Coefficient of Performance (COP): How It’s Measured and Used

Source: https://www.idm-energie.at/en/heat-pump-efficiency/cop/

        Coefficient of Performance (COP)Waqar Khan2026-07-06T14:58:31+02:00
            Home » Heat Pump Efficiency » Coefficient of Performance (COP)Coefficient of Performance (COP) in Heat Pump EfficiencyCOP is one of the most common ways to describe how efficiently a heat pump is running at a specific moment. If you are comparing heat pumps or trying to understand a datasheet, COP is usually the first efficiency number you will see.

It matters because heat pumps do not “create” heat from fuel. They move heat from a source (air, ground, or water) into your building. When conditions are favorable, the delivered heat can be several times higher than the electrical power the heat pump consumes.
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What COP meansWhat COP tells you (and what it does not)Why COP changes so muchHow COP is tested and written on datasheetsWhat is a “good” COP?COP vs SCOP vs SPF (quick clarity)What can lower COP in the real worldHow to use COP correctly when comparing heat pumpsPractical takeaway for homeowners and early researchFrequently Asked Questions (FAQs)What COP means
COP (Coefficient of Performance) is the ratio of:

useful heat delivered (heating output)
divided by electricity consumed (input power)

In simple form:
COP = Heat output / Electric input
So if a heat pump delivers 4 kW of heat while using 1 kW of electricity, the COP is 4.0.
This is the same core definition used in standard rating methods for heat pumps.
What COP tells you (and what it does not)
COP is good for

understanding instant efficiency at a defined operating point
comparing models when the test conditions are identical
seeing how much efficiency changes with temperature lift (difference between source temperature and heating water temperature)

COP is not good for

predicting year-round performance
estimating real annual electricity cost by itself

Because COP is measured at a specific condition, it can look great on paper but still differ from your building’s real operating conditions. Real-world performance often differs from lab ratings due to installation, controls, and climate.
If you want a year-round metric, use SCOP or SPF.
Why COP changes so much
COP is mainly driven by the temperature difference the heat pump must “lift”:

warmer heat source (e.g., mild outdoor air, stable ground loop) → higher COP
lower required flow temperature (e.g., floor heating) → higher COP
colder outdoor air + higher flow temperature (e.g., older radiators) → lower COP

This relationship is widely recognized in heat pump performance literature and field analysis.
How COP is tested and written on datasheets
Manufacturers usually publish COP using standardized test methods. In Europe, COP performance testing is typically done using EN 14511, which defines rating terms and test conditions for heat pumps and similar equipment.
Typical notation you will see: A7/W35 (example)
This describes the test condition:

A7 = air source temperature 7°C (for air-source units)
W35 = heating water supply (or outlet) temperature 35°C

So A7/W35 COP is the COP measured at those conditions.
EN 14511 also uses multiple temperature levels / water outlet temperatures to represent different applications (for example low-temperature heating).
Important: COP numbers are only comparable when the same standard and the same test point are used.
What is a “good” COP?
There is no single “good COP” without context, because the test point matters.
That said, for household heating applications, a COP in the range of about 3–4 is commonly referenced under many typical operating conditions (and it will be higher in mild conditions, lower in cold weather or high flow temperatures).
A more useful way to think about it is:

Low-temperature heating systems (e.g., floor heating) tend to enable higher COP
Higher-temperature heating systems require more lift and tend to reduce COP
Air-source COP drops in colder weather and can be impacted by defrost cycles near freezing
Ground-source systems often keep steadier source temperatures, which can stabilize efficiency (your SCOP/SPF pages are the right place to quantify this across the season)

COP vs SCOP vs SPF (quick clarity)
People mix these up, so here is the clean separation:

COP = instantaneous efficiency at one defined condition (lab rating point)
SCOP = seasonal efficiency calculated across part-load conditions and climate profiles (EU seasonal method)
SPF = measured seasonal efficiency in real operation (from metering/monitoring), often used for system-level validation

What can lower COP in the real world
Even if the unit has a strong datasheet COP, system design and operation can reduce it:

flow temperature set too high (common efficiency killer)
poor hydraulic balance, wrong pump settings, or unnecessary buffer/volume flow issues
frequent on/off cycling (especially at part load)
defrost operation (air-source systems around freezing)
controls not tuned to the building and emitter type

How to use COP correctly when comparing heat pumps
Use this checklist:

Match the test point (example: A7/W35 vs A2/W35 are not the same)
Match the standard (e.g., EN 14511 for rated points in Europe)
Check the application temperature (35°C vs 55°C water makes a major difference)
Don’t compare COP across different heat sources without noting the source conditions (air vs brine vs water)
For buying decisions, confirm seasonal metrics (SCOP) and system design fit (emitters, flow temperature, controls)

Practical takeaway for homeowners and early research
COP answers one simple question:
“How efficiently does the heat pump convert electricity into heat at this exact condition?”
For a realistic expectation of bills and comfort, COP should be treated as a starting point, and then supported by:

seasonal metrics (SCOP/SPF)
flow temperature design
heat emitter suitability
monitoring/metering once installed

Configure your personalized heat pump system!Plan your heat pump system with iDM Energiesysteme. Discover efficient heating, cooling, and hot water solutions for new buildings, renovations, and modern energy systems. Configure and personalize your iDM heat pump solution in just a few clicks.

CONNECT WITH OUR EXPERTS
50+ Years of Heat Pumps Experience
Frequently Asked Questions (FAQs)

What is the coefficient of performance of a heat pump?
The coefficient of performance (COP) of a heat pump is the ratio between the heat it delivers and the electricity it consumes at a defined operating condition.
For example, if a heat pump supplies 4 kW of heat while using 1 kW of electricity, its COP is 4.0. This means it delivers four units of heat for every one unit of electrical energy used.
COP describes instantaneous efficiency at a specific test point, not year-round performance.
What does coefficient of performance (COP) mean?
COP expresses how effectively a heat pump converts electrical energy into useful heating output at a given moment.
Unlike combustion systems, a heat pump transfers existing environmental heat. Because of this transfer process, the useful heat output can be several times higher than the electricity input. That is why COP values are often greater than 1.
How is heat pump COP calculated?
COP is calculated using a simple ratio:
COP = Heat Output ÷ Electrical Input
Where:

Heat output is measured in kilowatts (kW)

Electrical input is measured in kilowatts (kW)

The result has no unit because it is a ratio.
Manufacturers determine COP under standardized laboratory conditions, typically according to EN 14511, which defines how heat pump performance must be tested and reported in Europe.

Is a higher COP better?
Yes, under the same test conditions, a higher COP means the heat pump produces more heat per unit of electricity consumed.
However, COP values can only be compared if:

The same test standard is used

The same source temperature is used

The same heating water temperature is used

A COP measured at mild outdoor conditions will naturally be higher than one measured in cold conditions.

What is considered a good COP for a heat pump?
There is no universal “good” COP without context, because the test condition strongly influences the result.
For many residential heating applications at moderate source temperatures and low flow temperatures, COP values around 3 to 4 are common. In milder conditions or with low-temperature systems such as floor heating, COP can be higher. In colder conditions or high flow temperature systems, it will be lower.
The more important factor for homeowners is seasonal performance (such as SCOP), not a single test-point COP value.
Can COP be greater than 1?
Yes. In fact, it is normal for heat pumps.
COP can be greater than 1 because a heat pump moves heat from the environment instead of generating it directly from electricity. The electrical energy is mainly used to operate the compressor and system components, while most of the delivered heat comes from air, ground, or water.
Why can COP be greater than 1?
COP can exceed 1 because it measures heat moved, not energy created.
If a heat pump uses 1 kW of electricity and extracts 3 kW of environmental heat, it can deliver around 4 kW of total heating output. The ratio (4 ÷ 1) equals 4.0.
This does not violate energy conservation. The system is transferring heat from the environment and upgrading its temperature level.
Is COP the same as efficiency?
No. COP is not the same as traditional efficiency.
Conventional heating efficiency (such as a gas boiler) compares output heat to fuel input and is expressed as a percentage, typically below or close to 100%.
COP is a performance ratio for heat transfer systems and can be higher than 1 because it includes environmental heat energy in the output.
For annual evaluation, seasonal metrics such as SCOP or real measured system performance are more suitable than a single COP value.

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