Heat pump COP, SCOP and heating season cost
Turn a SCOP off the product fiche into the electricity a heating season takes and what it costs, and set that against a boiler burning fuel.
Cost of the season
1,152
Electricity for the season
3,840 kWh
SCOP is measured over the European reference heating season under average climate conditions — the temperatures of Strasbourg — and covers space heating only. Hot water, a colder region and a warmer flow temperature all push the real figure below the one on the fiche.
Cost per kWh of heat
0.096
Seasonal space heating efficiency
125 %
SCOP ÷ 2.5, before the corrections the regulation makes for temperature controls and ground water pumps. The label figure is the corrected one, so it will not match exactly.
electricity = heat ÷ SCOP · cost = electricity × price · ηs = SCOP ÷ 2.5
A heat pump does not make heat, it moves it, which is why one kilowatt hour of electricity can land three or four kilowatt hours of heat in a radiator. How many depends on the day: the colder it is outside and the hotter the water has to leave the machine, the harder the same pump works. That is the difference between the two numbers on a product fiche. COP is one measurement at one set of conditions — the Ecodesign rules test outdoor air at +7 °C — while SCOP averages a whole heating season of them, and SCOP is the one worth putting into a bill. This page takes the heat your house needs over a winter, the SCOP of the machine you are looking at and the price on your own electricity bill, and can set the answer against a boiler burning fuel at a stated efficiency.
How it is calculated
electricity = heat ÷ SCOP · cost = electricity × price · ηs = SCOP ÷ 2.5
The Ecodesign regulation defines SCOP as the reference annual heating demand divided by the annual energy consumption, so turning it around gives the electricity a season takes: heat divided by SCOP. Multiply by your price and the season has a cost; divide the price by SCOP instead and you get what one kilowatt hour of heat costs, which is the figure that compares cleanly with a fuel. The percentage on the energy label is a third view of the same number — seasonal space heating energy efficiency is SCOP divided by the conversion coefficient CC, which the regulation fixes at 2.5, then corrected for controls and pumps.
Questions people ask
- What is the difference between COP and SCOP?
- COP is a single operating point. The regulation measures the rated COP at standard rating conditions: outdoor air at +7 °C dry bulb, water leaving at +55 °C, or +35 °C for a low-temperature heat pump. SCOP is the seasonal figure, defined as the reference annual heating demand divided by the annual energy consumption, worked out across a whole set of outdoor temperatures weighted by how many hours each one lasts. A pump quoted at COP 5 and SCOP 3.5 is not contradicting itself: the first is a mild day, the second is the winter.
- Whose winter is the SCOP measured in?
- Strasbourg's. The regulation defines average climate conditions as "the temperature conditions characteristic for the city of Strasbourg", and the reference heating season under those conditions runs to 4 910 bin hours with 2 066 equivalent hours at the design load, from a reference design temperature of −10 °C. Manufacturers may also declare colder and warmer seasons. If your winters are harder than Alsace's, the fiche number is optimistic for you, and that is a property of the test rather than a fault in the machine.
- What does SCOP not include?
- Domestic hot water, for one: space heating and water heating are rated separately, and a pump that heats a cylinder to 55 °C all summer will use electricity this page never sees. It also assumes the flow temperature of the test rather than of your radiators — an old system asked for 55 °C water will not reach the SCOP quoted for a 35 °C underfloor loop — and it says nothing about the immersion heater that takes over on the coldest days, which the regulation calls the supplementary heater.
- Why is the default SCOP 3.125?
- Because it is a floor rather than a guess. Since 26 September 2017 the Ecodesign rules have required seasonal space heating energy efficiency of at least 110 % for heat pumps and 125 % for low-temperature heat pumps, and with CC at 2.5 those are SCOP 2.75 and 3.125. Anything sold new in the EU clears one of them, so the default is the worst a legal low-temperature machine can be. Replace it with the figure on the fiche of the model you are actually buying.
- How do I compare this against a gas boiler?
- Turn on the comparison and give it two things: the efficiency the boiler runs at and the price of the fuel per kilowatt hour of fuel, not per cubic metre. Gas bills usually print both. Ecodesign has required at least 86 % seasonal efficiency from new fuel boilers since 2015, which is where the default comes from, though a boiler kept at a high flow temperature will not condense and will do worse than its rating. The comparison is running cost only — it says nothing about what either machine costs to install.
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