Marion is a senior energy auditor with Maxaura Ltd
Air is free – until its compressed, then it becomes one of the most expensive resources on site. However, many users pay it scant attention so long as it supplies processes consistently. This is not wholly surprising - the cost of compressed air is as invisible as the utility itself, remaining comfortably hidden in the electricity bill and as such, unaccountable. The old maxim “If you don’t measure it you can’t manage it” holds as true for compressed air as any other resource.
Before implementing any improvements to a compressed air system, you should establish your current costs and consumption by way of an audit. An audit is necessary to establish a baseline against which improvements can be measured.
To justify an audit it is helpful to estimate the cost of running the compressors, users may estimate it thus:
Annual energy cost = motor power (kW) x % utilisation x operating hours x unit cost electricity (£ per kWh)
e.g for a 75kW compressor running 24/7 at 70% utilisation, 8p/kWh the annual energy cost is:
75 x 0.70 x 8,760 x 0.08 = £36,792
This figure whilst only as estimate may surprise some users and prompt further investigation. Note: this is only the energy cost of the compressor. The electrical consumption of dryers will be additional to this figure, as will servicing costs etc. and capital depreciation.
For establishing the baseline consumption, there are a couple of options:
Useful linksBCAS is the trade association representing manufacturers, distributors and users of compressed air and vacuum equipment and services. It acts as a one-stop shop for all compressed air related matters such as technical, legislation, health and safety and energy efficiency. Follow these links for: compressed air training courses and posters on energy saving in compressed air
If you found this page in isolation through a search engine, you might want to check out other free advice from the Energy Management Register