SCOP or COP? Master the key power comparison terminology!

The heating industry employs numerous technical terms and abbreviations that may confuse ground source heat pump owners. This guide explains key efficiency concepts.

Energy Requirement

Kilowatt-hours consumed annually to heat a house and provide domestic water. In a detached house, the typical distribution might be: heating 52%, domestic electricity 28%, domestic hot water 20%. Ground source heated homes typically allocate 60% of energy to heating and hot water production, with domestic electricity comprising the remainder.

Ground Source Heat Pump Energy Requirement

The maximum kilowatts required to heat the building and domestic water on the year’s coldest day.

Ground Source Heat Pump Nominal Power

The electricity power drawn from the mains under nominal conditions. For example, Gebwell Aries 6 inverter model (0°/35°) has nominal input power of 0.78 kW, while the Aries 12 model has 1.36 kW. The notation (0°/35°) indicates conditions where the brine circuit temperature is 0°C and the heat pump delivers 35°C water to the heating circuit.

Heating Output

Measured according to either partial or full power capacity relative to building requirements.

Partial-Power Heat Pump

Has sufficient capacity for reasonably cold weather; internal heating resistors supplement output during extreme cold, increasing overall electrical energy requirements and potentially reducing drilling depth.

Full-Power Heat Pump

Delivers sufficient capacity to heat a property even in extreme conditions without requiring additional heating resistors.

SFS-EN 14511

Published by Suomen Standardoimisliitto, this standard establishes principles for calculating energy requirements of heating and cooling heat pumps. The Coefficient of Performance (COP) is calculated according to this standard.

Coefficient Of Performance (COP)

The “heat coefficient” represents “efficiency”—the ratio of consumed to produced energy. For heat pumps, it shows how effectively electrical energy converts to heat energy.

Formula: Heat energy produced (kW) ÷ Electrical energy consumed (kW) = COP

A COP of 5 indicates that 1 kW of input produces 5 kW of heat. Higher values indicate greater efficiency.

COP measurements are conducted at +7°C, which may not reliably indicate performance in sub-zero temperatures. The older SFS-EN 255 standard yields higher COP values than SFS-EN 14511 calculations. The Gebwell Aries inverter heat pump’s COP (0°/35°) is 4.8.

Seasonal Coefficient of Performance (SCOP)

SCOP provides clearer efficiency indication than COP by accounting for variations across different heating periods. It incorporates seasonal temperature intervals, basic temperature measurements, dimensioning loads, and geographical climate zones. Northern European calculations use Helsinki climate conditions as the baseline.

The Gebwell Aries 6 inverter (0°/35°) has SCOP value of 5.6, while the Aries 12 achieves 5.8.

SCOP vs. COP

“SCOP is a more reliable indicator when comparing the efficiencies of heating devices.” It provides realistic efficiency assessment across varying heating periods, enabling easier comparison between manufacturers’ models.