Quick Answer
SCOP = Seasonal Coefficient of Performance. It measures heat pump efficiency across a full year. SCOP of 3.5 means you get 3.5 kW of heat for every 1 kW of electricity. That's 350% efficiency.
SCOP stands for Seasonal Coefficient of Performance. It's the standard way to measure heat pump efficiency in the UK and EU.
SCOP = Heat Output ÷ Electricity Input
Example:
💡 Why Heat Pumps Are "More Than 100% Efficient"
Heat pumps don't create heat—they move it from outside air into your home. Like a fridge in reverse. This process uses way less energy than burning gas to create heat.
| Metric | What It Measures | When Used |
|---|---|---|
| SCOP | Seasonal average (whole year) | Official ratings, grants, comparisons |
| COP | Performance at specific temperature | Technical specs, lab testing |
Use SCOP for real-world comparisons. COP might show 4.5 at +7°C outdoor temp, but SCOP (which averages across UK's variable weather) gives you the actual annual efficiency you'll get.
| SCOP Range | Rating | Notes |
|---|---|---|
| 4.0+ | Excellent | Top-tier models, well-insulated homes |
| 3.5-3.9 | Very Good | Most modern heat pumps in UK |
| 3.0-3.4 | Good | BUS grant minimum, still saves money vs gas |
| 2.5-2.9 | Acceptable | Older models or challenging installations |
| Below 2.5 | Poor | Not eligible for BUS grant |
⚠️ BUS Grant Requirement
To qualify for the £7,500 Boiler Upgrade Scheme grant, your heat pump must achieve SCOP of 2.8 or higher. Most modern systems easily exceed this (3.5+ is common).
| System | Efficiency | Energy Used | Annual Cost |
|---|---|---|---|
| Gas boiler (90% efficient) | 0.9 | 22,222 kWh gas | £1,555 (7p/kWh) |
| Heat pump (SCOP 2.5) | 2.5 | 8,000 kWh elec | £1,920 (24p/kWh) |
| Heat pump (SCOP 3.0) | 3.0 | 6,667 kWh elec | £1,600 (24p/kWh) |
| Heat pump (SCOP 3.5) | 3.5 | 5,714 kWh elec | £1,371 (24p/kWh) |
| Heat pump (SCOP 4.0) | 4.0 | 5,000 kWh elec | £1,200 (24p/kWh) |
Key Takeaway: A 0.5 increase in SCOP (e.g., 3.0 to 3.5) saves you £230/year. Over 20 years, that's £4,600 saved.
💰 Price Cap Update (2026)
Using current UK rates: Gas 7p/kWh, Electricity 24p/kWh. Even at SCOP 3.0, heat pumps cost similar to gas. At SCOP 3.5+, they're cheaper.
| Setup | Typical SCOP | Why? |
|---|---|---|
| Underfloor heating + good insulation | 4.0-4.5 | Low flow temps (35-40°C) = peak efficiency |
| Oversized radiators + good insulation | 3.5-4.0 | Can run at 45-50°C flow temp |
| Existing radiators + moderate insulation | 3.0-3.5 | Needs 55-60°C, still efficient |
| Small radiators + poor insulation | 2.5-3.0 | Requires 65-70°C, lower efficiency |
| Ground source heat pump | 4.0-5.0 | Ground temp stable year-round |
Flow temperature is the water temperature leaving your heat pump. Lower = better efficiency.
| Flow Temperature | Typical SCOP | Use Case |
|---|---|---|
| 35-40°C | 4.0-4.5 | Underfloor heating |
| 45-50°C | 3.5-4.0 | Oversized radiators, mild days |
| 55-60°C | 3.0-3.5 | Standard radiators, cold days |
| 65-70°C | 2.5-3.0 | Small radiators, very cold days |
💡 Weather Compensation Saves Money
Modern heat pumps automatically lower flow temp on mild days. This can boost average SCOP by 0.3-0.5 compared to fixed-temp systems.
| System | Efficiency | How It Works |
|---|---|---|
| Modern gas combi boiler | 90-95% | Burns gas to create heat. Can't exceed 100%. |
| Older gas boiler | 70-80% | 20-30% of heat escapes up flue |
| Heat pump (SCOP 3.0) | 300% | Moves heat instead of creating it |
| Heat pump (SCOP 4.0) | 400% | 4 kW heat from 1 kW electricity |
Why this matters: Even with electricity costing 3x more than gas per kWh (24p vs 7p), a heat pump with SCOP 3.5 costs about the same to run as a gas boiler. SCOP 4.0+ is actually cheaper.
Most accurate method:
Rough estimate using bills:
Most installers can measure:
Manufacturer SCOP is tested in ideal lab conditions (well-insulated test room, perfect setup). Your installer is giving you a realistic SCOP based on your home's insulation, radiators, and flow temperature requirements. Trust the installer's estimate.
Yes, but SCOP is a seasonal average that already accounts for this. On a -5°C day, COP might be 2.8, but on a +10°C autumn day it might be 4.5. Averaged across the UK's mild climate, you still get 3.5+ SCOP.
Yes! Lower your flow temperature (if radiators allow), improve insulation, install weather compensation, and keep filters clean. Some homes improve SCOP by 0.5-1.0 points with these tweaks.
No. SCOP is for heating. SEER (Seasonal Energy Efficiency Ratio) is for cooling. Most UK heat pumps don't have cooling, so SCOP is what matters.
✅ Good News
Virtually all modern heat pumps easily exceed the 2.8 minimum. Most MCS-certified installations achieve 3.2-4.0 SCOP in real-world UK conditions.
Our free calculator connects you with MCS-certified installers who will assess your home and give you a realistic SCOP estimate—not just the manufacturer's lab numbers.
Free Heat Pump Calculator£8k-£14k before grant. £500-£6,500 after £7,500 BUS grant.
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How heat pumps perform in cold UK weather down to -5°C.
70% of homes can. Heat Loss Survey tells you for sure.