SCOP or COP? Master the key power comparison terminology!

Do you know the difference between SCOP and COP efficiencies? The jargon used by heating industry professionals is rife with terms and abbreviations. Check out the key terms to know what we’re talking about!

Do you know the difference between SCOP and COP efficiencies? The jargon used by heating professionals is rife with terms and abbreviations that may not be instantly obvious to a normal ground source heat pump owner. Take a look at the key concepts of the field to make sense of the heating system efficiency comparisons.

Energy requirement

The kilowatt-hours (kWh) used in a year to heat a house and domestic water. The energy requirement includes the total electricity consumed by all of the electrical appliances in the house.

The indicative energy requirement distribution of a detached house could be, for example: heating 52%, domestic electricity 28%, domestic hot water 20%. In a ground source heated detached house, the production of heating and domestic hot water typically takes up 60% of the energy, and the domestic electricity takes up the rest.

Ground source heat pump energy requirement

The energy requirement is the maximum of kilowatts required to heat the building and domestic water on the coldest day of the year.

Ground source heat pump nominal power

The power (kW) of the electricity used by a ground source heat pump drawn from the mains in the nominal conditions. For example, the nominal input power of a Gebwell Aries 6 inverter ground source heat pump (0°/35°) is 0.78 and the nominal input power of an Aries 12 ground source heat pump (0°/35°) is 1.36.

(0°/35°) means the input powers in the examples were calculated in conditions where the temperature of the heat source, i.e. the brine circuit, is 0 degrees and the heat pump sends water in 35 degrees to the heating circuit..

Heating output of the ground source heat pump

The ground source heat pump’s heating output is measures according to the building’s heating requirements either as partial or full power.

Partial-power ground source heat pump

A partial-power heat pump has enough capacity to heat the house at reasonably cold weather. In extreme cold, the pump’s internal heating resistors produce the extra heat required. When acquiring a partial-power ground source heat pump, the amount of the required electrical energy increases, which slightly reduces the depth of the energy well. When getting a heating system, it is a good idea to investigate the effects of the ground source heat pump measurements on the total costs.

Full-power ground source heat pump

A heat pump that is measured at full power has enough power to heat a property even in extreme cold without having to produce the extra heat using heating resistors.

SFS-EN 14511

Published by Suomen Standardoimisliitto, the SFS-EN 14511 standard sets the principles according to which the energy calculation of heat pumps intended for heating or cooling room spaces is made. The coefficient of performance, or COP, of heating devices is calculated in accordance with this standard.

Coefficient Of Performance (COP)

The COP rating, i.e. the heat pump’s heat coefficient is usually referred to as ‘efficiency’. COP indicated the ratio of the consumed and produced energy. The COP of an air source heat pump indicates how efficiency the consumed electrical energy can be converted into heat energy.


The heat energy received from a ground source heat pump (kW)/the electrical energy consumed by a ground source heat pump (kW) = COP

For example, COP 5 means that a 1 kW input power produces 5 kW of heat energy. The higher the figure, the more energy-efficient the device is.

You can reach the COP rating by conducting the measurements at a temperature of +7 degrees. Because of this, COP alone will not always yield reliable information about the functionality of a heating device, for example, in sub-zero temperatures. When comparing COP ratings, it is a good idea to confirm the standard and conditions used in the calculation. The previously used SFS-EN 255 standard gives a better COP value than calculations performed using the official SFS-EN 14511 standard.

For example, the Gebwell Aries inverter ground source heat pump’s COP (0°/35°) is 4.8.

Seasonal Coefficient of Performance (SCOP)

SCOP, or the Seasonal Coefficient of Performance, provides a clearer indication of the efficiency of the ground source heat pump than COP because it takes into account variations between the different heating periods.

SCOP is calculated for four different heating periods because the temperature intervals applied to the calculation, the basic temperature measurements and the dimensioning loads are seasonal. In addition, geographical climate zones are taken into account when calculating the heat coefficients of ground source heat pumps. In northern Europe, the calculation of a heating period heat coefficient is based on the climate conditions of Helsinki.

For example, the Gebwell Aries 6 inverter ground source heat pump (0°/35°) has a SCOP value of is 5.6. The corresponding SCOP value of the Aries 12 ground source heat pump is 5.8.


Of these two efficiency figures, SCOP is a more reliable indicator when comparing the efficiencies of heating devices. SCOP provides a more realistic idea of the efficiency based on varying heating period, which makes it easier to compare the ground source heat pumps of different manufacturers or the different models of the same manufacturer.

Read more about our extensive ground source heat terminology here »