2. What is the coefficient of performance (COP) of an air source heat pump?
Air Source Heat Pumps

What is the coefficient of performance (COP) of an air source heat pump?

An air source heat pump’s COP is the ratio of useful heating provided to the energy consumed. 

Along with seasonal coefficient of performance (SCOP), COP is a critical measure, offering insights into how efficiently an ASHP operates. 

 

Read on to learn more about: 

 

  • How COP is calculated
  • The difference between COP and SCOP
  • Why COP is important for you as the homeowner
  • What can affect COP and SCOP
  • Ways to maximise COP and SCOP 
Advantages and Disadvantages of ASHPs 2

Calculating COP: the formula for efficiency

Calculating (COP) is worked out by using the following formula: COP = Heat Output (in kW) / Electrical Input (in kW). 

 

This calculation helps determine how efficiently a system like a heat pump converts electrical energy into heat under certain operating conditions. For example, the performance that is achieved when the heat pump runs at 45°C when the outside temperature is 2°C.

 

There is no set limit for COP ratings, however the higher the score, the greater the efficiency of the heat pump. For instance, if a heat pump’s COP rating is 3, this means that it provides three units of heating for every unit of electricity consumed.

COP is calculated using the following formula: Heat Output (kW) / Electrical Input (kW).  

The difference between COP and SCOP   

While the COP rating offers a snapshot of efficiency under specific conditions, the Seasonal Coefficient of Performance (SCOP) provides a more realistic view of how efficient your heat pump will be during the course of the year by accounting for seasonal variations. This approach helps you make an informed decision as to whether your heat pump will deliver the efficient performance that you expect.

 

SCOP is calculated under certain conditions as defined by the EN 14825 standard, following this formula: Total Seasonal Heat Output (kWh) / Total Seasonal Electrical Energy Input (kWh). 

 

In other words, whilst COP and SCOP are both similar and important metrics, the former provides a snapshot of your heat pump’s expected efficiency, whereas SCOP looks at a season overall.

SCOP is calculated using the following formula: Total Seasonal Heat Output (kWh) / Total Seasonal Electrical Energy Input (kWh). 

Why SCOP and COP are important for homeowners

 

A higher rating for both COP and SCOP can, over time, lead to energy savings and reduce your environmental impact. While COP is an important indicator for choosing the most efficient air source heat pump based on your needs, for a true, accurate reflection of your ASHP’s efficiency, the SCOP value may hold greater weight particularly when looking at how efficient it will be in real-life operations. 

 

What can affect COP and SCOP?

 

The COP and SCOP ratings of a heat pump vary based on several factors. One of the most significant is the difference between inside and outside temperature. 

 
When the temperature outside drops, the heat pump will naturally need to work harder to extract warmth from the air to deliver the comfortable indoor temperature that you expect from it. That said, even with lower temperatures, a heat pump is often still more efficient than a traditional boiler, achieving between 300% and 400% greater efficiency  in many cases even in colder conditions.  


The way the heat pump is designed and installed is another, equally significant factor. Correctly installed heat pumps will have been sized and designed specifically for the property and its characteristics, taking into account heat loss calculations, insulation, and typical heating demand.

 

Maximising a heat pump’s SCOP 

 

Air source heat pumps are designed to be highly efficient when installed correctly. There are some simple steps you can also take as a homeowner to help improve your unit’s SCOP and COP ratings for maximum efficiency:

 

  • Ensure your home is properly insulated
  • Use smart thermostats and ‘setback’ temperatures to maintain a constant level of comfort
  • Upgrade your heating system to include larger radiators or underfloor heating. These work effectively with the lower flow temperatures that a heat pump operates at
  • Only heat the areas of the home you need and make use of Thermostatic Radiator Valves (TRVs) to get a constant temperature throughout your property      


Finally, a well-maintained heat pump system keeps all components working correctly and in the most efficient way. Checking refrigerant levels, clearing obstructions, and cleaning coils and filters are also key for maintaining a heat pump’s overall efficiency and ultimately, may lead to energy savings and long-term cost-effectiveness.

Baxi Heat Pumps

Our Air Source Heat Pumps will deliver reliable, energy-efficient performance. Suitable for a wide range of properties.

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