Compressed Air Solutions founder and editor, Byron Raal, explains why it's time to get serious about compressor heat recovery.
Walk into almost any manufacturing plant and the hottest room on site is not the boiler room. It is the compressor room. And in most facilities the mechanical services design treats it as a ventilation problem: duct the heat outside, keep the room under temperature, job done.
That is a waste stream hiding in plain sight. Between 80 and 90 per cent of the electricity a compressor draws leaves it as heat. A 90 kW compressor running two shifts is a 70 kW heater running two shifts. Plenty of sites pay to make that heat, pay again to reject it, then pay a third time to heat water and space with gas a few metres away.
Recovering it is a mechanical services job, not a compressor vendor add-on. Ducted air-to-air recovery handles space heating in the southern states. Hydronic recovery feeds wash-down water, amenities hot water or boiler feed wherever there is process demand. The kit is simple and proven. The barrier is scope: compressed air usually sits outside the mechanical package, so nobody draws the connection.
The parallels with your world run deeper than heat. Compressed air behaves exactly like the HVAC systems this industry designs. It gets sized for a peak that rarely arrives, then runs flat out against a partial load. A variable speed drive on the right compressor does what a VSD does on a chiller, and on the right load profile it returns 15 to 30 per cent of the energy bill.
And it leaks like bad ductwork. An unmanaged compressed air system loses 20 to 30 per cent of everything it produces through leaks. No engineer would accept a chilled water loop dumping a quarter of its capacity before it reaches the load. In compressed air, that is a normal Tuesday.
There is an emissions line here too. At the 2025 National Greenhouse Accounts national grid factor of 0.62 kg CO2-e per kilowatt hour, a recovered 70 kW of compressor heat displacing gas, or a 20 per cent leak reduction on a large system, is real Scope 2 and Scope 1 abatement, measurable with nothing more exotic than a data logger.
So here is the opinion: if you are scoping an energy assessment or a mechanical upgrade in an industrial building and the compressed air plant is not in your thermal model, the single easiest heat recovery and demand reduction on the site is being left on the table.
Put the compressor room inside the mechanical scope. Your client is already paying for that heat. They may as well use it.
About the author
Byron Raal is the founder and editor of Compressed Air Solutions, an independent, vendor-neutral reference on compressed air for Australian industry.