Heat Pump Efficiency Ratings Explained: SCOP, COP, A+++, and What They Actually Mean
Energy efficiency is the number one reason people switch to heat pumps. But walk into any conversation about heat pump efficiency and you'll quickly encounter a thicket of acronyms: COP, SCOP, A+++, ErP, SPF. They all measure efficiency — but in different ways, under different conditions, for different purposes.
Understanding these ratings isn't just academic. It's the difference between a heat pump that saves you €800 a year and one that saves you €300. It affects your eligibility for government subsidies. And it determines how well your heat pump performs in the depths of winter, when you need it most.
COP vs SCOP: The Critical Difference
This is the most common point of confusion — and the most important to understand.
COP (Coefficient of Performance)
COP measures efficiency at a single, fixed operating point — typically A7/W35 (7°C outside air, 35°C water output). If a heat pump has a COP of 4.5 at A7/W35, it means it delivers 4.5 kW of heat for every 1 kW of electricity consumed — at that specific temperature.
The problem? Your heat pump doesn't operate at A7/W35 all year. In January, when it's -5°C outside and you need 55°C water for your radiators, the COP might drop to 2.5. COP alone tells you almost nothing about real-world annual performance.
SCOP (Seasonal Coefficient of Performance)
SCOP is the number that actually matters. It calculates weighted efficiency across an entire heating season, accounting for:
- Varying outdoor temperatures throughout the year
- Different heating load requirements at different temperatures
- Part-load operation (heat pumps rarely run at full capacity)
- Three designated European climate zones
A SCOP of 4.5 means that, averaged across a full heating season in your climate zone, you get 4.5 kWh of heat from every 1 kWh of electricity. This is the number to compare between models — not COP.
| Rating | What It Measures | When to Use It |
|---|---|---|
| COP | Efficiency at one fixed point (A7/W35) | Technical comparisons, lab testing |
| SCOP | Seasonal average across all conditions | Real-world cost estimation, subsidy eligibility |
| SPF | Actual measured field performance | Post-installation verification |
The ErP Energy Label: A+++ to D Explained
Since 2015, all heat pumps sold in the EU must carry the ErP (Energy-related Products) energy label. For heat pumps, the scale runs from A+++ (best) to D (worst) — though since 2019, new products must achieve at least A+.
What Each Rating Means
| ErP Class | SCOP (Average Climate, 35°C) | Annual Efficiency |
|---|---|---|
| A+++ | ≥ 5.10 | Exceptional — top-tier performance |
| A++ | 4.60 - 5.09 | Excellent — typical for premium models |
| A+ | 4.00 - 4.59 | Good — minimum for new installations |
| A | 3.40 - 3.99 | Acceptable — older or budget models |
| B | 2.80 - 3.39 | Below current standards |
| C | 2.20 - 2.79 | Poor — likely pre-2015 equipment |
| D | < 2.20 | Very inefficient — consider replacement |
The Catch: Climate Zone Matters
An A+++ rated heat pump in the "Average" climate zone (Strasbourg) might only achieve A++ in the "Colder" zone (Helsinki) and A+ when delivering 55°C instead of 35°C. Always check which climate zone and flow temperature the rating is based on.
The three European climate zones are:
- Warmer (Athens): mild winters, low heating demand
- Average (Strasbourg): moderate winters, typical heating demand
- Colder (Helsinki): severe winters, high heating demand
How SCOP Is Calculated
SCOP is defined by EN 14825 and calculated as:
SCOP = Total Seasonal Heat Output ÷ Total Seasonal Electricity Input
The calculation uses a bin method — dividing the heating season into temperature bins, each with:
- Hours per year at that temperature (based on climate zone data)
- Heating load at that temperature (based on building heat loss)
- COP at that temperature (based on manufacturer test data)
The weighting is heavily biased toward moderate temperatures (2-12°C), where heat pumps spend most of their operating hours. This is good design — it reflects reality — but it also means that a heat pump with excellent mid-range efficiency can achieve a high SCOP even if its performance drops significantly in extreme cold.
What to check: Look for the SCOP at your climate zone and your required flow temperature. A heat pump with SCOP 4.8 at 35°C might drop to 3.2 at 55°C — a critical distinction for radiator-based systems.
Other Efficiency Metrics You Should Know
SPF (Seasonal Performance Factor)
SPF is the measured, real-world equivalent of SCOP. It's calculated from actual energy meter readings over a full year. If your installer promises a SCOP of 4.5 but you measure an SPF of 3.8, something is wrong — typically incorrect sizing, poor system design, or user error.
The UK's Renewable Heat Incentive and various EU subsidy schemes increasingly require SPF measurement and reporting.
ESEER (European Seasonal Energy Efficiency Ratio)
Primarily used for cooling and reversible heat pumps. Measures seasonal cooling efficiency, weighted similarly to SCOP but for summer operation.
ηs (Seasonal Space Heating Energy Efficiency)
The percentage value shown on the ErP label. For an A+++ heat pump, ηs ≥ 200% (meaning it's more than twice as efficient as a reference electric heater).
How to Compare Heat Pumps Using Efficiency Ratings
- Start with SCOP, not COP. If a manufacturer only quotes COP, ask for the SCOP data.
- Match the climate zone. Compare SCOPs from the same climate zone — usually "Average" for most of Western and Central Europe.
- Match the flow temperature. 35°C (underfloor heating) and 55°C (radiators) produce very different SCOPs. Compare like with like.
- Check the test standard. EN 14825 is the current standard. Older EN 14511 tests use different conditions and aren't directly comparable.
- Look at the part-load performance. A unit with good part-load efficiency will perform better in mild weather (most of the heating season).
- Don't obsess over fractions. The difference between SCOP 4.6 and 4.8 is about 4% in running costs — often less than the variation caused by installation quality.
Real Cost Savings: What Efficiency Means in Euros
Let's run the numbers for a typical European home with 12,000 kWh annual heat demand:
| SCOP | Electricity Used | Annual Cost (@ €0.25/kWh) | vs Gas Boiler (@ €0.10/kWh) |
|---|---|---|---|
| 3.0 | 4,000 kWh | €1,000 | Break-even |
| 3.5 | 3,429 kWh | €857 | Save €343 |
| 4.0 | 3,000 kWh | €750 | Save €450 |
| 4.5 | 2,667 kWh | €667 | Save €533 |
| 5.0 | 2,400 kWh | €600 | Save €600 |
The jump from SCOP 3.5 to 4.5 saves about €190 per year — nearly €3,000 over a 15-year lifespan. This is why investing in a higher-rated heat pump almost always pays for itself.
Frequently Asked Questions
Q: Is A+++ always better than A++? Generally yes, but the difference may be smaller than you think. An A+++ unit with SCOP 5.15 vs an A++ unit with SCOP 5.05 differ by only 2% in annual energy use. Focus on the actual SCOP number, not just the letter grade.
Q: Can an old heat pump achieve a modern A+++ rating? No. Heat pumps installed before 2015 typically achieve B or C ratings by today's standards. If your heat pump is 10+ years old, replacement could reduce your electricity consumption by 30-50%.
Q: Does the energy label account for defrost cycles? Yes. The EN 14825 test procedure includes defrost energy in the SCOP calculation, though real-world defrost consumption can be higher in particularly humid climates.
Q: Why does my heat pump's real performance seem lower than the SCOP? Common causes: incorrect sizing, poorly balanced heating system, incorrect weather compensation settings, excessively high flow temperatures, or a building with higher heat loss than assumed.
Q: Do all Thermovo heat pumps achieve A+++? Our R290 monobloc and premium R32 ranges achieve A+++ across all climate zones at 35°C flow temperature. Check individual product pages for detailed ErP label data.
Efficiency ratings are based on EN 14825 test standards. Actual performance depends on correct system design, installation quality, and building characteristics.