which boasts a unique combination of nano-magnetic and photo-piezo-electric properties.
Used as an additive in heating-system water it has a triple action. Firstly by reducing surface tension, it improves thermal contact between the water and internal heat transfer surfaces. As a result radiators heat up faster and cool down more slowly, saving energy. Secondly it removes air (improving thermal contact between the water and internal heat transfer surfaces). Removing air means less corrosion and scaling, while its nano-magnetic properties repel any residual magnetite. As a result radiators heat up faster and cool down more slowly, saving energy. Finally it fills in the gaps between water molecules, improving thermal contact between the water and internal heat transfer surfaces. As a result radiators heat up faster and cool down more slowly, saving energy.
The product can also be applied to radiators externally as a paint which promotes heat transfer through far infra-red radiation. As a result rooms heat up faster and cool down more slowly, saving energy.
Another way to use it is as a wall paint. Used externally, its embedded nano-scale vacuum bubbles allow it to act as a superinsulator: just 0.25mm thickness is the equivalent of 7cm thick conventional cavity fill or exterior wall insulation. As an internal paint applied to the wall behind a heating radiator it reflects wasted heat back into the room, which then heats up faster and cools down more slowly, saving energy. The gel changes to a solid at exactly your preferred room temperature, absorbing or releasing latent heat. As a result of this ‘phase change’ action, when applied as an undercoat for interior wall paint or as a wallpaper adhesive, the room will heat up faster and cool down more slowly while maintaining a steady temperature, saving energy.
It can even be used for painting windows, where its photo-electric properties allow it to generate free energy from the sun without loss of light transmission into the room, and as a floor paint its piezo-electric properties mean it can capture energy from passing pedestrians, generating enough power.
It has benefits in plant rooms and substations, too. As a coating on gas or oil supply pipes, its nano-magnetic effect yields all the benefits of the different types of awkward and bulky bolt-on magnetic devices. For example by rearranging the ortho- and para-hydrogen molecules it promotes more complete and rapid combustion. It also aligns the fuel molecules and makes them more reactive, which promotes more complete and rapid combustion. In the case of oil fuels this calorific value enhancement (CVE) can be further increased by adding the product to the fuel itself, where it alters a previously-undiscovered property of the oil to make its molecules more reactive, which promotes more complete and rapid combustion.
The gel is non-Newtonian, so its action does not have any equal and opposite reaction, making it an ideal lubricant to reduce energy losses in gearboxes.
On electrical systems the product can be applied to the outer insulation of supply cables where its nano-magnetic properties will optimise the voltage without the need for transformers or other lossy electrical devices. Moreover, it has the effect of counteracting the random ‘Brownian motion’ of the free electrons in the conductors so that they move in a more orderly manner through your electrical equipment, improving its efficiency by up to several percent.
As a refrigerant additive, it modifies a previously-unknown property of the refrigerant fluid, causing it to absorb heat faster and release it more slowly, saving energy, and when applied to the thermostat sensor of a freezer it shields it from the effects of changing temperature, reducing the operation of the refrigeration compressor and saving energy.
Prove you're green: buy Trumputine.
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26 MARCH 2018

F IS FOR... FREEZERS
The job of a food freezer is to maintain the stored product in its entirety at or below a stipulated temperature, usually -18C. In a walk-in freezer this is achieved by thermostatically controlling the condenser fans which chill the air within the freezer.
Somewhat disturbingly, products are on sale which are designed to slug the response of the freezer temperature sensor so that it "does not respond to rapid air temperature fluctuations when the doors are opened". Hmmm... I would prefer something to happen about it immediately when warm air gets in, otherwise the surface layers of stored product will spend time above the permitted temperature, with attendant risk of spoilage.
Even with the doors closed, slugging the thermostatic response will increase the duration of each on-off cycle. The reduced frequency of compressor starts is represented by the vendors as evidence of energy saving. Nonsense: all other things being equal, the same amount of heat will have flowed into the freezer, so the same amount of chilling will be required to remove it. Compressor runs may be less frequent, but they will be longer. But the main thing is that degraded thermostatic response increases the magnitude of temperature swings (allowing higher maximum temperatures) and whatever the vendors may say about the benefits of mimicking the core temperature of the product, the outer layers need to be kept below the stipulated temperature just as much.
Thanks to reader Nick P. for the question which prompted this article.
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18 MARCH 2018

AIR (REMOVAL) WARFARE
Reader Russell S. contacted me about a sales pitch for a product called Oxypod, which claims to remove air from heating systems and thereby directly and indirectly improve their thermal efficiency. Air separators are pretty much standard equipment on heating systems. Typically they provide a chamber in which the system water moves relatively slowly in contact with a medium presenting lots of sharp edges on which microbubbles of entrained air can nucleate and coalesce before floating off and being discharged through an air release valve. The Oxypod by contrast accelerates the flow, creating a vortex which is claimed to promote the discharge of what they call 'dissolved' air.
A search on the Advertising Standards Authority web site brought up the following story. In 2014 Goodwin Community Trading, who sell the Oxypod, complained (ASA ref. A14-275319) that a company called Sold On Renewables was making claims for a competing device called the Vortex Energy Saver, based on testimonials and tests carried out when the Vortex was being sold as the 'Tadpole'. The ASA rejected their complaint on the grounds that a mere change of product branding did not in itself invalidate any claims for it. It's worth noting that Goodwin could hardly attack the actual claims being made for the Vortex/Tadpole, since they were making similar claims themselves, and moreover the competing products are based on the same principle.
Then the tables were turned: Tadpole complained to the ASA about Goodwin's Oxypod. The upshot was that the ASA ruled in 2016 that Goodwin should cease making claims for 'up to 30%' energy savings, or indeed any claim that significant savings could be achieved, because they could not provide substantiation (ASA complaint A15-30540).
Ignoring the vendors' pseudo-scientific sales pitches and going back to first principles, it is implausible to claim savings of the order of more than a few percent from improved heat transfer. The argument for air removal is the same as for snake-oil water additives: any improvement in heat transfer will be manifested as a drop in boiler exhaust temperature, and a gas boiler capable of saving 30% would need to start with a chimney temperature around 600C (dull red heat).
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12 MARCH 2018

COMMON WEAKNESSES IN MONITORING AND TARGETING SOFTWARE
One of my great frustrations when teaching people about energy monitoring and targeting is that there are few M&T software packages that are good enough to merit a recommendation. In a recent article on the Energy Management Register blog I picked five particular weaknesses that seem to be pretty much universal:

Cusum analysis used solely for passive reporting, and not as a diagnostic aid;
Dumb exception criteria: often just a blanket threshold expressed in percentage terms;
Consumption assessed by comparison with the corresponding period a year before, or the immediate preceding period, or some other feeble reference;
Insistence on displaying all collected data with no attempt to filter according to significance; and
Superfluous decoration and gimmicky displays (great for the salesman but an assault on, and an insult to, the regular user).
There is a little more detail at www.enmanreg.org/weaknesses/
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7 FEBRUARY 2018

LOSSES IN GEAR AND BELT DRIVES
Reduction gearing is common where the driven equipment needs to run at a fraction of the speed of the electric motor which powers it (commonly just under 1500 or 3000 RPM when the supply frequency is 50 Hz). Belt drives can achieve the same, but both belts and gears incur mechanical energy losses and require maintenance.
In some circumstances it is possible to re-engineer things with the driven equipment (a ventilation fan, for example) directly coupled to its motor, with the motor run at low speed by means of a variable-speed supply set to a low frequency. As well as avoiding the transmission energy loss, this dramatically reduces maintenance requirements and increases reliability. Sign up for future bulletins | Energy management training | Ask a question

5 FEBRUARY 2018

ENERGY MONITORING FOR OBJECTS THAT SWITCH BETWEEN MODES
“Brigadoon” was a 1940s Broadway musical about a mythical Highland village that appears in the real world for only one day a year (although as far as its inhabitants are concerned time is continuous) and its plot concerns two tourists who happen upon this remote spot on the day that the village is there. The story came to mind some years ago when I was struggling to deal with energy monitoring of student residences whose weekly fuel consumption naturally dropped during vacations... Or should have done. I realised I would need two different expected-consumption formulae, one for occupied weeks and another for unoccupied weeks, the latter using degree-days computed to a lower base temperature. In each case, therefore, I split the data history into two: one for term weeks, and the other for vacation weeks. Each history thus had very long gaps in it, but there is no objection to closing up the gaps so that in effect the last week of each term is immediately followed by the first week of the next and likewise for vacations. For the purposes of cusum and other time-series analyses, the data must be sequential (in the right order) but not necessarily consecutive.
This strategy made the single building into two different ones. Somewhat like Brigadoon, the ‘vacant’ manifestation of the building for instance only comes into existence outside term time, but it appears to have a continuous history.
A similar approach can be used in various industrial monitoring scenarios. For a fuller article please see www.enmanreg.org/brigadoon/ or get in touch if you'd like advice on a specific application.
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29 JANUARY 2018

DOOR AIR CURTAINS
In situations where it is necessary to keep a building's outer doors open, you will sometimes find "air curtains", fans which blow a sheet of air down across the width of the doorway. These are an effective way of preventing dust, fumes and insects getting in through the door: they are entrained in the outer layer of airflow, and where the jet hits the floor it splits, with the outer layer discharging the contaminants back outside.
Some suppliers of air curtains claim that they conserve energy as well. The basis of this claim lies in what would naturally happen in an open doorway in still conditions, namely convective circulation in which warm air at high level flows out to be balanced by cold air flowing inwards at low level. This effect will be especially marked with high doorways. The claim for air curtains is that they disrupt the flow of escaping warm air, forcing it down to floor level where the jet splits, with the warm inner layer returning inside.
However, even in still conditions there is a problem here, because the fan is drawing air from high level inside and at floor level only half of it returns inside. 50% of the internal air drawn into the fan is diverted outside when the jet splits at floor level. A further problem with pedestrian doorways particularly is that the air curtain usually needs heating to prevent the perception of cold that the air's velocity would create. If the building actually doesn't need that heat, it is all a waste of money. Even if it does need heat, half is still wasted because it ends up outside.
In windy conditions the argument for air curtains as heat barriers really breaks down. A moving sheet of air is simply not as effective as a door. If there is any differential pressure whatever, that sheet of air will be displaced, and the problem is exacerbated if there are open doors or windows on the far side of space - or extract fans. In one memorable instance I visited a restaurant that operated an open-door policy. Their air curtain had a 20kW heater that ran continuously, but the downjet did not reach the floor: at about 60cm it turned inwards along with a layer of cold air at floor level, thanks to the kitchen extract depressurising the space.
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11 JANUARY 2018

E IS FOR... ENERGY PERFORMANCE COEFFICIENT
Most kinds of energy performance indicator are not up to the task. In industry, the most widely-used metric, kWh per unit of output, is all but useless because its value is naturally variable, increasing at low outputs and vice versa because of the effect of fixed overhead consumption. These changes mask the truth: poor performance at high output can perversely appear better than efficient operation at low output. Meanwhile people are no better off in the world of data centres, where the prevailing convention is to use 'power utilisation effectiveness' defined as the ratio between total electricity consumption and power delivered to the I.T. equipment housed in the centre. This metric varies at the mercy of the weather, misleadingly making performance look worse on hot days.
Furthermore, if you operate a process whose energy consumption is influenced by more than one driving factor, you are completely stuck as there is no single thing to divide consumption by.
The answer is to compare actual consumption with what you'd expect it to be under prevailing conditions. Just as, for routine exception reporting, you should evaluate and cost the DIFFERENCE between actual and expected consumption, to construct a robust and stable performance indicator you take the RATIO of actual to expected consumption to give what we call the 'Energy Performance Coefficient' (EnPC). EnPCs can be applied in any context, are inherently unaffected by variations in factors like throughput and weather, easily cope with consumptions affected by multiple drivers, and can even be numerically scaled to mimic the useless traditional performance indicators that they replace.
For a fuller explanation of EnPCs you can download a more detailed paper here: vesma.com/downloads/enpc-rev01.pdf.
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7 JANUARY 2018

G IS FOR... GEARBOX
Reduction gearing is common where the driven equipment needs to run at a fraction of the speed of the electric motor which powers it (commonly just under 1500 or 3000 RPM when the supply frequency is 50 Hz). Belt drives can achieve the same but both belts and gears incur mechanical energy losses and require maintenance.
In some circumstances it is possible to re-engineer things with the driven equipment (a ventilation fan, for example) directly coupled to its motor, with the motor run at low speed by means of a variable-speed supply set to a low frequency. As well as avoiding the transmission energy loss, this dramatically reduces maintenance requirements and increases reliability.
Indeed for fan applications up to about 12kW, the conventional induction motor may beneficially be substituted by an electronically-commutated motor which itself has inherently better energy efficiency.
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5 JANUARY 2018

ENERGY MONITORING FOR OBJECTS THAT SWITCH BETWEEN MODES
“Brigadoon” was a 1940s Broadway musical about a mythical Highland village that appears in the real world for only one day a year (although as far as its inhabitants are concerned time is continuous). Its plot concerns two tourists who happen upon this remote spot on the day that the village is there. The story came to mind some years ago when I was struggling to deal with energy monitoring of student residences whose weekly fuel consumption naturally dropped during vacations... Or should have done. I realised I would need two different expected-consumption formulae, one for occupied weeks and another for unoccupied weeks, the latter using degree-days computed to a lower base temperature. In each case, therefore, I split the data history into two: one for term weeks, and the other for vacation weeks. Each history thus had very long gaps in it, but there is no objection to closing up the gaps so that in effect the last week of each term is immediately followed by the first week of the next and likewise for vacations. For the purposes of cusum and other time-series analyses, the data must be sequential (in the right order) but not necessarily consecutive.
This strategy made the single building into two different ones. Somewhat like Brigadoon, the ‘vacant’ manifestation of the building for instance only comes into existence outside term time, but it appears to have a continuous history.
A similar approach can be used in various industrial monitoring scenarios. For a fuller article please see EnManReg.org/brigadoon or get in touch if you'd like advice on a specific application.
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29 JANUARY 2018

DOOR AIR CURTAINS
In situations where it is necessary to keep a building's outer doors open, you will sometimes find "air curtains", fans which blow a sheet of air down across the width of the doorway. These are an effective way of preventing dust and insects getting in through the door: they are entrained in the outer layer of airflow, and where the jet hits the floor it splits, with the outer layer discharging the contaminants back outside.
Some suppliers of air curtains claim that they conserve energy as well. The basis of this claim lies in what would naturally happen in an open doorway in still conditions, namely convective circulation in which warm air at high level flows out to be balanced by cold air flowing inwards at low level. This effect will be especially marked with high doorways. The claim for air curtains is that they disrupt the flow of escaping warm air, forcing it down to floor level where the jet splits, with the warm inner layer returning inside.
However, even in still conditions there is a problem here, because the fan is drawing air from high level inside and at floor level only half of it returns inside. 50% of the internal air drawn into the fan is diverted outside when the jet splits at floor level. A further problem with pedestrian doorways particularly is that the air curtain usually needs heating to prevent the perception of cold that the air's velocity would create. If the building actually doesn't need that heat, it is all a waste of money. Even if it does need heat, half is still wasted because it ends up outside.
In windy conditions the argument for air curtains as heat barriers really breaks down. A moving sheet of air is simply not as effective as a door. If there is any differential pressure whatever, that sheet of air will be displaced, and the problem is exacerbated if there are open doors or windows on the far side of space - or extract fans. In one memorable instance I visited a restaurant that operated an open-door policy. Their air curtain had a 20kW heater that ran continuously, but the downjet did not reach the floor: at about 60cm it turned inwards along with a layer of cold air at floor level, thanks to the kitchen extract depressurising the space.
Postscript: follow-up from readers included one who said that air curtains can work as a barrier against excess humidity in hot climates, a claim that was borne out by another who said they worked well keeping hydrocarbon fumes out of the shops on filling-station forecourts.
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11 JANUARY 2018

E IS FOR... ENERGY PERFORMANCE COEFFICIENT
Most kinds of energy performance indicator are not up to the task. In industry, the most widely-used metric, kWh per unit of output, is all but useless because its value is naturally variable, increasing at low outputs and vice versa because of the effect of fixed overhead consumption. These changes mask the truth: poor performance at high output can perversely appear better than efficient operation at low output. Meanwhile people are no better off in the world of data centres, where the prevailing convention is to use 'power utilisation effectiveness' defined as the ratio between total electricity consumption and power delivered to the I.T. equipment housed in the centre. This metric varies at the mercy of the weather, misleadingly making performance look worse on hot days.
Furthermore, if you operate a process whose energy consumption is influenced by more than one driving factor, you are completely stuck as there is no single thing to divide consumption by.
The answer is to compare actual consumption with what you'd expect it to be under prevailing conditions. Just as, for routine exception reporting, you should evaluate and cost the DIFFERENCE between actual and expected consumption, to construct a robust and stable performance indicator you take the RATIO of actual to expected consumption to give what we call the 'Energy Performance Coefficient' (EnPC). EnPCs can be applied in any context, are inherently unaffected by variations in factors like throughput and weather, easily cope with consumptions affected by multiple drivers, and can even be numerically scaled to mimic the useless traditional performance indicators that they replace.
For a fuller explanation of EnPCs you can download a more detailed paper here: vesma.com/downloads/enpc-rev01.pdf
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8 JANUARY 2018

FLAVOURS OF DEGREE-DAY DATA
Prompted by a recent enquiry about 20-year average degree-day figures, it might be useful just to review what these averages are for and how they relate to 'current' and 'standard' values.
Let's start with the 'current' figures. These are values published on a weekly or monthly basis, region by region, and they reflect the actual weather. Their purpose is to provide an index against which your actual fuel consumption can be compared as part of ongoing routine monitoring. For example in the Midlands the heating degree-day value (base 15.5C) was 21.7 in the week to 6 October 2017. Successive values can be added together to give annual totals; these are one of the ingedients required if you are trying to normalise your annual consumption. For example in the Midlands the total heating degree days (base 15.5C) for the year to September 2017 was 1,939.
For normalisation purposes you also need a figure for the 'standard' weather year. There is a single standard number of heating degree days for any given base temperature (likewise for cooling). To enable correct normalisation between regions and from one year to the next, these 'standard' degree days are fixed values that do not vary by region. For example the standard number of heating degree days (to base 15.5C) has always been 2,463 for anywhere in the country.
Lastly when we want an indication of expected future weather for a given month in a particular region we typically take the average of the last 20 corresponding results. For example taking the Midlands, the average degree-day value (base 15.5C) over the last 20 Januaries was 334. Twenty-year average values really have no other use than forecasting demand. They vary from one region to another but change only slowly, so they are typically only updated once a year and the new set supercedes the old.
Here are some useful links:

For standard figures: vesma.com/ddd/std-year.htm
For 20-year averages: vesma.com/downloads/uk_20year.xls
For ongoing reports contact info@degreedaysdirect.com

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6 DECEMBER 2017

BITCOIN'S ENVIRONMENTAL FOOTPRINT
Amid the headline hype about the meteoric rise in the "value" of bitcoins it is easy to miss a significant energy story. The process of "mining" the coins consumes a vast amount of computing power... Not least because huge numbers of miners are continually doing the same intensive processing simultaneously, even though the output from only one of them will actually be used by the system. As a result, the annual consumption of electricity associated with bitcoin mining and transactions already matches that of Morocco and every bitcoin transaction now uses over 250 kWh. There is a load of fascinating reading on this topic at the Digiconomist web site.
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20 NOVEMBER 2017

KINETIC PLATES
A piece appeared in "Energy World" this month about the Berlin Festival of Light, where a 'kinetic pavement' has been installed supposedly to harness energy from passing pedestrians. An article along similar lines appeared two years ago on the website of the Institution of Mechanical Engineers. This helpfully showed a display screen connected to such a system installed in Brighton, stating that 54,267 steps had generated 217,028 watt-seconds. I hope all my readers can confirm for themselves that this equates to a mere 0.06 kWh.
In 2009 Sainsbury's installed a kinetic plate at their Gloucester store to take energy from customers' cars as they approached the car park. An article in the Guardian claimed that it could generate "30 kWh per hour". Yeah, right... I calculate it would take traffic of the order of eight hundred thousand cars an hour to do that -- assuming 100% conversion efficiency (see www.enmanreg.org/kinetic-plates)
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6 NOVEMBER 2017

THERMAL ENERGY STORAGE WITH PHASE-CHANGE MATERIALS
Thermal energy storage can be beneficial for a variety of reasons. In air conditioning for instance, by levelling cooling demand it can reduce the capacity of chillers that one needs to install. Moreover, chillers run at night will not only tend to be more energy-efficient because of the colder ambient air, but electricity prices will be lower.
Ice storage is one of the techniques used in these circumstances because freezing water stores a lot of cooling energy relative to just changing its temperature: the heat removed in chilling 80 kg of liquid water by one degree would match the amount absorbed by making just one kilogram of ice. This latent heat effect can be achieved at other temperatures by substituting other materials for water. The process is generically known as 'phase-change' energy storage.
Naturally, like many genuine techniques, phase-change energy storage crops up in dubious offerings as well. I recently heard of a decorative wall covering containing a phase-change material with a melting point of around 22C, which its vendors claim would stabilise room temperatures and thus somehow save energy. Would in-room thermal storage be likely to save energy? Here are four scenarios:
• Scenario 1: the room temperature varies, but does not cross the product’s melting point. Here there will be no effect.
• Scenario 2: the control system maintains the room temperature continuously at or near the product’s melting point. Again, no effect.
• Scenario 3: cold weather, intermittent occupancy: say the room starts unoccupied with temperature below product melting point. Room occupant arrives and activates heating with set point above product melting point. Temperature rise is interrupted while product melts; this (a) delays the time at which set point is achieved and (b) stores heat which is later released (for no purpose) after the room is vacated and heating turned off. Result will be increased fuel consumption and possible occupant dissatisfaction.
• Scenario 4: hot weather, intermittent occupancy: suppose room starts unoccupied with temperature below product melting point. Heat gains cause temperature rise: just past the product melting point, it absorbs heat, so internal temperature is held steady for a while and peak room temperature is thus achieved somewhat later. Room occupant later arrives and activates cooling with a set point below product melting point. As temperature passes product melting point, product dumps (unwanted) stored heat into the space, delaying time at which set point is achieved. Result: possible customer dissatisfaction but no energy saving because the product never actually prevented heat getting into the space in the first place, so it still needs to be pumped out.
The vendors have taken a known technique, phase-change energy storage, and 'co-opted' its reputation. They also liken the effect to 'increased thermal mass'. This is sneaky. Many readers will have heard of thermal mass in buildings, and to hear it cited as one of the benefits of a product subtly fools us into assuming that it is an advantageous feature (why else would they mention it?). In fact, of course, slower thermal response will in some circumstances be the wrong thing to go for.
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30 OCTOBER 2017

D IS FOR ... DETUNING
This is a postscript to last week's item about power factor correction (PFC) capacitors. Stephen Barker, one of the speakers at next month's MAVCON17 conference, wrote that it is highly recommended to use 'detuned' PFC these days because electronic equipment, which is becoming prevalent, generates harmonic distortion - high-frequency components superimposed on the 50 Hz AC supply. Harmonic currents head directly for the low impedance offered by the capacitor and as a result standard PFC capacitors often fail very quickly indeed. Adding a correctly designed detuning reactor solves the problem. Detuned PFC is about twice the cost of standard PFC so isn’t heavily promoted - but subject to the careful evaluation of the practicalities and commercial viability, can still be a worthwhile investment.
My friend Kris Szajdzicki of ND Metering meanwhile drew my attention to another possible adverse effect of poor power factor: voltage drop. He wrote that this is known to have a serious impact on variable-frequency drives (particularly older ones) and to increase the effect of harmonics. Another argument in favour of power-factor correction.
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27 OCTOBER 2017

C IS FOR ... CORRECTION CAPACITOR
"Poor power factor" is the phenomenon whereby alternating current and voltage get out of step, leading to less real power being delivered than is implied by just multiplying volts by amps. Or, more realistically, leading to higher-than-necessary current being needed to generate the same real power.
This doesn't waste much energy as such (although line and transformer losses will be higher) but it does lead to higher transmission and distribution charges and will limit the maximum power you can draw from your supply. The solution is to fit capacitors, passive components that counteract the effect of things like electric motors that make the alternating current lag behind the voltage. I've posted a video on Youtube that illustrates both the problem and the solution with a mechanical analogue: https://www.youtube.com/watch?v=Slmk91cWZuw
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24 OCTOBER 2017

B IS FOR ... BASELINE
In common parlance, an energy 'baseline' is a reference value against which future consumption is gauged in order to assess changes in performance. Typically, baselines refer to a chosen 12-month period and are either 'absolute' (meaning the total quantity of energy used) or 'relative', that is to say expressed in terms of a metric such as kWh per unit of manufacturing output. Neither approach is particularly satisfactory in practice.
For a better way to look at it, start with the observation that consumption per week (or other interval) is partly constant and partly proportional to one or more independently-measurable driving factors such as production output, total duration of darkness, or the weather reckoned as degree days. This means you can derive a formula for expected consumption. Now the constants in that formula will have had certain values during the baseline period. That baseline FORMULA is rather useful because if we put into it the values of driving factors measured over some later interval, the result is an adjusted reference value against which to gauge actual consumption during that interval, with the effects of the variable driving factors automatically taken into account. As well as evaluating performance over a single week we can do it for a year or any other time-span.
Importantly, a baseline formula can be derived from data collected over any time-span. We are not compelled to use a year (even for weather-dependent loads) and known unrepresentative observations can be omitted if necessary. This is altogether a better approach. The paradigm shift? Treat 'baseline' as an adjective, not a noun.
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16 OCTOBER 2017

A IS FOR ... AUTOMATIC CONTROL
Automatic control should be high on the list when you are looking for opportunities to save energy; either introducing it where it did not exist before, or recommissioning and tuning it where it suffers from incorrect settings or has fallen into disrepair.
Building energy management systems are a clear candidate. Not only do they yield savings by regulating fuel and electricity use: they also help you to spot anomalous conditions in your plant (thereby avoiding energy waste through maintenance interventions) and their ability to record conditions through time provides invaluable diagnostic support. On lighting systems, auto control not only saves energy but gives the incidental benefit of creating an environment in which it is evident that the organisation cares about energy waste. In industrial contexts sensors can be used to start and stop conveyors, local extract ventilation, and other discrete items of equipment that do not need to run continuously.
Of course, the more you are saving through automatic control the more potential there will be for waste to occur when they go wrong, so routine monitoring and effective maintenance are critical.
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9 OCTOBER 2017

MONITORING ELECTRIC VEHICLES
Electric cars and vans are becoming a feature of many company fleets and with the advent of clean air zones and vehicles with a 200-mile range it is a trend that is only going to increase. Organisations that have so far not monitored electricity consumption for battery charging are going to have to think about it and Chris Endacott, the instructor on our transport energy assessment courses, recommends getting systems in place sooner rather than later, and not just for the obvious reporting reasons. Last week we were discussing a scenario where an EV user could charge up at work and flog the electricity to their supplier at home if they had the right smart-meter tariff.
Chris tells me that DEFRA's GHG reporting guidelines now include factors for both battery electric vehicles and plug-in hybrid electric vehicles (can also be used for range extended electric vehicles). But these factors are only needed when actual energy use data is not available so now is the time to make sure charging of electric vehicles, whether on-site or at-home, is being metered. If you don’t meter it then then you won’t be able to calculate energy efficiency (km/kWh) or cost savings, much less detect pilferage.
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21 SEPTEMBER 2017

ENERGY-SAVING OPPORTUNITIES
Anyone thinking about ESOS compliance will be faced with the need to commission or carry out energy audits or surveys. There are three generic approaches: checklist-based, product-led, and opportunity-led. The checklist-based approach suits simple repetitive surveys being done by less-experienced auditors; product-led surveys have a narrow focus on a particular technology, and typically apply where the energy manager has particular experience or a vendor has proposed a plausible solution (in which case one can leverage their expertise). Opportunity-led audits are those carried out by experienced auditors often with prior analysis of consumption patterns or after preliminary survey. These need wide expertise.
As for the categories of opportunity that will be found, these will be technical, behavioural, or procedural (i.e. to do with how the organisation manages energy). In the domain of technical opportunities the spectrum runs from things that are easy and inexpensive to those that are costly and disruptive. At the easy end we have, typically, opportunities to improve (or introduce) automatic control. Then we have the reduction of avoidable losses; then the pursuit of better component efficiencies (motors and drives for instance). Then, in manufacturing processes, we move on to the hard stuff: process layouts, process integration, and ultimately substitution of new alternative processes. One equivalent in the built environment might be better space planning leading to the closure of redundant buildings.
Opportunities arising under the 'behavioral' or human-factors heading would include: good housekeeping; overhauling maintenance practices; training; and improving vigilance and reporting. Finally under procedural opportunities we might find improvement of operating instructions, better scheduling, effective monitoring and exception handling and finally design feedback.
Going back to technical opportunities I have a tip. The most revealing question to ask, when looking at anything that consumes energy, is this: "How is that [insert name of object or process] controlled?"
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12 SEPTEMBER 2017

TOO GOOD TO BE TRUE?
A reader from Nottingham sent me an advertisement for an automotive bolt-on gadget which injects hydrogen into the vehicle engine's air supply and is claimed to reduce emissions of particulates and nitrogen oxides (NOx) as well as giving dramatic improvements in fuel economy - up to 33% in one case cited in their July 2017 brochure.
If true, the improvement in emissions is a neat trick to have pulled off because generally there is a trade-off: higher combustion temperatures, which tend to reduce particulates, also unfortunately favour the production of NOx. I cannot comment on that, as the independent test house that they refer to has so far not responded to calls or emails. But what about fuel economy benefits? As with many such impressive claims, it pays to turn the argument on its head: getting 33% more miles per gallon after the intervention implies that 33% of your fuel energy was previously being wasted. But where was that lost 33% going? The intervention only addresses the completeness of combustion. So was the energy being lost in soot or carbon monoxide? If so, the engine would be belching black smoke and fail its MOT. Was 33% of your fuel pouring unburnt from the exhaust? I hardly think so.
What about the fact that the injected hydrogen is itself a fuel? The device produces hydrogen by electrolysis. The only energy you can get back from the hydrogen is what went in during electrolysis to dissociate it from oxygen, but the 18 to 48 watts of electrical power reportedly drawn by the device must call for additional fuel input several times that figure because of conversion losses through the engine and alternator. So the generation and subsequent combustion of hydrogen will have a negative impact on fuel economy, albeit very small.
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4 SEPTEMBER 2017

ENERGY MANAGEMENT SYSTEMS CERTIFICATION - UPDATE
This concerns anyone currently certified to ISO50001 or thinking about doing it (for example as an ESOS compliance route).
ISO50001 is being revised, and the draft issued for consultation last week says, in a new clause 10.2, "The organization shall continually improve its energy performance". No such explicit requirement exists in the current version although thanks to ISO50003, which regulates their work in this area, accredited certifying bodies are not allowed to recertify an organisation that cannot demonstrate continual improvement. In fact thanks to ISO50003 new users cannot even get certified in the first place if they cannot prove performance has already improved.
However it is imposed, I think this new ‘hard compliance’ regime may have unintended consequences:
(a) High achievers could eventually reach the point where further marginal savings are uneconomic to pursue, effectively locking them out of recertification;
(b) As the potential for improvement tails off through time, the savings achieved become comparable to the margin for error. This effect, which the draft Standard fails to account for, makes it a lottery;
(c) Organisations that fail to gain recertification may well reduce their energy management efforts;
(d) At best, rational players have an incentive to postpone planned projects so as to ‘bank’ savings for later recertification cycles;
(e) At worst there is an incentive for users to use creative analyses to conjure savings out of thin air. This temptation is exacerbated by the moral hazard affecting auditors and certifying bodies that don’t want to lose clients;
(f) New users, and in particular those just starting to take energy management seriously, will be put off adopting ISO50001.
As any energy manager knows, just maintaining the savings you have previously achieved can be a hard trick to pull off and should in itself be recognised as a result. The original compliance regime was better in that respect because it allowed a measure of leeway in assessments.
ISO50001 was a good idea and it has worked well for many organisations, so I hope we will not see its user base eroded too dramatically. Meanwhile, given the new hard requirement, it will be critical how users set their baselines and evaluate their performance. That is definitely something I can help with.
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7 AUGUST 2017

ON-OFF TESTING
Most verification of energy savings is done by a before-and-after comparison but, as last week's discussion on boiler anti-cycling controls reminded me, some types of energy-saving device can be temporarily bypassed or disabled at will. For these it may be possible to do interleaved on-off tests. The idea is that by separately averaging the ‘on’ and ‘off’ consumptions you can get a fair estimate of the effect of having the device enabled, with any distorting external influences averaged out.
There are two pitfalls, and the one which can be exploited for boiler anti-cycling controls is to do the test during a period of low load (when significant savings may well be apparent) and then extrapolate the results as if they would be achieved at normal or high loads, which is very unlikely.
The other pitfall occurs when, with the device enabled, reduced energy input results in reduced output which then has to be made up in the following interval when the device is disabled. This will notably tend to happen with voltage reduction in electric heating applications. During a low-voltage interval the heaters will run at lower power; the resulting deficit in heat output would then need to be made up during the subsequent high-voltage interval, making it look worse than the low-voltage one. To minimise this distortion, be sure to set the interval length several times longer than the typical equipment cycle time.
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23 JULY 2017

BOILER ANTI-CYCLING CONTROLS
Scrabotnik (not his real name) asked my opinion of an email he'd received from someone selling bolt-on boiler 'optimisation' controls. These claim to reduce fuel consumption by altering the boiler firing pattern. Such devices are viewed with skepticism by heating control specialists (and indeed by each other's vendors) and they do make some pretty dubious claims, like savings of the order of 20%. They are also promoted with the pseudo-science and name-dropping that are the hallmarks of dodgy products.
As I have no concrete information on which to base a judgment, all I can do is answer in principle. My argument goes like this: in order to be able to save 20% without affecting the heating service, you must in the first place be using 25% more fuel than you strictly need, and using it in a manner that is avoidable. Assuming firstly that time and temperature control of the conditioned space are reasonably effective, that avoidable excess consumption must be occurring in the boiler room. But what aspect of operation is adding an avoidable 25% to your total year-round fuel consumption? If your boiler sequencing control is working, it cannot be standing loss from idle boilers. The only plausible culprit is ignition purge losses and indeed this is consistent with what the vendors say they are doing because ignition purge losses occur with each start-stop cycle and are a consequence of blowing ambient air through the combustion chamber briefly before and after firing. Increasing the length of the firing cycle to reduce the number of startups will reduce this loss. But are we really expected to believe that purge losses add 25% to your fuel consumption in their totality, let alone that proportion of them that you could avoid?
The implausibility of that idea can be seen by invoking Newton's Law of Cooling which says that heat flow between and object and its surroundings is proportional to temperature difference. When the boiler is firing, the temperature differential driving heat into the boiler water is hundreds of degrees; during fresh-air purging it will be a mere 60 or so. So on a conservative estimate a minute of purging will require no more than say ten seconds of firing to compensate. Now suppose your boiler is running at 50% load (30 minutes in each hour) and cycling on and off every 5 minutes with 2 minutes of purging each time. 12 starts an hour will call for 24 minutes of purging and as a result by my estimate 4 minutes of firing to make up the loss; that means we actually need to fire 34 minutes an hour rather than 30. Optimistically halving the number of starts would obviate 2 minutes of extra firing time, saving a mere 6%.
I am tempted to suggest that the household-name organisations that have been buying these things could profitably have sent their energy managers on one of my training courses ("Energy efficiency A to Z", or Certified Energy Manager). But then I would say that, wouldn't I?
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17 JULY 2017

MONITORING ENERGY IN DATA CENTRES
Reader Adrian wanted to know if cusum analysis can be applied to energy used in data centres. In fact it can always be used if you have a valid way of modeling expected consumption based on prevailing conditions and I had two suggestions from my own experience.
Firstly take an uninterruptible power supply (UPS) installation. With metering both sides you can treat output energy as the driving factor for input energy. You would expect a classic straight-line relationship with a finite intercept (no-load loss) and a gradient just below 1.0 (conversion efficiency). UPSs can then be benchmarked against each other in terms of intercept and gradient separately, and for any individual case you could also detect unexpected excess consumption - for example the deployment of excessive UPS capacity, which will show up as an increase in no-load loss.
Secondly for cooling plant you will classically see dependence on two driving factors: cooling degree days and ‘rack power’. I have seen one user with duplicated computer-room air conditioning systems detect a monthly change in performance as they switched between one system and another on the first of the month (although to do that you need to be monitoring on a daily basis).
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27 JUNE 2017

SMART PHONES AS ENERGY AUDIT AIDS
How many ways can your mobile phone help with energy surveys and audits? (1) as a camera, obviously; (2) as a stopwatch: for example timing a 1-bar drop in air pressure when you turn off your compressors, to estimate leakage; (3) as a means of reading inaccessible rating plates or meter dials; (4) to co-ordinate 'drop tests' where one person does spot meter readings while another turns major loads on and off; (5) as a hand-held meter-reading terminal using a web service like MeterPad; (6) just as a browser to gather information on unfamiliar plant and equipment.
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12 JUNE 2017

DUAL-PERSONALITY PROCESSES
The classic way we use automatic meter readings is simply to generate detailed consumption profiles. See my earlier articles on the heat-map display format, for example. But when it comes to routine reporting of exceptions and the diagnosis of anomalous energy performance, there's another key benefit to AMR.
To analyse energy performance (using tools such as cusum and regression) we must have data collected at successive equal intervals. I preach weekly as the sensible default. The group I was training on Thursday worked in dairy plants and are starting to adopt AMR with the advantage that they will be better able to synchronise their readings. They will also be able to take readings twice a day, at the end of each shift. However, their day and night shifts do different things: one does the manufacturing and the other does the cleaning. So my advice was to set up two separate parallel histories, one for each shift, aggregating both over the week and analysing them as distinct entities. The data for each will still be sequential and at regular intervals, but it will appear as if they are dealing with two factories: one purely manufacturing and the other continually cleaning itself. I expect what they will find is that the cleaning shift, being characterised by manual settings and operator discretion, will have much more variable behaviour and offer more scope for people-based initiatives, which will be thrown into starker relief by being evaluated as if production shifts had not happened.
This 'dual personality' approach to monitoring can be applied to buildings as well, notably in student accommodation, where the term-time and vacation consumption can be treated as if they were two separate establishments.
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6 JUNE 2017

RETHINKING REWINDS
Feedback from a recent 'Energy efficiency A to Z' course prompted me to review my material on electric motors in terms of whether one should replace or rewind failed motors. Conventional wisdom has long had it that rewinding is detrimental to energy efficiency; but it seems that view is out of date. A very thorough evaluation reported in 2003 (citation below) concludes that rewinding, when carried out in accordance with best practice, not only has a negligible impact on efficiency but may even improve it.
The decision whether or not to rewind actually comes down to factors which are quite case-specific and cannot be dictated by a one-size-fits-all policy. So for example the economic cost of waiting for a repair may force your hand, making replacement the only option. In non-urgent cases, an old motor might be replaced with a new one of substantially higher efficiency (and also possibly one better matched to the load if the original were oversized). But obviously if it is a special motor with a very long delivery time, rewinding may be your only choice.
Whatever the circumstances, if rewinding is contemplated it should be carried out in accordance with best practice, covering factors such as burn-out temperature, inspection and replacement of damaged laminations, and so on.
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31 MAY 2017

WHY, OH WHY...?
Regular readers will know of my obsession with False And Exaggerated Claimed Energy Savings (FAECES). But on two occasions I have come across perfectly legitimate products whose vendors have chosen to cite performance data which looks exaggerated, casting suspicion on something that actually deserves consideration. You need a bit of basic science to understand what they have done, but let me try to explain. In both cases, by coincidence, it comes down to latent heat.
In the first case we need to appreciate that the calorific value of a fuel - the amount of chemical energy it contains - can be quoted in two different ways. In the UK we habitually use the gross calorific value (GCV, or "higher heating value"). This accounts for the whole energy content, and because some of that energy is lost up the chimney, the efficiency of combustion (useful heat out divided by energy in) is always less than 100%. Typically with natural gas you cannot get much over 80% because the exhaust contains water vapour as a product of combustion, and for it to be in its vapour state it must have absorbed latent heat.
In continental Europe it is more common to state the net calorific value (NCV, or "lower heating value"). NCV is less than GCV because it disregards that part of the fuel's chemical energy that will be lost as latent heat in the exhaust vapour. Natural gas has an NCV/GCV ratio of 0.90; heavy oil, with its lower hydrogen content, has a ratio of 0.95 because it generates less water.
A glaring anomaly occurs when you have a gas-fired condensing boiler. Because it recovers the latent heat from the vapour in the exhaust, you may achieve an efficiency of perhaps 96% (dividing useful heat output by the gross calorific content). But should you choose to divide useful heat out by the NET calorific content, you'd get an efficiency supposedly of 106.7%, and that is what some reputable manufacturers quote. The result of this over-zealous marketing must surely be that sceptical customers (such as I hope you are, dear reader) will rule them out as frauds. They're not.
For the second example I'd like to thank reader Peter S., who drew my attention to a product that uses evaporative air cooling in place of conventional refrigeration. When the air is hot and dry, allowing it to absorb water will increase its relative humidity but reduce its temperature. This is because the water needs latent heat to become vapour, and taking that heat from the dry air reduces its temperature. It is a perfectly legitimate and effective method of reducing overheating but when a supplier claims a coefficient of performance of 20, they are bending the truth. The CoP is the ratio of cooling effect (thermal energy removed) to electrical energy put in: in evaporative cooling no thermal energy is actually removed, so it isn't fair to quote a CoP.
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24 MAY 2017

EXAGGERATED CLAIMS FOR ENERGY SAVING
I think we may be making some headway against the claims made for voltage reduction (VR), thanks to greater awareness of the concept of an energy balance. Put simply, reduced energy input results in reduced output; so when you see a Youtube video "proving" that you get savings on a fan motor from reduced voltage at various speeds, the reason is simply that it is a free-running fan (keep your eyes open during the opening sequence) and they aren't mentioning its reduced air throughput at reduced power.
But now that vendors are being challenged over the energy balance, they have had to change their tune. They now say that motor-driven equipment "becomes more efficient" at lower voltage, enabling it to sustain its output with less input energy. Can this be true? Let's take the case of a motor delivering its maximum output of 7.5 kW. If it has an IE3 rating it would be working with an efficiency of about 90%, requiring 8.33 kW of input power. Now let's suppose that VR saves 10% on the input power (bigger savings are sometimes claimed), taking it from 8.33 to 7.5 kW. That would be the same as the output power. Bingo! A one-hundred-percent efficient motor.
In reality of course, maintaining output at lower voltage will necessitate a higher current (watts being volts times amps) and this will increase the losses in the motor, making it less rather than more efficient, and raising rather than lowering the input power required for the given output.
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3 MAY 2017

YOUR ENERGY AWARENESS CAMPAIGN: IS IT TOAST?
One of the basic rules of energy motivation and awareness is to avoid self-defeating behaviours. With our hotel energy-saving conference coming up I have been thinking about that industry in particular and found a good example: toast-making machines.
In some hotel breakfast rooms you'll find a toast-making machine running on the servery table. In contrast to a pop-up toaster, these things transport your bread between radiant elements on a little conveyor belt and they don't shut down between uses. They are typically rated at 2.5 kW making each one the equivalent of say 50,000 idle phone chargers. At about Ł300 a year tops the cost penalty compared with a pop-up toaster is not huge. The significant point is that staff and guests are getting a subliminal message that it doesn't matter if energy-using appliances are left running -- and that has much more costly consequences.
This is a classic 'own goal': irritating or alienating sympathisers while vindicating those who feel entitled to make free with resources they consider themselves to have paid for.
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24 APRIL 2017

SOMETHING SMELLS FISHY
An item sent in by your fellow reader Ian B. highlights just how useful testimonials can be. A brochure promoting on-peak electric wall heaters as an alternative to gas central heating includes this quote: "warmth keeps for longer in the home and you don’t have the strange smell like from pipes". The first assertion is an evident falsehood because heat retention depends on the building fabric, not the type of heater; and and as for smelly pipes... If you are relying for testimonials on people who can't tell a central heating radiator from a blocked toilet, you have a problem.
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3 APRIL 2017

ERRORS IN SMART METERS
A reader contacted me after hearing in the press that lab tests had cast serious doubts on the accuracy of electricity meters (including so-called ‘smart’ meters) when feeding low-energy lamps, variable-speed drives and other equipment that generates electromagnetic interference.
I contacted my friend Kris Szajdzicki who has been designing and manufacturing meters for 40 years to discover that he was already on the case, reviewing and investigating the reports. He eventually concluded: that such measurement errors do occur; that their magnitude depends upon the current-sensing technology used by the meter; but that the effect may be negligible in normal situations in the domestic market. However, his view is that there is still potential for 'gross error' in unfavourable circumstances, particularly in industrial or commercial installations - or where there is deliberate intent to fool the meter.
Kris has kindly let me publish his report and you can download it here
HOW TO SELL SNAKE OIL: NO. 3
The UK government's Energy Technology List is an authoritative guide to products that save energy. It has to be rigorously policed because there is a tax advantage for certain energy users buying products that are on the ETL. Problem: how to get your bogus product onto the list? Here's a suggestion. Get a genuine, legitimate sister product included; then issue publicity material about it which segues seamlessly into a mention of the unlistable stuff.
You know who you are: thanks for the junk email that tipped me off to what you are doing.
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1 APRIL 2017 (APRIL FOOL'S DAY)

'WAVE' GOODBYE TO BLAND ELECTRICITY SUPPLIES
At Ł80 a pop in Harrods, according to last week's Economist, Svalbardi is the most expensive bottled water you can buy (it is made from Norwegian icebergs). We have long been used to brands like Perrier and Evian charging a premium for a commodity that most of us can get from the tap for almost nothing, so way back when the gas and electricity industries were privatised it must have irked energy suppliers that there was nothing they could do to differentiate their product from their competitors. "The same gas through the same pipes" is about as far from a unique selling proposition as it's possible to get; but all that is set to change in the electricity industry thanks to innovative UK startup Brain Power Limited.
BPL's marketing experts have taken inspiration from current trends such as voltage optimisation, variable frequency drives, and power quality monitors to create exciting new electricity supply options that they describe as "fit for the age of smart meters and artificial intelligence". Out is the bland sine-wave alternating current that has been the staple for public electricity supply in the UK for 70 years or more: "in" is a spectrum of waveforms ranging from the inexpensive square wave to the edgier sawtooth and, for the connoisseur, designer waveforms like 'ogive' which co-ordinates beautifully with Victorian architectural features. "The great thing about these non-sinusoidal waveforms is that they are really rich in higher harmonics", said a BPL spokesman.
There will be voltage options for every taste as well. 261 volts could appeal to musicians who will appreciate a voltage that equals the frequency of middle C. Nerds may go for 256 volts (because it is a "power" of 2). Initially available in single and three-phase supply only, BPL is rumoured to be releasing five and even thirteen-phase supplies after Brexit is complete, when customers will also be able to cast off the shackles of 50 cycles per second mains frequency.
Asked whether their catalogue will contain DC as well as AC options, BPL said that would be possible but only with batteries, which would be charged extra.
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20 MARCH 2017

ADVERTISEMENT FOR VOLTAGE OPTIMISATION WAS MISLEADING
EMSc, a supplier of voltage-reduction equipment, has had a complaint against it upheld by the Advertising Standards Authority in relation to an online advertisement for its ‘Powerstar’ range. The ASA said that EMSc should not claim a typical reduction regardless of the type of equipment fed by the mains supply. The advertisement was held to breach CAP Code rules 3.1 (misleading advertising) and 3.7, which states that when making such claims, marketers must hold documentary evidence “that consumers are likely to regard as objective and that are capable of objective substantiation”. The ASA considered that before making any efficiency savings claims for the equipment, Powerstar needed to hold evidence that supported the level of efficiency saving claimed “in the situations in which the equipment would be used”.
My view on voltage reduction is this: on the basis of a simple energy balance, reduced energy consumption will be achieved at the cost of reduced output. By the same token equipment with regulated or controlled output should use the same amount of input energy (in reality it may actually become less efficient thanks to increased resistive losses, and therefore draw MORE power at lower voltage; I show this in the case of an LED lamp in a video clip at http://youtube.com/vilnisvesma). It also annoys me that we rarely see a mention of the continuous standing loss incurred by the devices when energised.
Meanwhile the full ASA ruling, which must have implications for anyone promoting voltage "optimisation", can be seen at www.asa.org.uk: search their rulings for ‘EMSc’.
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25 JULY 2016

VOLTAGE REDUCTION
If you were considering whether voltage reduction will work for you, due diligence would entail surveying all your installed equipment and assigning it to the following classes:

Class 1: Unregulated appliances such as filament light bulbs and certain motor-driven equipment where the user can tolerate the reduced output associated with reduced power input;
Class 2: Controlled-output equipment such as (a) electric heaters with thermostatic control, where lower power consumption will be compensated for by longer running hours and (b) equipment such as pumps and conveyors which are required to do a certain amount of mechanical work and therefore always consume the corresponding amount of electricity plus a margin for losses;
Class 3: Equipment with built-in voltage stabilisation, for example computer power supplies and LED lighting; and
Class 4: Thermal equipment which requires a warm-up period (kilns, ovens, kettles, laser printers, etc) where the longer warm-up period at lower voltage results in higher overall heat loss through the operating cycle and hence higher, rather than lower, energy input.
Only class 1 appliances will use less energy. Class 4 appliances risk using more unless people are currently preheating them for longer than necessary. Class 2(a) will be unaffected, but in the cases of 2(b) and 3, their energy losses may increase slightly. This is because to maintain a defined power output at lower voltage they will need the same input power but at a higher current -- giving more resistive loss.
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4 JULY 2016

HOW TO SELL SNAKE OIL NO. 2: THE THREAT FROM M&V
If you are peddling dubious energy-saving products, independent verification is a threat but you can use it to your advantage. The smart snake-oil salesman mentions IPMVP (the best-known protocol) in his promotional literature, creating the impression that he has nothing to fear from independent scrutiny. Some go the extra mile and explain what adherence with IPMVP entails, making it look as disruptive and expensive as possible. This not only reinforces the false impression of openness, it further discourages buyers from actually doing it.
Of course, some customers may insist on using M&V, but that is not necessarily a problem. Randomness, experimental error, and flawed tests will occasionally throw up apparent successes which a verifier cannot find fault with. Conceal the adverse results, and publish the favourable ones -- citing the name of the verifier if he or she is certified.
With even a single verified "success", you can misrepresent the results as proving that the technology works in general, because hardly anybody knows that IPMVP is not valid for generic testing.
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30 JUNE 2016

HOW TO SELL SNAKE OIL NO. 1: DEALING WITH EXPERTS
Experts can be a nuisance, as we all know. There you are, minding your own business, promoting a bogus product in an on-line forum and up pops an expert challenging the science behind your claims. No problem: just dismiss them as “self-appointed” experts, and castigate them for having closed minds. Remind them that people used to think the Earth was flat.
On another occasion you might get a technical challenge in a conference or other live event with a skeptical audience. Again, no problem: just say that you are not a scientist yourself, and refer people to your case histories.
Your potential customers, fortunately, are themselves unlikely to be sufficiently confident of their own scientific knowledge to challenge you effectively. Just make sure they don't find out about the training I provide.
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1 APRIL 2016 (APRIL FOOL'S DAY)
In developments reminiscent of car-industry scandals, Endomagno Ltd has ordered a total product recall of its bolt-on fuel-treatment magnets after two serious incidents at customers' premises.
Such magnets are commonly claimed to improve consumption by aligning the gas molecules, and the incidents appear to involve the alignment effect being so strong that the gas has actually crystallised in the burner. Why this has started to happen now is not clear (the product literature points out that the Romans used lode-stones to improve the heat output of hypocausts) but my theory is that it relates to the introduction of new microcrystalline neodymium magnets in what the company describes as "a certain configuration". Chaos entanglement theory says that these may interact with quantum nanoparticles in the gas stream in unpredictable ways.
The product recall presents a significant logistical problem for Endomagno. Although the magnets are easy to attach using gaffer tape, they cannot be removed by the customer without invalidating the product's Korean patent. This means sending a technician to every site and as a market leader in magnetic fuel treatment they have nearly seven users.
Endomagno's marketing director, Frank Lee Beaugusse, told me that the company is urgently investigating two alternative technologies. The most promising is a unipolar magnet, which only has a north pole, but they are also testing more conventional magnets with east and west (rather than north and south) poles. Comparative evaluation and testing will be carried out by Laboratoires Garnier.
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14 MARCH 2016

RADIATOR OUTPUT ENHANCERS
There is a class of product that claims to save energy by enhancing the output of central heating radiators. Some are small fan units; but one, the Energy Squirrel, is just a stick-on metal plate (thanks to reader Nicola Terry for the tip-off there). Then of course we have the magic additives which improve heat transfer on the water side.
Many are sold on the basis that you will save energy because the room "will heat up faster". Could there be any truth in this? In principle, there might be. But savings would only arise you optimised the start time of the heating to take advantage of the shorter warm-up period. If you left the start time unchanged the result would actually be increased consumption with the room reaching its daytime control temperature prematurely.
However, from simulations I have run under typical conditions, you'd need to boost radiator output by half to yield a paltry 3% fuel saving. See the full article at enmanreg.org/radspeed.
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13 JANUARY 2015

HOW TO WASTE ENERGY NO. 9: ENERGY AUDITS
For the keen energy waster faced with demands to have an energy audit, it is vital to employ an incompetent assessor -- one who can be expected to follow these principles:
1. Just turn up at site with a clipboard and start counting light fittings.
2. Never analyse historical data to identify anomalies that you could productively focus on during site visits.
3. Base your report on a previous one for a different client. A good trick is to use 'find and replace' to change the name in the body of the text, but overlook where it appears in headers and footers.
4. Always make at least ten recommendations, even if there is only one substantial worthwhile measure.
5. Always include recommendations for LED lighting and voltage reduction.
6. Over-estimate the savings expected from each recommendation.
7. Ignore any possibility of interactions between recommended measures.
8. Never obtain actual installation costs. Reverse-engineer them: take the annual savings and multiply by an assumed payback period.
Of course as a client, the keen energy waster has their own part to play in making the audit a futile exercise. Here are some tips:
1. Do not let anybody in the organization know about the audit visit.
2. Render all relevant data and drawings inaccessible.
3. When you receive the report, ignore it.
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15 OCOBER 2014

HOW TO WASTE ENERGY NO. 8: ROAD TRANSPORT
Transport in all its forms provides excellent opportunities to waste energy. Here are a few related to car, van and truck use:
1. Never arrange a telephone call or video conference if you can drive to a meeting instead. Driving long hours shows you are working hard.
2. Never share a car journey.
3. Make sure drivers have not got clear directions to their destinations, so that they get lost.
4. Use oversized goods vehicles whenever possible, and avoid consolidating loads to improve load factor.
5. Do not plan freight movements. For example if back-loads are available, it is better to send out empty vehicles to fetch them.
6. Never optimize multi-drop delivery routes.
7. Never give drivers training. Encourage them to accelerate hard, drive too fast in too low a gear, brake harshly, and idle their engines for long periods.
8. Fit the wrong kinds of tyres and run them at the wrong pressures.
9. Neglect maintenance of tracking and brakes: as well as wasting fuel you can spend extra on tyres and brake parts.
10. Do not monitor mileages, loadings or fuel purchases.
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7 AUGUST 2014

HOW TO WASTE ENERGY NO. 7: METER READING
A big part of wasting energy is not knowing how much you use, when, where or for what. Most keen energy wasters rely on their energy suppliers not read their meters for them, but here are some top tips for those who want to be proactively bad: 1. Make it difficult to get access, for example by installing meters at height, or leaving the keys to the meter room with an obnoxious jobsworth.
2. Try to have meters installed in positions where you cannot see their dials.
3. Never have a reliable check-reading taken by somebody who knows what they are doing.
4. Do not create a meter schedule; if you have one, don't keep it up to date.
5. Do not try to find out what each meter serves.
6. If in doubt about units of measurement or scale multiplier factors, make whatever assumptions you like.
7. When a meter is swapped out, dispose of the old one without noting its final reading.
8. Do not train anybody to read meters.
9. Do not appoint stand-ins to cover for sickness or holiday absence.
10. Allow meter readers to be lax about when they take readings, and let them record the date they were supposed to take the readings rather than the actual date and time.
11. Allow meter readers to include or ignore decimal fractions as they feel inclined, if possible being inconsistent between visits to the same meter.
12. Rely on paper returns, and lose them.
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22 JULY 2014

HOW TO WASTE ENERGY NO. 6: AIR CONDITIONING
The hot weather brings with it demands for air conditioning, and with that comes a whole raft of excellent ways for organizations to waste energy. Here are my top ten hot tips:
1. Don't argue when people ask for rooms to be cooled to 20C rather than the more sensible 27C. Every degree reduction in set-point adds 10-15% to the electricity used for cooling, and you may even hit the jackpot of some people turning on electric heaters as well.
2. Encourage people to leave the windows open with the air-conditioning on. This allows warm air in and expensively-cooled air out, more or less guaranteeing that the air conditioning will have to run flat out without reaching the desired internal temperature.
3. If it is not possible to leave the windows or doors open, minimise the recirculation of ventilation air.
4. Do not take advantage of lower overnight outdoor temperatures to pre-cool occupied spaces.
5. Encourage people to leave idle electrical items running, to increase the heat gains. Desk fans are an excellent example for those who can appreciate the irony: by creating air movement they make the occupants feel more comfortable, while continuously heating the air a little.
6. Believe your IT department and equipment suppliers when they say their kit needs to be housed at 16C (the idea that it might be designed to operate in tropical climates is ridiculous).
7. In computer rooms have the equipment racks all in the same space, so that their warm extract air mixes with the chilled air needed for intakes. Under no circumstances partition the space to separate cold and warm air.
8. If possible, house people and equipment racks in the same space as if they needed and/or could tolerate the same conditions.
9. Do not shield windows from direct sunlight.
10. Always use artificial cooling when increasing the ambient fresh air supply would do the job equally well.
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15 JULY 2014

STRUGGLING TO VERIFY SAVINGS?
When people ask me for advice on how to verify energy savings, it is usually because their analysis is not giving the results they expected. Often they have left it too late, developing a methodology after the event or even making it up as they go along. So if you are contemplating an energy-saving project the first plea I would make is this: agree a measurement and verification plan between the interested parties before the project starts. That way, everyone is forced to think about the calculation methodology and (just as importantly) focus on what data will be needed, who will collect it, and even how much uncertainty there is likely to be in the conclusions. It also pays to think about what non-routine changes might occur (patterns of occupation, extensions, demolitions, etc) and agree how those will be factored in if they occur.
Sometimes, fortunately, it is possible to rescue the verification of a project where the “shoot first, ask questions later” approach has been used. To achieve a resolution one needs two things: first a willingness on both sides to accept a retrospective definition of procedure; and secondly, at least some accurate prior consumption data. That consumption data can, however, be sparse, so the presence of a lot of estimates (a common situation) need not necessarily be a problem. The analysis in such circumstances is done using a technique called “back-casting”.
Recall that in a normal evaluation, accurate and complete pre-project baseline data are needed so as to establish the prior relationship between consumption and relevant independent driving factors (such as degree days, hours of darkness, production and so on). A formula is derived, typically using regression analysis, for predicting consumption from those driving factors. After the energy conservation measure (ECM) has been installed, that same baseline formula can be fed with driving-factor data and will yield an estimate of what consumption would have been in the absence of the ECM. The spread between this estimate and actual consumption is a measure of the ‘avoided’ energy consumption.
The back-casting method is different. It turns that logic on its head. Using post-ECM rather than pre-ECM measurements, a formula is developed which relates consumption to driving factors for the improved installation (rather than its original performance). Thus you can say that the analysis “baseline” period follows, rather than precedes, the ECM, which some people find odd. In this scenario, pre-ECM actual consumptions can be compared with what they would have been if the ECM had been active all along, and one would expect those actual consumptions to be higher than the model’s predictions (the opposite of the conventional approach where post-ECM consumptions turn out lower than the baseline model predicts).
Back-casting is no less valid as a method, but it enjoys one big advantage in that you only need two firm meter readings predating the ECM. They should be as far apart in time as possible, and you need to be able to retrieve driving-factor data spanning exactly the entire period between the meter readings, but if those conditions are met, your model formula can tell you what the expected consumption of the installation would have been over that entire period if the ECM had already been in place, and hence how much more was actually used in the absence of the ECM. This back-to-front approach is attractive because regular meter readings are generally easier to assure after the project than before.
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2 JULY 2014

HOW TO WASTE ENERGY NO. 5: MOTIVATION AND AWARENESS
People are your greatest asset in the battle against energy efficiency. Here are my top tips for disengaging your workforce:
1. Focus on trivial behaviours like leaving phone chargers plugged in.
2. Position climate change as a key consideration in order to maximise time-wasting and unproductive debate. Remember also that a message of fear will paralyse rather than stimulate action.
3. Over-promise with slogans like "together we can save the planet".
4. Give away branded mugs, coasters and other merchandise to enrage anyone bothered by waste of resources.
5. Do not canvass people for their opinions or ideas: remember the best instrument of communication is a megaphone.
6. If you do an opinion survey, use on-line techniques to be certain of reaching only those with computer access.
7. Use multiple-choice questions to be sure of missing responses you did not expect (obvious missing options also infuriate and alienate people).
8. Mount a high-profile launch event before you are ready with follow-on activities.
9. Appoint energy champions and leave them to sink or swim.
10. Be slow responding to staff suggestions.
11. If a suggestion does win an award, do not implement it.
12. Give individual cash awards: they can be wonderfully divisive if they are perceived as having gone to an undeserving winner.
13. If payouts are a share of savings, be ready to reduce the share for really successful ideas.
14. Don't forget everybody loves to be awarded a T-shirt with an energy-saving slogan on it.
15. Have a poster campaign.
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17 JUNE 2014

VOLTAGE REDUCTION PART 1: THE SHORT ANSWER
I am somewhat conscious of taking my life in my hands in this issue, but as so many readers have asked me what I think about voltage “optimisation” (or reduction, to use a more accurate term), let me answer the question with the following three guidelines, which apply to everything from heating and lighting to motive power:
1. If the equipment is regulated in any manner, don't expect voltage reduction to save energy.
2. If it is unregulated and you don’t mind reduced output, voltage reduction will save energy.
3. If it is a thermal application used on an intermittent cycle, voltage reduction will have a perverse effect, increasing energy consumption.
Editor's note: a more detailed explanation was given in Part 2 which has been omitted for lack of space here.
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10 June 2014

HOW TO WASTE ENERGY NO. 4: COMPRESSED AIR

1. Use compressed air for dusting off overalls, sweeping the yard and other cleaning duties. This not only wastes energy but blows debris into people's eyes.
2. If you have individual applications that require a higher pressure, run the entire system to satisfy them rather than fitting local boosters.
3. Set overall system pressure as high as you can (check that the safety valves are lifting frequently). As a rule of thumb, every 2 psi increase in operating pressure requires an additional 1% energy.
4. For low-grade duties such as tank agitation, use clean dried compressed air at high pressure rather than fitting local blowers.
5. Locate air inlets in the hottest place possible - remember every 6C increase in temperature adds 1% to the electricity consumption.
6. Never clean your air filters and avoid fitting low-loss types.
7. Make sure you do not dry the air.
8. Allow all your compressors to run in parallel, sharing the load however small.
9. Do not shut the system down if the premises are closed at night; but if you do, empty the air receiver at the end of the day so that it needs to be repressurised in the morning.
10. Leave air-receiver drain cocks cracked open.
11. Bypass the air receiver so that the compressors have difficulty matching the load and need to start and stop frequently. This is a marvellously inefficient mode of operation, and abrupt swings in pressure will also help to maximise the number of leaking joints and fittings.
12. Maximise pressure drops in the distribution system by undersizing all pipework.
13. Ignore leaks: fixing one probably causes another to appear somewhere else. If you have a routine for tagging and repairing leaks, do not repair any that people find. As well as wasting energy this will discourage people from reporting air loss.
14. When specifying new equipment, give preference to models that continuously vent air. Use air tools if electric equivalents are just as good.
15. Look for opportunities to use compressed air inappropriately. Dusting off overalls may not waste enough; try using it for cooling motor bearings that are running hot, or to cool people working in hot locations.
16. Do not recover free heat from compressor exhausts if it is possible to use heat from a boiler system (or better still, electric heaters) instead.
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03 June 2014

HOW TO WASTE ENERGY No. 3: LIGHTING

1. If your light fittings are the type with translucent diffusers, fill them with dead flies.
2. Avoid replacing tungsten-filament light bulbs with compact fluorescent equivalents. Although it is now illegal to sell most general lighting service (GLS) filament lamps, one can still buy "rough service" equivalents which have the great advantage of being even less energy-efficient.
3. Keep your external lighting on 24 hours a day. This encourages a culture of not caring about leaving things running when idle, and will help waste many times more energy than is used in the lights alone.
4. Also keep your internal lights on continuously, not least because doing so will increase the demand for air conditioning.
5. Provide excessive light levels in working areas and try to ensure that corridors and stairwells are even brighter (this removes one of the vital cues that prompt people to turn lights off when they leave empty rooms).
6. Be careless when specifying automatic lighting controls. Choose the wrong sensor technology, so as to maximise nuisance switching. This has a dual benefit - it encourages people to override the control, and it also antagonises them so they won't cooperate with other energy-saving initiatives.
7. In shared workplaces, paint over any labels identifying which switch controls which zone.
8. Choose automatic lighting controls with remote control handsets that cannot be understood without training. Then lose the instructions and the remotes.
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20 May 2014

HOW TO WASTE ENERGY No. 2: CONTROL SYSTEMS IN BUILDINGS

1. Set your frost-protection thermostat at too high a temperature.
2. Override your time control to run the plant continuously.
3. Set heating controls for maximum air temperature. The aim should be to make it so hot that occupants are forced to keep the doors and windows open, increasing the heat loss.
4. Alternatively, place a baked-potato oven under the space temperature sensor. This will hold the heating off and encourage people to bring in electric heaters.
5. If you have adaptive optimum-start control, set the timings as if it were a conventional time-switch (i.e. with start of occupancy at the same time you would previously have asked the plant to start up).
6. Also if you have adaptive optimum-start control, set a target temperature above the daytime control setpoint. The control will add more and more preheat every day because it never achieves the target temperature.
7. If you have air conditioning, set it to cool to a lower temperature than your heating, so that the two systems run simultaneously providing perfect comfort at infinite cost.
8. If you have humidity control, set it for the narrowest range conceivable. This will ensure you are nearly always either humidifying or dehumidifying.
9. Remove or jam the linkages on valve and damper actuators.
10. Do not commission your building energy management system; do not document the control philosophy or agreed settings; and as a backstop, lose the operating manuals.
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14 May 2014

HOW TO WASTE ENERGY No. 1: MOTOR-DRIVEN EQUIPMENT
1. When a motor fails, have it rewound, as this will reduce its efficiency.
2. If you need to replace a motor, use the cheapest and least efficient unit available (preferably oversized). Efficiency standards of new motors are being continuously improved, so you may need to shop on eBay.
3. Shift motors slightly on their mounting plates so that any drives and couplings are misaligned.
4. Ensure that drive-belts are slack. On multi-belt drives it can help to remove some belts. If possible, use the wrong kind of belt for the pulleys fitted.
5. Change pulley ratios to drive fans and pumps at higher speed: on centrifugal fans and pumps, a 20% speed increase adds over 70% to the load.
6. Neglect lubrication of bearings and gearboxes.
7. Allow equipment to run continuously, whether it is needed or not. This has the added advantage of accelerating wear and tear, and reducing your power factor.
8. When the driven equipment is decommissioned, at least leave its motor behind, energised and running.
9. In dirty environments, do not clean any debris off motor cooling air inlets. The extra resistance to air flow will increase mechanical losses in the motor and, as a bonus, accelerate its failure by causing it to overheat.
10. In situations where the mechanical output of a fixed-speed motor is controlled and regulated, run the motor below its rated voltage in order to increase the motor current and associated copper losses.
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9 May 2014

THE KILLER QUESTION FOR FINDING ENERGY OPPORTUNITIES
When you are looking for energy-saving opportunities, one of the most useful questions you can ask is: "how is that xxxx controlled?". Most energy-using systems benefit from good automatic control, whether it is temperatures or ventilation rates in a building, the output of a pump, or a lighting installation... You name it. Improving control is almost invariably a rapid-payback option, and uncovering incorrect control yields an instant win. This is one of the things I will be covering on 4 July in Manchester in my new workshop 'Finding energy-saving opportunities', and in Exeter on 5 June in the last of my 'Energy efficiency A to Z' courses. Details of all my planned events are at www.vesma.com/training, and remember to use the discount code EMR2012 to get your reader's discount.
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15 April 2014

DUTY-STANDBY ROTATION (1)
One of my clients, who operates computer data centres, asked his monitoring and targeting software supplier to conduct some pilot analyses using daily data. Cusum analysis of one particular circuit, which was feeding computer-room air cooling (CRAC) units, threw up an interesting observation: energy performance had been toggling between good and bad on the first of every month. This fact had been masked by the weather and variations in the quantity of energy consumed in the equipment racks, but once revealed, it was traced to the fact that they were alternating two banks of CRACs on a monthly cycle.
In situations like this, it pays to change the regime so that preference is given to the more energy-efficient plant. This has the secondary advantage that the standby set will have more maintenance life left in it when the lead set fails.
Cusum analysis is very good at providing insights like this, which is why I give it prominence in my training courses on monitoring and targeting.
DUTY-STANDBY ROTATION (2)
The other place one finds opportunities for instant savings is multi-boiler heating systems, where, too often, the firing sequence is deliberately rotated to give each boiler the lead and even out the wear. Apart from making no sense in terms of risk management (when one fails, all the survivors will be equally clapped-out) it also misses the opportunity to favour the unit with the highest combustion efficiency, and thereby consume less fuel for a given output of useful heat. Anyone unfamiliar with combustion efficiency and the opportunities that it offers can read up in the A to Z guide at www.vesma.com.
Combustion tuning is a good (and frequently-overlooked) opportunity for nearly all fuel users.
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1 APRIL 2014 (APRIL FOOL'S DAY)

CASE HISTORY OF THE MONTH
“How green can you be?” is the message from major energy users Gulley Bull Ltd, who undertook a multi-faceted approach to saving fuel in their head office. They combined magnetic fuel conditioning, which offered a 20% saving, with two kinds of boiler water treatment. One, a simple cartridge containing special stones developed by a NASA scientist, changes a property of water to improve heat transfer by 25%. The other is a patented secret additive which prevents large steam bubbles forming in the boiler and also improves efficiency by 25%. Their building had solid walls, and was hard to insulate, but their energy manager’s researches uncovered a paint additive containing ceramic microspheres which, because they contain a vacuum, act as perfect insulators and promised a 30% saving on their heating costs just from redecorating the offices. Finally, they replaced their heating timeswitch with a control which claims to cuts fuel use by 16% by intermittently turning off the heating, saving fuel without sacrificing comfort: “an ingenious idea which took our total fuel savings to 116%” according to Gulley Bull spokeswoman April Fulstryk.
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24 March 2014

SUPER-THIN INSULATION
Super-thin thermal insulation is in my sights at the moment. There are two categories: (a) multi-layer foil and fibre; and (b) paints or paint additives. The insulating effect of multi-layer systems is basically equal to the same thickness of whatever insulating fibre they use, but there is some additional advantage where they are installed with an air gap either side, since they create an extra cavity which has a certain thermal resistance. Their reflective foil will impart additional thermal resistance by preventing radiation from the hot to the cold face of the cavity. But note, however, that after filling with ordinary fibre, the hot and cold surfaces of the cavity can no longer see each other, and heat transfer is solely by conduction. So BOTH techniques eliminate radiative transfer across the cavity and the foil therefore imparts no advantage.
Insulating paints meanwhile, even if composed of material with high thermal resistivity, will have totally negligible effect because the insulating layer is microscopically thin (under 0.3mm by my calculations, based on coverage data in the advertisements). Claims that their ingredients reflect heat are unsound because those so-say reflective materials are buried in the paint layer; to reflect heat the SURFACE of the paint would need to act like a mirror to infra-red radiation.
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28 January 2014

EXAGGERATED CLAIMS FOR BOILER WATER TREATMENT
Stewart King from Aberdeenshire is among the readers who have alerted me to the rise of dubious claims for boiler water treatments in heating systems. In a new paper (www.vesma.com/downloads/op_treatment_savings.pdf) I show that the most you can expect from boiler cleaning (waterside and fireside combined) is probably about a 7% saving. I also should stress that ordinary good maintenance, including conventional descaling, is all you should need. If you have combustion test results of your own you can quantify the benefits of better maintenance using my Excel combustion calculator (www.vesma.com/tutorial/combust06.xls).
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18 April 2013

COMBUSTION EFFICIENCY TESTING
One of my readers has picked up on my advice about the fuel savings that can be had from independently testing the combustion efficiency achieved during boiler maintenance or between service visits. But he was worried that sampling of flue gases might come under the Gas Safe regulations (which they do not, by the way). He then quite reasonably contacted a training academy to see if they could provide instruction on flue-gas sampling, and they left him with the impression that there might be "health and safety issues" with the removal of sample-point plugs or caps.
As it happens the vast majority of flue sample points are just holes drilled in the exhaust flue pipe, and aren't closed anyway. As the exhaust gases are under slight suction at that point, any leakage will be into the flue rather than out into the boiler room. The exception would be where the sample point is after an induced-draft fan and in that case there will be a cap to prevent potentially-dangerous fumes escaping, the main danger being carbon monoxide, which normally should not be present.
The manufacturers of combustion analyzers promote them as being useable by a wide range of people, and their instruction manuals cover everything one needs to know about using them, including the necessity for replacing any cap or plug removed in the course of testing. If you are writing a method statement for people doing combustion tests, you might want to add a warning to avoid touching hot surfaces and a reminder that the business end of the probe will be hot after the test and shouldn't be touched or handled until it has cooled down. Sound like common sense? That's because it is, and this advice should not therefore be used in countries where people are legally required to be warned that coffee may be hot.
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1 April 2013 (APRIL FOOL'S DAY)

A LITTLE LIGHT READING...
Got your shopping basket and cheque-book ready? Let’s build that library of energy-management systems standards!
We’ll start with ISO 50001 “Energy management systems. Requirements with guidance for use” at Ł174 (or bizzarely, Ł12 less for the laminated version), and to make sure we implement it correctly, fork out Ł212 for ISO 50004 “Energy management systems. Guidance for the implementation, maintenance and improvement of an energy management system”. To help us understand it all we might add PD CEN/CLC TR 16103 “Energy management and energy efficiency. Glossary of terms”. That’s only an extra Ł152 but we can probably pass up on ISO 9229 “Thermal insulation. Vocabulary” (Ł200) especially as the subject seems also to be covered in the cheaper ISO 9251 “Thermal insulation. Heat transfer. Conditions and properties of materials. Vocabulary” at just Ł90.
Stay with me... Next, we will almost certainly want to do some energy audits. ISO 50002:2014 ED1 “Energy audits. Requirements with guidance for use” would seem to cover the ground, and at Ł103 it’s Ł5 less than the European Standard EN 16247-1 “Energy audits. General requirements”. But – decisions, decisions - EN 16247 also boasts other sub-standards: Part 2 for buildings at Ł192; Part 3, processes at Ł146; and Part 4, transport at Ł104 (the prices differ because they charge per page). If we want to use benchmarking we could pick up a copy of EN 16231 “Energy efficiency benchmarking methodology” for only Ł152, and thinking about the qualifications of the people doing the work we should add PAS 51215 “Energy efficiency assessment. Competence of a lead energy assessor. Specification”, which at Ł70 seems quite good value until you read it.
Swap your shopping basket for a trolley now, because we’re going to think about measuring and verifying our savings. To set the scene, let’s fork out Ł212 on EN 16212 “Energy Efficiency and Savings Calculation, Top-down and Bottom-up Methods”. Please suppress the thought that probably crept into your mind on seeing the words “up” and “bottom” in the title of one of these worthy publications, especially as we will see them again when we splash out Ł146 on CWA 15693 “Saving lifetimes of energy efficiency improvement measures in bottom-up calculations”. Then to be on the safe side let's get ISO 50015 “Energy management systems. Measurement and verification of energy performance of organizations. General principles and guidance” at Ł152, plus ISO 50006 “Energy management systems. Measuring energy performance using energy baselines and energy performance indicators. General principles and guidance” (Ł174). Nearly done... To make sure that our efforts to comply with all this stuff are up to scratch, let’s round off with Ł146 for ISO 50003 “Energy management systems. Requirements for bodies providing audit and certification of energy management systems”.
All in all, the bill could be over Ł2,000. There is no truth in the rumour that the International Standards Organisation, British Standards, and the Comité Européen de Normalisation are contemplating a joint venture to be called “ISO, BS and CEN Enterprises” or ISOBSCENE.
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12 March 2013

CORRECT USE OF AVERAGE DEGREE DAY FIGURES
From time to time I am asked for 20-year average degree-day figures, but from past years. A request like this always rings slight alarm bells because it is a bit like asking for a copy of a weather forecast that was broadcast a few months ago. Twenty-year averages are only supposed to be used for estimating future consumption, so only the most recent set is of any value.
It turns out that some users are using the averages for weather adjustment. They are taking the fuel used for heating in a given month, dividing by actual degree days (so far, so good) and then multiplying by the 20-year average degree days for that month. This gives them actual consumption adjusted to average weather. This is where an error creeps in. If they use a revised average each year, the result will change. Suppose the climate is getting milder: their adjusted fuel consumption will turn out less than it should, flattering the trend. To make the comparison fair one should use the same "average" degree-day number every year.
Just choosing a set of twenty-year average figures and sticking with them in perpetuity is one solution, but it isn't the best. It cures distortion of trends but it still leaves one unable to benchmark one building against another. To do that, the buildings' fuel consumptions should be normalised against a common fixed reference standard weather year, such as that shown at www.vesma.com/ddd/std-year.htm
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8 February 2013

PENALTY FOR EXCESSIVELY-TIGHT ENVIRONMENTAL CONTROL

The National Library of Scotland has achieved energy savings of 34% over two years. By careful experimentation with temperature and relative humidity settings, they found they could safely operate outside the limits stipulated in BS5454, whose requirements they had previously been following rigidly. According to NLS's Linda MacMillan, speaking at the Scottish Energy and Environment Conference on Tuesday, their consumption is down becasue with floating setpoints their dehumidification load is now "almost at nil" -- with no risk to their stock.
It seems that there had been no scientific basis to the limits for temperature and RH cited in BS5454, and it was probably a case of the air-conditioning industry dominating discussion in the drafting process.
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24 January 2013

OPTIMUM START CONTROL

Looking at how somebody had set the timing on a school heating system I noticed that their weekday schedule ran from 06:00 to 17:00. Normally this might be reasonable, but only if they were using a fixed-time control. In fact the control was an "optimiser", a timeswitch that automatically delays the startup time to prevent the building getting up to temperature earlier than necessary. Optimisers adapt to the characteristics of the systems they control, aiming to achieve a chosen target temperature at a specified time. Therein lay the users' error: their school was going to be snug and cosy at six o'clock every morning (at least two hours prematurely). An optimiser schedule must be set for the start of occupancy, not the plant startup time.
They had also set the optimiser target temperature at 21 degrees C. Two things wrong with that. The main thing is the risk that this target temperature will not be reached (because the normal thermostatic controls will prevent it getting there). If that happens, the optimiser will always think it has failed to allow enough preheat time, and will progressively start the plant earlier and earlier every day. The other bijou problemette with 21 C is that it is illegal. The Fuel and Electricity (Heating) (Control) (Amendment) Order 1980 generally prohibits artificial heating above 19 degrees.
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2 October 2012

HOT TIP - LITERALLY

Pretty well everyone has combustion apparatus (typically the burners on heating boilers) among the things they deal with as an energy manager. Management of combustion efficiency is a universal and often-neglected opportunity to save energy for next to nothing. Here's how.
A proportion of the heat released during combustion inevitably escapes up the chimney (a) because the exhaust gases are hot, and they contain either (b) any excess air that wasn't needed for combustion or (c) unburned fuel if insufficient air was supplied. Ensuring that burners are properly tuned during routine maintenance will ensure that the proportion of energy lost in this manner is minimised. It may only save a few percent, but the point is that the saving is free if you manage your maintenance contractor proactively: good burner tuning is just part of diligent maintenance.
Interesting, percentage losses in flue gases can be inferred using measurements of their oxygen and carbon monoxide levels, together with their temperature relative to the air in the boiler room. The apparatus to do this is perfectly affordable for many energy users, enabling them to keep an eye out for loss of efficiency.
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18 September 2012

ESTABLISHING ATTITUDES

One of the first steps in any energy motivation and awareness campaign is to establish what people in the organisation currently think about the subject. A questionnaire is one possible method, but designing an effective one is tricky. They quickly become bloated, and think about this: how often have you filled in a multiple-choice questionnaire and been frustrated because the answer you wanted to give was not one of the options?
I would like to suggest two guiding principles. Firstly limit yourself to four questions; and secondly make them open-ended. The four that I usually use are:

Do you think there is significant energy waste at work?
If so, whose job should it be to deal with it?
If you think it is important for the organisation to save energy, why?
What other aspects of your work are as important, or more important?
The answers to these questions are all you should need as a foundation. You may find the responses rather surprising, but that is good because it shows that your own preconceptions were wrong.
If you work for a large organisation you probably dread having to read and analyse all the free-text responses. But there is a way around that problem: invite people to discuss the questions with their friends at work and submit a group view. That not only reduces your workload, but also raises the profile of the subject, which is after all what you are trying to do.
The next step would be to publish the conclusions promptly in a half-page summary, focussing on those areas of consensus which are helpful or neutral to your campaign. This feedback serves several purposes, one of which is that it subtly helps to align everyone's attitudes through the phenomenon called 'social proof', the unconscious tendency to behave like other people whom we regard as similar to us. And of course the effect works on everyone who hears the feedback, not just those who responded to the survey.
But don't do the survey in isolation: have your next few steps planned out. Be ready, for example, to have people suddenly start making more suggestions. A positive groundswell of opinion will be wasted if your campaign cannot respond smoothly.
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16 August 2012

BAD PRACTICE GUIDE: TWELVE TIPS FOR DESIGNING A REALLY AWFUL ENERGY DASHBOARD
1. Make maximum use of decoration. Bright colours, gradient fills, 3-D effects, borders and boxes (preferably with shadows) are essential because your readers have a mental age of six and are easily bored by information.
2. Put your logo prominently on the top left-hand corner of the screen, because that is prime real estate. It is where the user’s eyes will usually land first, and your brand identity is surely the most important piece of information on the screen.
3. Pack in as much data as you can. Empty space on a dashboard is a clear signal that you have not been working very, very hard.
4. Pie charts are the perfect choice for presenting comparative data because (a) there is a limit to the number of items that they can portray, and (b) the human eye finds it difficult to judge the relative areas of the segments (use 3-D pie charts to make it even harder). Labelling the segments with text around the perimeter, connected by leader lines, is an excellent way to make the graphic shrink to an unusable size, but you may prefer to use a colour-coded key which will significantly slow down interpretation of the chart — and ideally render it ambiguous or even unusable for anyone with impaired colour vision.
5. Dial gauges are a very good way to use more space than necessary to report a single numerical value. Using a dial proves that you are clever and understand the dashboard metaphor. If users need to compare a selection of different values, an array of ‘rev counter’ gauges is an attractive way to prevent them doing so easily.
6. Make liberal use of vertical text for chart labels, to make users crick their necks (having a mix of upward and downward text directions really shows your disregard for their comfort). Text must be in a mixture of large and tiny fonts: large to use up space, small to make things difficult to read, and the mixture to make the presentation uglier in case you have otherwise failed to make it garish enough.
7. When reporting two or more associated variables, stacked column graphs are an excellent way to conceal trends and comparative values. If possible put the values with most variability at the bottom of the stack, to ensure that the values of the second and subsequent tranches are as difficult as possible to follow.
8. If you are displaying a history of monthly consumption values, use a column-chart format overlaying one year on another (all Januaries together, and so on) to prevent the long-term trend being visible and to hide what happens at the turn of the year. With the right choice of column colours, moreover, you can arbitrarily emphasise one year in particular. Never use a simple line chart to portray the history of a measured value, because it makes it too easy to spot trends.
9. Always report numerical values to as many decimal places as possible.
10. A table should always be presented as a grid with lines separating the rows and columns, because the recipients, who are stupid, will not be able to read it otherwise. They may not even realise that it is a table. Redundant separators are also an excellent way to force the use of unreadbly-small type.
11. Be sure to restart all reports and charts at the beginning of the year and discard any earlier data. It is vital to avoid moving averages, rolling totals and other representations that make it easy to perceive longer-term trends. Instead, be sure to reset all averages and cumulative totals to zero each year (or on a monthly, weekly or daily basis if it is important to disrupt the continuity of shorter-term reports).
12. Avoid giving any indication of context or significance, such as whether a reported value is within acceptable limits, on a trend in a particular direction, subject to high variability, and so on. Under no circumstances should you compare actual with expected values, much less prioritise any deviations or hide instances that are not significant. Your invariable aim, when reporting a numerical value, should be to have the user say: “so what?”.
... Joking aside, if you are interested in how to do the job well, I heartily recommend the textbook 'Information Dashboard Design' by Stephen Few, who is a strong advocate of clean, lean and uncluttered displays and offers a wealth of design tips.
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Allow meter readers to include or ignore decimal fractions as they feel inclined, if possible being inconsistent between visits to the same meter.

12. Rely on paper returns, and lose them.

22 JULY 2014

HOW TO WASTE ENERGY NO. 6: AIR CONDITIONING

The hot weather brings with it demands for air conditioning, and with that comes a whole raft of excellent ways for organizations to waste energy. Here are my top ten hot tips:

1. Don't argue when people ask for rooms to be cooled to 20C rather than the more sensible 27C. Every degree reduction in set-point adds 10-15% to the electricity used for cooling, and you may even hit the jackpot of some people turning on electric heaters as well.

2. Encourage people to leave the windows open with the air-conditioning on. This allows warm air in and expensively-cooled air out, more or less guaranteeing that the air conditioning will have to run flat out without reaching the desired internal temperature.

3. If it is not possible to leave the windows or doors open, minimise the recirculation of ventilation air.

4. Do not take advantage of lower overnight outdoor temperatures to pre-cool occupied spaces.

5. Encourage people to leave idle electrical items running, to increase the heat gains. Desk fans are an excellent example for those who can appreciate the irony: by creating air movement they make the occupants feel more comfortable, while continuously heating the air a little.

6. Believe your IT department and equipment suppliers when they say their kit needs to be housed at 16C (the idea that it might be designed to operate in tropical climates is ridiculous).

7. In computer rooms have the equipment racks all in the same space, so that their warm extract air mixes with the chilled air needed for intakes. Under no circumstances partition the space to separate cold and warm air.

8. If possible, house people and equipment racks in the same space as if they needed and/or could tolerate the same conditions.

9. Do not shield windows from direct sunlight.

10. Always use artificial cooling when increasing the ambient fresh air supply would do the job equally well.

15 JULY 2014

STRUGGLING TO VERIFY SAVINGS?

When people ask me for advice on how to verify energy savings, it is usually because their analysis is not giving the results they expected. Often they have left it too late, developing a methodology after the event or even making it up as they go along. So if you are contemplating an energy-saving project the first plea I would make is this: agree a measurement and verification plan between the interested parties before the project starts. That way, everyone is forced to think about the calculation methodology and (just as importantly) focus on what data will be needed, who will collect it, and even how much uncertainty there is likely to be in the conclusions. It also pays to think about what non-routine changes might occur (patterns of occupation, extensions, demolitions, etc) and agree how those will be factored in if they occur.

Sometimes, fortunately, it is possible to rescue the verification of a project where the “shoot first, ask questions later” approach has been used. To achieve a resolution one needs two things: first a willingness on both sides to accept a retrospective definition of procedure; and secondly, at least some accurate prior consumption data. That consumption data can, however, be sparse, so the presence of a lot of estimates (a common situation) need not necessarily be a problem. The analysis in such circumstances is done using a technique called “back-casting”.

Recall that in a normal evaluation, accurate and complete pre-project baseline data are needed so as to establish the prior relationship between consumption and relevant independent driving factors (such as degree days, hours of darkness, production and so on). A formula is derived, typically using regression analysis, for predicting consumption from those driving factors. After the energy conservation measure (ECM) has been installed, that same baseline formula can be fed with driving-factor data and will yield an estimate of what consumption would have been in the absence of the ECM. The spread between this estimate and actual consumption is a measure of the ‘avoided’ energy consumption.

The back-casting method is different. It turns that logic on its head. Using post-ECM rather than pre-ECM measurements, a formula is developed which relates consumption to driving factors for the improved installation (rather than its original performance). Thus you can say that the analysis “baseline” period follows, rather than precedes, the ECM, which some people find odd. In this scenario, pre-ECM actual consumptions can be compared with what they would have been if the ECM had been active all along, and one would expect those actual consumptions to be higher than the model’s predictions (the opposite of the conventional approach where post-ECM consumptions turn out lower than the baseline model predicts).

Back-casting is no less valid as a method, but it enjoys one big advantage in that you only need two firm meter readings predating the ECM. They should be as far apart in time as possible, and you need to be able to retrieve driving-factor data spanning exactly the entire period between the meter readings, but if those conditions are met, your model formula can tell you what the expected consumption of the installation would have been over that entire period if the ECM had already been in place, and hence how much more was actually used in the absence of the ECM. This back-to-front approach is attractive because regular meter readings are generally easier to assure after the project than before.

2 JULY 2014

HOW TO WASTE ENERGY NO. 5: MOTIVATION AND AWARENESS

People are your greatest asset in the battle against energy efficiency. Here are my top tips for disengaging your workforce:

1. Focus on trivial behaviours like leaving phone chargers plugged in.

2. Position climate change as a key consideration in order to maximise time-wasting and unproductive debate. Remember also that a message of fear will paralyse rather than stimulate action.

3. Over-promise with slogans like "together we can save the planet".

4. Give away branded mugs, coasters and other merchandise to enrage anyone bothered by waste of resources.

5. Do not canvass people for their opinions or ideas: remember the best instrument of communication is a megaphone.

6. If you do an opinion survey, use on-line techniques to be certain of reaching only those with computer access.

7. Use multiple-choice questions to be sure of missing responses you did not expect (obvious missing options also infuriate and alienate people).

8. Mount a high-profile launch event before you are ready with follow-on activities.

9. Appoint energy champions and leave them to sink or swim.

10. Be slow responding to staff suggestions.

11. If a suggestion does win an award, do not implement it.

12. Give individual cash awards: they can be wonderfully divisive if they are perceived as having gone to an undeserving winner.

13. If payouts are a share of savings, be ready to reduce the share for really successful ideas.

14. Don't forget everybody loves to be awarded a T-shirt with an energy-saving slogan on it.

15. Have a poster campaign.

17 JUNE 2014

VOLTAGE REDUCTION PART 1: THE SHORT ANSWER

I am somewhat conscious of taking my life in my hands in this issue, but as so many readers have asked me what I think about voltage “optimisation” (or reduction, to use a more accurate term), let me answer the question with the following three guidelines, which apply to everything from heating and lighting to motive power:

1. If the equipment is regulated in any manner, don't expect voltage reduction to save energy.
2. If it is unregulated and you don’t mind reduced output, voltage reduction will save energy.
3. If it is a thermal application used on an intermittent cycle, voltage reduction will have a perverse effect, increasing energy consumption.

Editor's note: a more detailed explanation was given in Part 2 which has been omitted for lack of space here.

10 June 2014

HOW TO WASTE ENERGY NO. 4: COMPRESSED AIR

1. Use compressed air for dusting off overalls, sweeping the yard and other cleaning duties. This not only wastes energy but blows debris into people's eyes.

2. If you have individual applications that require a higher pressure, run the entire system to satisfy them rather than fitting local boosters.

3. Set overall system pressure as high as you can (check that the safety valves are lifting frequently). As a rule of thumb, every 2 psi increase in operating pressure requires an additional 1% energy.

4. For low-grade duties such as tank agitation, use clean dried compressed air at high pressure rather than fitting local blowers.

5. Locate air inlets in the hottest place possible - remember every 6C increase in temperature adds 1% to the electricity consumption.

6. Never clean your air filters and avoid fitting low-loss types.

7. Make sure you do not dry the air.

8. Allow all your compressors to run in parallel, sharing the load however small.

9. Do not shut the system down if the premises are closed at night; but if you do, empty the air receiver at the end of the day so that it needs to be repressurised in the morning.

10. Leave air-receiver drain cocks cracked open.

11. Bypass the air receiver so that the compressors have difficulty matching the load and need to start and stop frequently. This is a marvellously inefficient mode of operation, and abrupt swings in pressure will also help to maximise the number of leaking joints and fittings.

12. Maximise pressure drops in the distribution system by undersizing all pipework.

13. Ignore leaks: fixing one probably causes another to appear somewhere else. If you have a routine for tagging and repairing leaks, do not repair any that people find. As well as wasting energy this will discourage people from reporting air loss.

14. When specifying new equipment, give preference to models that continuously vent air. Use air tools if electric equivalents are just as good.

15. Look for opportunities to use compressed air inappropriately. Dusting off overalls may not waste enough; try using it for cooling motor bearings that are running hot, or to cool people working in hot locations.

16. Do not recover free heat from compressor exhausts if it is possible to use heat from a boiler system (or better still, electric heaters) instead.

03 June 2014

HOW TO WASTE ENERGY No. 3: LIGHTING

1. If your light fittings are the type with translucent diffusers, fill them with dead flies.

2. Avoid replacing tungsten-filament light bulbs with compact fluorescent equivalents. Although it is now illegal to sell most general lighting service (GLS) filament lamps, one can still buy "rough service" equivalents which have the great advantage of being even less energy-efficient.

3. Keep your external lighting on 24 hours a day. This encourages a culture of not caring about leaving things running when idle, and will help waste many times more energy than is used in the lights alone.

4. Also keep your internal lights on continuously, not least because doing so will increase the demand for air conditioning.

5. Provide excessive light levels in working areas and try to ensure that corridors and stairwells are even brighter (this removes one of the vital cues that prompt people to turn lights off when they leave empty rooms).

6. Be careless when specifying automatic lighting controls. Choose the wrong sensor technology, so as to maximise nuisance switching. This has a dual benefit - it encourages people to override the control, and it also antagonises them so they won't cooperate with other energy-saving initiatives.

7. In shared workplaces, paint over any labels identifying which switch controls which zone.

8. Choose automatic lighting controls with remote control handsets that cannot be understood without training. Then lose the instructions and the remotes.

20 May 2014

HOW TO WASTE ENERGY No. 2: CONTROL SYSTEMS IN BUILDINGS

1. Set your frost-protection thermostat at too high a temperature.

2. Override your time control to run the plant continuously.

3. Set heating controls for maximum air temperature. The aim should be to make it so hot that occupants are forced to keep the doors and windows open, increasing the heat loss.

4. Alternatively, place a baked-potato oven under the space temperature sensor. This will hold the heating off and encourage people to bring in electric heaters.

5. If you have adaptive optimum-start control, set the timings as if it were a conventional time-switch (i.e. with start of occupancy at the same time you would previously have asked the plant to start up).

6. Also if you have adaptive optimum-start control, set a target temperature above the daytime control setpoint. The control will add more and more preheat every day because it never achieves the target temperature.

7. If you have air conditioning, set it to cool to a lower temperature than your heating, so that the two systems run simultaneously providing perfect comfort at infinite cost.

8. If you have humidity control, set it for the narrowest range conceivable. This will ensure you are nearly always either humidifying or dehumidifying.

9. Remove or jam the linkages on valve and damper actuators.

10. Do not commission your building energy management system; do not document the control philosophy or agreed settings; and as a backstop, lose the operating manuals.

14 May 2014

HOW TO WASTE ENERGY No. 1: MOTOR-DRIVEN EQUIPMENT

1. When a motor fails, have it rewound, as this will reduce its efficiency.

2. If you need to replace a motor, use the cheapest and least efficient unit available (preferably oversized). Efficiency standards of new motors are being continuously improved, so you may need to shop on eBay.

3. Shift motors slightly on their mounting plates so that any drives and couplings are misaligned.

4. Ensure that drive-belts are slack. On multi-belt drives it can help to remove some belts. If possible, use the wrong kind of belt for the pulleys fitted.

5. Change pulley ratios to drive fans and pumps at higher speed: on centrifugal fans and pumps, a 20% speed increase adds over 70% to the load.

6. Neglect lubrication of bearings and gearboxes.

7. Allow equipment to run continuously, whether it is needed or not. This has the added advantage of accelerating wear and tear, and reducing your power factor.

8. When the driven equipment is decommissioned, at least leave its motor behind, energised and running.

9. In dirty environments, do not clean any debris off motor cooling air inlets. The extra resistance to air flow will increase mechanical losses in the motor and, as a bonus, accelerate its failure by causing it to overheat.

10. In situations where the mechanical output of a fixed-speed motor is controlled and regulated, run the motor below its rated voltage in order to increase the motor current and associated copper losses.

9 May 2014

THE KILLER QUESTION FOR FINDING ENERGY OPPORTUNITIES

When you are looking for energy-saving opportunities, one of the most useful questions you can ask is: "how is that xxxx controlled?". Most energy-using systems benefit from good automatic control, whether it is temperatures or ventilation rates in a building, the output of a pump, or a lighting installation... You name it. Improving control is almost invariably a rapid-payback option, and uncovering incorrect control yields an instant win. This is one of the things I will be covering on 4 July in Manchester in my new workshop 'Finding energy-saving opportunities', and in Exeter on 5 June in the last of my 'Energy efficiency A to Z' courses. Details of all my planned events are at www.vesma.com/training, and remember to use the discount code EMR2012 to get your reader's discount.

15 April 2014

DUTY-STANDBY ROTATION (1)

One of my clients, who operates computer data centres, asked his monitoring and targeting software supplier to conduct some pilot analyses using daily data. Cusum analysis of one particular circuit, which was feeding computer-room air cooling (CRAC) units, threw up an interesting observation: energy performance had been toggling between good and bad on the first of every month. This fact had been masked by the weather and variations in the quantity of energy consumed in the equipment racks, but once revealed, it was traced to the fact that they were alternating two banks of CRACs on a monthly cycle.

In situations like this, it pays to change the regime so that preference is given to the more energy-efficient plant. This has the secondary advantage that the standby set will have more maintenance life left in it when the lead set fails.

Cusum analysis is very good at providing insights like this, which is why I give it prominence in my training courses on monitoring and targeting.

DUTY-STANDBY ROTATION (2)

The other place one finds opportunities for instant savings is multi-boiler heating systems, where, too often, the firing sequence is deliberately rotated to give each boiler the lead and even out the wear. Apart from making no sense in terms of risk management (when one fails, all the survivors will be equally clapped-out) it also misses the opportunity to favour the unit with the highest combustion efficiency, and thereby consume less fuel for a given output of useful heat. Anyone unfamiliar with combustion efficiency and the opportunities that it offers can read up in the A to Z guide at www.vesma.com.

Combustion tuning is a good (and frequently-overlooked) opportunity for nearly all fuel users.

1 APRIL 2014 (APRIL FOOL'S DAY)

CASE HISTORY OF THE MONTH

“How green can you be?” is the message from major energy users Gulley Bull Ltd, who undertook a multi-faceted approach to saving fuel in their head office. They combined magnetic fuel conditioning, which offered a 20% saving, with two kinds of boiler water treatment. One, a simple cartridge containing special stones developed by a NASA scientist, changes a property of water to improve heat transfer by 25%. The other is a patented secret additive which prevents large steam bubbles forming in the boiler and also improves efficiency by 25%. Their building had solid walls, and was hard to insulate, but their energy manager’s researches uncovered a paint additive containing ceramic microspheres which, because they contain a vacuum, act as perfect insulators and promised a 30% saving on their heating costs just from redecorating the offices. Finally, they replaced their heating timeswitch with a control which claims to cuts fuel use by 16% by intermittently turning off the heating, saving fuel without sacrificing comfort: “an ingenious idea which took our total fuel savings to 116%” according to Gulley Bull spokeswoman April Fulstryk.

24 March 2014

SUPER-THIN INSULATION

Super-thin thermal insulation is in my sights at the moment. There are two categories: (a) multi-layer foil and fibre; and (b) paints or paint additives. The insulating effect of multi-layer systems is basically equal to the same thickness of whatever insulating fibre they use, but there is some additional advantage where they are installed with an air gap either side, since they create an extra cavity which has a certain thermal resistance. Their reflective foil will impart additional thermal resistance by preventing radiation from the hot to the cold face of the cavity. But note, however, that after filling with ordinary fibre, the hot and cold surfaces of the cavity can no longer see each other, and heat transfer is solely by conduction. So BOTH techniques eliminate radiative transfer across the cavity and the foil therefore imparts no advantage.

Insulating paints meanwhile, even if composed of material with high thermal resistivity, will have totally negligible effect because the insulating layer is microscopically thin (under 0.3mm by my calculations, based on coverage data in the advertisements). Claims that their ingredients reflect heat are unsound because those so-say reflective materials are buried in the paint layer; to reflect heat the SURFACE of the paint would need to act like a mirror to infra-red radiation.

28 January 2014

EXAGGERATED CLAIMS FOR BOILER WATER TREATMENT

Stewart King from Aberdeenshire is among the readers who have alerted me to the rise of dubious claims for boiler water treatments in heating systems. In a new paper (www.vesma.com/downloads/op_treatment_savings.pdf) I show that the most you can expect from boiler cleaning (waterside and fireside combined) is probably about a 7% saving. I also should stress that ordinary good maintenance, including conventional descaling, is all you should need. If you have combustion test results of your own you can quantify the benefits of better maintenance using my Excel combustion calculator (www.vesma.com/tutorial/combust06.xls).

18 April 2013

COMBUSTION EFFICIENCY TESTING

One of my readers has picked up on my advice about the fuel savings that can be had from independently testing the combustion efficiency achieved during boiler maintenance or between service visits. But he was worried that sampling of flue gases might come under the Gas Safe regulations (which they do not, by the way). He then quite reasonably contacted a training academy to see if they could provide instruction on flue-gas sampling, and they left him with the impression that there might be "health and safety issues" with the removal of sample-point plugs or caps.

As it happens the vast majority of flue sample points are just holes drilled in the exhaust flue pipe, and aren't closed anyway. As the exhaust gases are under slight suction at that point, any leakage will be into the flue rather than out into the boiler room. The exception would be where the sample point is after an induced-draft fan and in that case there will be a cap to prevent potentially-dangerous fumes escaping, the main danger being carbon monoxide, which normally should not be present.

The manufacturers of combustion analyzers promote them as being useable by a wide range of people, and their instruction manuals cover everything one needs to know about using them, including the necessity for replacing any cap or plug removed in the course of testing. If you are writing a method statement for people doing combustion tests, you might want to add a warning to avoid touching hot surfaces and a reminder that the business end of the probe will be hot after the test and shouldn't be touched or handled until it has cooled down. Sound like common sense? That's because it is, and this advice should not therefore be used in countries where people are legally required to be warned that coffee may be hot.

1 April 2013 (APRIL FOOL'S DAY)

A LITTLE LIGHT READING...

Got your shopping basket and cheque-book ready? Let’s build that library of energy-management systems standards!

We’ll start with ISO 50001 “Energy management systems. Requirements with guidance for use” at Ł174 (or bizzarely, Ł12 less for the laminated version), and to make sure we implement it correctly, fork out Ł212 for ISO 50004 “Energy management systems. Guidance for the implementation, maintenance and improvement of an energy management system”. To help us understand it all we might add PD CEN/CLC TR 16103 “Energy management and energy efficiency. Glossary of terms”. That’s only an extra Ł152 but we can probably pass up on ISO 9229 “Thermal insulation. Vocabulary” (Ł200) especially as the subject seems also to be covered in the cheaper ISO 9251 “Thermal insulation. Heat transfer. Conditions and properties of materials. Vocabulary” at just Ł90.

Stay with me... Next, we will almost certainly want to do some energy audits. ISO 50002:2014 ED1 “Energy audits. Requirements with guidance for use” would seem to cover the ground, and at Ł103 it’s Ł5 less than the European Standard EN 16247-1 “Energy audits. General requirements”. But – decisions, decisions - EN 16247 also boasts other sub-standards: Part 2 for buildings at Ł192; Part 3, processes at Ł146; and Part 4, transport at Ł104 (the prices differ because they charge per page). If we want to use benchmarking we could pick up a copy of EN 16231 “Energy efficiency benchmarking methodology” for only Ł152, and thinking about the qualifications of the people doing the work we should add PAS 51215 “Energy efficiency assessment. Competence of a lead energy assessor. Specification”, which at Ł70 seems quite good value until you read it.

Swap your shopping basket for a trolley now, because we’re going to think about measuring and verifying our savings. To set the scene, let’s fork out Ł212 on EN 16212 “Energy Efficiency and Savings Calculation, Top-down and Bottom-up Methods”. Please suppress the thought that probably crept into your mind on seeing the words “up” and “bottom” in the title of one of these worthy publications, especially as we will see them again when we splash out Ł146 on CWA 15693 “Saving lifetimes of energy efficiency improvement measures in bottom-up calculations”. Then to be on the safe side let's get ISO 50015 “Energy management systems. Measurement and verification of energy performance of organizations. General principles and guidance” at Ł152, plus ISO 50006 “Energy management systems. Measuring energy performance using energy baselines and energy performance indicators. General principles and guidance” (Ł174). Nearly done... To make sure that our efforts to comply with all this stuff are up to scratch, let’s round off with Ł146 for ISO 50003 “Energy management systems. Requirements for bodies providing audit and certification of energy management systems”.

All in all, the bill could be over Ł2,000. There is no truth in the rumour that the International Standards Organisation, British Standards, and the Comité Européen de Normalisation are contemplating a joint venture to be called “ISO, BS and CEN Enterprises” or ISOBSCENE.

12 March 2013

CORRECT USE OF AVERAGE DEGREE DAY FIGURES

From time to time I am asked for 20-year average degree-day figures, but from past years. A request like this always rings slight alarm bells because it is a bit like asking for a copy of a weather forecast that was broadcast a few months ago. Twenty-year averages are only supposed to be used for estimating future consumption, so only the most recent set is of any value.

It turns out that some users are using the averages for weather adjustment. They are taking the fuel used for heating in a given month, dividing by actual degree days (so far, so good) and then multiplying by the 20-year average degree days for that month. This gives them actual consumption adjusted to average weather. This is where an error creeps in. If they use a revised average each year, the result will change. Suppose the climate is getting milder: their adjusted fuel consumption will turn out less than it should, flattering the trend. To make the comparison fair one should use the same "average" degree-day number every year.

Just choosing a set of twenty-year average figures and sticking with them in perpetuity is one solution, but it isn't the best. It cures distortion of trends but it still leaves one unable to benchmark one building against another. To do that, the buildings' fuel consumptions should be normalised against a common fixed reference standard weather year, such as that shown at www.vesma.com/ddd/std-year.htm

8 February 2013

PENALTY FOR EXCESSIVELY-TIGHT ENVIRONMENTAL CONTROL

The National Library of Scotland has achieved energy savings of 34% over two years. By careful experimentation with temperature and relative humidity settings, they found they could safely operate outside the limits stipulated in BS5454, whose requirements they had previously been following rigidly. According to NLS's Linda MacMillan, speaking at the Scottish Energy and Environment Conference on Tuesday, their consumption is down becasue with floating setpoints their dehumidification load is now "almost at nil" -- with no risk to their stock.

It seems that there had been no scientific basis to the limits for temperature and RH cited in BS5454, and it was probably a case of the air-conditioning industry dominating discussion in the drafting process.

24 January 2013

OPTIMUM START CONTROL

Looking at how somebody had set the timing on a school heating system I noticed that their weekday schedule ran from 06:00 to 17:00. Normally this might be reasonable, but only if they were using a fixed-time control. In fact the control was an "optimiser", a timeswitch that automatically delays the startup time to prevent the building getting up to temperature earlier than necessary. Optimisers adapt to the characteristics of the systems they control, aiming to achieve a chosen target temperature at a specified time. Therein lay the users' error: their school was going to be snug and cosy at six o'clock every morning (at least two hours prematurely). An optimiser schedule must be set for the start of occupancy, not the plant startup time.

They had also set the optimiser target temperature at 21 degrees C. Two things wrong with that. The main thing is the risk that this target temperature will not be reached (because the normal thermostatic controls will prevent it getting there). If that happens, the optimiser will always think it has failed to allow enough preheat time, and will progressively start the plant earlier and earlier every day. The other bijou problemette with 21 C is that it is illegal. The Fuel and Electricity (Heating) (Control) (Amendment) Order 1980 generally prohibits artificial heating above 19 degrees.

2 October 2012

HOT TIP - LITERALLY

Pretty well everyone has combustion apparatus (typically the burners on heating boilers) among the things they deal with as an energy manager. Management of combustion efficiency is a universal and often-neglected opportunity to save energy for next to nothing. Here's how.

A proportion of the heat released during combustion inevitably escapes up the chimney (a) because the exhaust gases are hot, and they contain either (b) any excess air that wasn't needed for combustion or (c) unburned fuel if insufficient air was supplied. Ensuring that burners are properly tuned during routine maintenance will ensure that the proportion of energy lost in this manner is minimised. It may only save a few percent, but the point is that the saving is free if you manage your maintenance contractor proactively: good burner tuning is just part of diligent maintenance.

Interesting, percentage losses in flue gases can be inferred using measurements of their oxygen and carbon monoxide levels, together with their temperature relative to the air in the boiler room. The apparatus to do this is perfectly affordable for many energy users, enabling them to keep an eye out for loss of efficiency.

18 September 2012

ESTABLISHING ATTITUDES

One of the first steps in any energy motivation and awareness campaign is to establish what people in the organisation currently think about the subject. A questionnaire is one possible method, but designing an effective one is tricky. They quickly become bloated, and think about this: how often have you filled in a multiple-choice questionnaire and been frustrated because the answer you wanted to give was not one of the options?

I would like to suggest two guiding principles. Firstly limit yourself to four questions; and secondly make them open-ended. The four that I usually use are:

Do you think there is significant energy waste at work?
If so, whose job should it be to deal with it?
If you think it is important for the organisation to save energy, why?
What other aspects of your work are as important, or more important?

The answers to these questions are all you should need as a foundation. You may find the responses rather surprising, but that is good because it shows that your own preconceptions were wrong.

If you work for a large organisation you probably dread having to read and analyse all the free-text responses. But there is a way around that problem: invite people to discuss the questions with their friends at work and submit a group view. That not only reduces your workload, but also raises the profile of the subject, which is after all what you are trying to do.

The next step would be to publish the conclusions promptly in a half-page summary, focussing on those areas of consensus which are helpful or neutral to your campaign. This feedback serves several purposes, one of which is that it subtly helps to align everyone's attitudes through the phenomenon called 'social proof', the unconscious tendency to behave like other people whom we regard as similar to us. And of course the effect works on everyone who hears the feedback, not just those who responded to the survey.

But don't do the survey in isolation: have your next few steps planned out. Be ready, for example, to have people suddenly start making more suggestions. A positive groundswell of opinion will be wasted if your campaign cannot respond smoothly.

16 August 2012

BAD PRACTICE GUIDE: TWELVE TIPS FOR DESIGNING A REALLY AWFUL ENERGY DASHBOARD

1. Make maximum use of decoration. Bright colours, gradient fills, 3-D effects, borders and boxes (preferably with shadows) are essential because your readers have a mental age of six and are easily bored by information.

2. Put your logo prominently on the top left-hand corner of the screen, because that is prime real estate. It is where the user’s eyes will usually land first, and your brand identity is surely the most important piece of information on the screen.

3. Pack in as much data as you can. Empty space on a dashboard is a clear signal that you have not been working very, very hard.

4. Pie charts are the perfect choice for presenting comparative data because (a) there is a limit to the number of items that they can portray, and (b) the human eye finds it difficult to judge the relative areas of the segments (use 3-D pie charts to make it even harder). Labelling the segments with text around the perimeter, connected by leader lines, is an excellent way to make the graphic shrink to an unusable size, but you may prefer to use a colour-coded key which will significantly slow down interpretation of the chart — and ideally render it ambiguous or even unusable for anyone with impaired colour vision.

5. Dial gauges are a very good way to use more space than necessary to report a single numerical value. Using a dial proves that you are clever and understand the dashboard metaphor. If users need to compare a selection of different values, an array of ‘rev counter’ gauges is an attractive way to prevent them doing so easily.

6. Make liberal use of vertical text for chart labels, to make users crick their necks (having a mix of upward and downward text directions really shows your disregard for their comfort). Text must be in a mixture of large and tiny fonts: large to use up space, small to make things difficult to read, and the mixture to make the presentation uglier in case you have otherwise failed to make it garish enough.

7. When reporting two or more associated variables, stacked column graphs are an excellent way to conceal trends and comparative values. If possible put the values with most variability at the bottom of the stack, to ensure that the values of the second and subsequent tranches are as difficult as possible to follow.

8. If you are displaying a history of monthly consumption values, use a column-chart format overlaying one year on another (all Januaries together, and so on) to prevent the long-term trend being visible and to hide what happens at the turn of the year. With the right choice of column colours, moreover, you can arbitrarily emphasise one year in particular. Never use a simple line chart to portray the history of a measured value, because it makes it too easy to spot trends.

9. Always report numerical values to as many decimal places as possible.

10. A table should always be presented as a grid with lines separating the rows and columns, because the recipients, who are stupid, will not be able to read it otherwise. They may not even realise that it is a table. Redundant separators are also an excellent way to force the use of unreadbly-small type.

11. Be sure to restart all reports and charts at the beginning of the year and discard any earlier data. It is vital to avoid moving averages, rolling totals and other representations that make it easy to perceive longer-term trends. Instead, be sure to reset all averages and cumulative totals to zero each year (or on a monthly, weekly or daily basis if it is important to disrupt the continuity of shorter-term reports).

12. Avoid giving any indication of context or significance, such as whether a reported value is within acceptable limits, on a trend in a particular direction, subject to high variability, and so on. Under no circumstances should you compare actual with expected values, much less prioritise any deviations or hide instances that are not significant. Your invariable aim, when reporting a numerical value, should be to have the user say: “so what?”.

... Joking aside, if you are interested in how to do the job well, I heartily recommend the textbook 'Information Dashboard Design' by Stephen Few, who is a strong advocate of clean, lean and uncluttered displays and offers a wealth of design tips.

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