COP is a single test point, measured on a bench at one air temperature and one water regime. SCOP aggregates a whole heating season, part load, defrost cycles and backup heat included. Neither ever stands in for the other. And on a grant application it is SCOP, not COP, that is checked: an air source or ground source heat pump has to reach a seasonal coefficient of performance of at least 2.8 to qualify for the Boiler Upgrade Scheme, the installer business has to be MCS certified for the technology, and the Product Eligibility List does not carry the SCOP figure, so the installer calculates and evidences it.
Understanding COP and SCOP to speak the same language on site
COP: what the coefficient of performance measures under nominal conditions
The COP is a snapshot measured on a test bench, at one specific operating point (outdoor temperature and flow water temperature). It expresses the ratio of heat produced to electricity consumed. Useful for comparing two models of the same range, but out of context on a job site.
SCOP: seasonal performance, closer to real-world use
The SCOP (a European standard) aggregates several load points over a heating season, across climate profiles. It captures cycling, defrosting and shoulder seasons better. For a heat pump, it's a more meaningful benchmark for annual consumption.
Why COP and SCOP don't tell the client the same thing
A high COP can be reassuring, but it doesn't say how the machine holds up when it's cold, nor the effect of poor sizing or unsuitable emitters. The SCOP helps talk budget and usage, while reminding everyone that final efficiency depends on the installation and its settings.
Reading a datasheet and an energy label without getting caught out
Where to find COP, SCOP and test temperatures on manufacturer documents
| Technology | Minimum SCOP for the Boiler Upgrade Scheme | Where it is evidenced |
|---|---|---|
| Air source heat pump | 2.8 | installer calculation, not the Product Eligibility List |
| Ground or water source heat pump | 2.8 | installer calculation, not the Product Eligibility List |
| Air-to-air heat pump | scheme rules restrict it to residential property | MCS certification for the technology |
The Product Eligibility List confirms the model meets MCS standards, nothing more. Listing a product is not evidence that the installed system clears the SCOP floor, and Ofgem places that responsibility on the installer.
On a product sheet, look for the "performance" or "test conditions" table. You'll find the COP (at one test point) and the SCOP (over the season), sometimes alongside the ETAS expressed in primary energy. Temperatures are noted as A7/W35, with the standard reference and the calculation climate zone on the energy label, where cooling mode reads the same way through SEER and its regulated classes. Those figures also sit in catalogues built with the manufacturers, where ETAS, COP and outputs are checked reference by reference.
Points to check: A7/W35, A2/W35, A-7/W35 and what changes
A7/W35 means outdoor air at 7°C and heating water at 35°C. The further down you go toward A2 then A-7, the more efficiency drops and available output can fall. Also check the output delivered at A-7/W35 and whether an electric backup is included in the figure. This is where a lot of quotes "warm up" on paper.
Air-to-water, air-to-air heat pumps: compare on equal terms to judge performance
For an air-to-water heat pump, compare SCOPs at the same regime (35°C or 55°C) and the same zone (average, cold). For an air-to-air unit, look at the heating SCOP and the corresponding test points. Without that common ground, an A+++ rating can hide a skewed comparison. To go further on choosing between the two technologies, see choosing between an air-to-air and an air-to-water heat pump.
What makes a heat pump's performance vary in the field
Outdoor temperature, water regime (35/45/55°C) and the direct impact on COP/SCOP
The colder it gets outside, the harder the heat pump has to work to capture calories. And the higher the hot water temperature you demand, the more the COP drops. At 35°C (underfloor heating), the machine works "easily." At 45°C, it's a good compromise. At 55°C (high-temperature radiators), performance falls, and the seasonal SCOP follows the same slope.
Sizing, weather compensation curve, balancing: the settings that win points
Good sizing avoids overheating followed by constant cutoffs. Set a weather compensation curve matched to the home, aiming for the lowest possible water temperature at the right time. Clean hydraulic balancing, with consistent flow rates and properly vented emitters, stabilises operation and limits comfort swings.
Defrosting, short cycling, backup heat: the usual causes of a performance drop
On an air-to-water heat pump, defrost cycles in cold, humid air consume energy without heating the house. Short cycling increases losses and wears out the compressor. Finally, electric or boiler backup kicks in quickly if the bivalent point is poorly set or the need is too high.
Translating COP/SCOP into consumption and a bill: a simple method for your quotes
From useful output to electrical kWh: quick calculation and a worked example
For a heat pump, keep one simple rule in mind. Electrical kWh = useful kWh required by the home ÷ SCOP (or COP if you're at a specific operating point). Worked example: an estimated heating need of 8,000 useful kWh/year, SCOP 3.2. Electricity consumption ≈ 2,500 kWh/year. Then multiply by the unit rate on the customer's own bill, tariff and standing charge separated: it is the only figure that stands up if the saving is later challenged.
Factoring in DHW and heating: avoid overstating the advertised performance
Don't mix everything together. The published SCOP often covers heating only, at a given flow temperature. DHW demands higher temperatures, so a lower COP and more cycling. Do two separate lines. Heating = heating need ÷ heating SCOP. DHW = DHW need ÷ DHW COP (or tank performance). Add them up to get a credible total consumption.
Presenting a reliable order of magnitude to the client without oversimplifying the heat pump
Give a range. Take a "quote" SCOP 10 to 20% lower to cover defrosting, circulators, settings and backup heat. Present the calculation, then a low and a high scenario. Transparency and consistency beat an overly rosy promise. To go further on the field side, see the best practices for heat pump installation. Argile applies the same caution and turns the SCOP of the chosen equipment into savings shown to the client.
In 2026: performance, grants and requirements to anticipate for your heat pump jobs
What performance levels are generally expected in grant applications (MaPrimeRénov'/CEE)
In practice, applications require clearly documented seasonal performance. For a heat pump, this relies on manufacturer data (SCOP, ETAS), certification (NF PAC, Eurovent where applicable) and consistent sizing relative to the home and its emitters. On the CEE side, thresholds and required documents are set by the standardised operation sheets.
Heat pumps and RGE: evidence, documents and traceability to keep for securing your grants
Keep complete traceability. The quote and invoice must specify make, reference, serial number, output, control type, accessories, and commissioning. Add the current RGE certificate, the CEE sworn statement, the manuals, and a few photos (before, after, rating plate) to avoid getting stuck during an audit. To go further on what to keep and how to prepare for an audit, see our article on preparing your job sites and documents.
2026 checklist: checks before handover to guarantee the advertised performance
Before handover, aim for clean final settings.
- Sizing, weather compensation curve, backup heat and DHW setpoints validated.
- Clean circuit (flushed if needed), filter and dirt separator in place, flow rates balanced.
- Pipe insulation, condensate drains, noise levels and clearances respected.
- Commissioning report, client walkthrough, maintenance schedule handed over.
