You don't need a consultant to find the big waste in a compressed air system. You need your electricity bill, a pressure gauge, a stopwatch, and a quiet evening. This page walks through a self-assessment that finds the large items in most systems.

If your system is large (multiple big compressors, complex demand), a professional audit with proper data logging is worth it — but do this first anyway. You'll buy the audit better informed.

Step 1: Know what your air costs

Estimate the yearly electricity cost of your compressed air: compressor power × loaded hours × your tariff. If you don't meter the compressor separately, nameplate kW and a realistic estimate of running hours gets you close enough to start.

Write that number down. Every percentage in the steps below is a percentage of it. (More on the real cost per m³: The Cost of Compressed Air.)

Step 2: Map the pressure

Measure pressure in the compressor room and at the farthest / most critical points of use, during production.

  • The difference is your pressure drop. More than 0.5–1 bar means the distribution system is costing you real money.
  • Then ask: what does the most demanding machine actually require (check the manual)? If the compressor setpoint is more than pressure-drop-plus-a-small-margin above that, the setpoint is too high. Rule of thumb: every 0.1 bar costs ~0.7% in energy.

Step 3: Measure your leak rate

The shutdown test — the single most valuable measurement you can do yourself:

  1. Pick a time with no production (evening, weekend).
  2. Let the compressor pump the system to its unload pressure, with all machines connected but idle.
  3. Watch the compressor: with zero legitimate consumption, every second it runs loaded is feeding leaks.
  4. Time it over several load/unload cycles: loaded time ÷ total time = leak rate as a fraction of compressor capacity.

A compressor that runs loaded 15 minutes out of every hour on a dead-quiet system is losing ~25% of its capacity to leaks. Under 10% is good; 20–30% is normal for unmanaged systems and worth fixing immediately. How to find the leaks once you've measured them.

Step 4: Watch the compressor work

Spend 30 minutes in the compressor room during normal production:

  • Load/unload pattern: how long loaded, how long unloaded? A fixed-speed compressor running unloaded still draws roughly 20–30% of full-load power for zero air. Lots of short cycles or long unloaded stretches → see Unload Running Explained and check your receiver size.
  • Multiple compressors: are two or three all running part-loaded where one loaded plus one trim would do? That's a sequencing problem — often the biggest finding in multi-compressor plants.
  • Night and weekend running: if a compressor runs outside production hours, ask what it's feeding. The honest answer is usually "the leaks."

Step 5: Put numbers on it and prioritize

For each finding, estimate the yearly cost with the rules of thumb above — leak rate × capacity share, 0.7% per 0.1 bar, unload hours × ~25% of rated power. Rough is fine; you're ranking, not invoicing.

Typical priority order, by payback:

  1. Setpoint reduction — free, immediate.
  2. Leak repair — parts and a few hours of labour; pays back in weeks. Then make the shutdown test a monthly routine, because leak rates grow back.
  3. Shutting off air outside production (valves, timers) — cheap, immediate.
  4. Control and storage improvements — receiver, sequencing, pressure band.
  5. Distribution fixes (filters, pipe sizing) — real money, longer payback.

Most plants that do this honestly find 15–30% of their compressed air cost is avoidable — measured, not promised.