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Dairy and food processing

What is Coefficient of performance (COP)?

Definition

Coefficient of performance (COP) is the ratio of useful heating or cooling a system delivers to the energy it consumes, with both in the same units. A chiller that removes three kilowatts of heat for every kilowatt of electricity has a COP of 3. Higher COP means less energy for the same duty.

What it is

COP is a dimensionless efficiency ratio for refrigeration plants, chillers, heat pumps and air conditioners. For cooling, it is heat removed divided by work input. For heating, it is heat delivered divided by work input.

COP is not fixed. It changes with load, condensing temperature, evaporating temperature and the condition of heat exchangers. A plant with dirty condensers or a poorly staged compressor set will show a falling COP even when nothing has visibly failed.

Rated COP comes from test conditions. Operating COP, measured on site, is what matters for the energy bill, and it should include auxiliaries such as pumps and fans when comparing systems.

Who it applies to / where it is used

COP is used by refrigeration engineers in dairies and food plants, chiller plant operators in airports, hospitals and campuses, and anyone specifying heat pumps. Related measures include EER, IPLV and kW per TR.

How it is measured / what evidence it needs

Operating COP needs a measured cooling or heating output and a measured energy input over the same period.

  • Cooling or heating output from flow and temperature difference
  • Electrical input to compressors and, separately, to pumps and fans
  • Condensing and evaporating conditions
  • Load and ambient conditions for fair comparison
  • COP trend by machine and by plant

How Aqueduct helps

Aqueduct calculates operating COP from live meter data and compares it with the plant's own baseline.

  • aQ EnergySmart reports COP and kW per TR per plant and machine
  • aQ PredictIQ flags a falling COP that points to fouling, refrigerant or staging issues
  • Fixes are routed into the customer's CMMS with the measurements attached
  • After a fix, the meter verifies whether COP recovered
Questions

Coefficient of performance (COP): common questions

It depends on the chiller type, load and conditions, so compare against the manufacturer's rating and your own baseline under similar conditions. A falling COP over time is the clearest sign something needs attention.

COP is cooling out divided by energy in, in the same units, so higher is better. kW per TR is electrical input per ton of cooling, so lower is better. They describe the same efficiency from opposite directions.

Equipment ratings often cover only the compressor. For a fair site comparison, measure system COP including pumps, fans and cooling towers.

Higher outdoor temperatures raise condensing pressure, so compressors work harder for the same cooling. Weather normalization separates this effect from real performance loss.

See Aqueduct on your own facility.

Bring a site, a utility bill or a question. We will show you where the loss is.

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