You’ve installed a heat pump—clean, efficient, eco-friendly. You’re expecting your EPC rating to jump… but it doesn’t.
In fact, some homeowners see no improvement at all. Worse still, others report a drop in their score.
How can this be?
Welcome to the frustrating intersection of modern technology and old-fashioned bureaucracy—where EPC methodology often struggles to keep up with the low-carbon promise of heat pumps.
1. Heat Pumps Are Incredibly Efficient—So What’s the Problem?
Modern air-source and ground-source heat pumps operate at 300–400% efficiency, meaning for every 1 kWh of electricity used, you get 3–4 kWh of heat.
That should be a guaranteed EPC win, right?
Not necessarily.
Because EPCs use Standard Assessment Procedure (SAP) software that:
Assumes “average” installation performance
Penalises electric systems when electricity is rated with a high primary energy factor
May ignore real-world COP (Coefficient of Performance) unless tested and documented
👉 Your £12,000 upgrade might get buried in flawed assumptions and poor data.
2. Electricity’s Dirty History Is Still Hurting Heat Pumps
Although the UK grid has become cleaner, EPCs still rely on standardised energy and carbon factors—and these change slowly.
Until recently:
Electricity was seen as carbon-heavy
Gas, bizarrely, looked better in EPC scoring
Heat pumps got scored down for being electric, despite being ultra-efficient
SAP 10 has corrected some of this, but many EPCs are still being issued under older systems like SAP 2012.
3. Assessor Knowledge (and Tools) Are Inconsistent
EPC scores depend heavily on how the assessor inputs:
Heat pump model and specification
Installation quality
Control system types
Backup heaters (which can unfairly skew results)
If your assessor lacks:
Training on low-carbon systems
Access to updated product databases
The right software tools…
…your heat pump might not get the credit it deserves.
4. Missing Documentation = Missed EPC Points
Heat pump performance must be verified with MCS certificates or SAP inputs. If you can’t provide:
Manufacturer performance data
Installation paperwork
MCS installer credentials
Then the assessor may use default values, which are often conservative or pessimistic.
👉 The result? Your high-efficiency system gets treated like a generic electric heater.
5. The Bureaucratic Catch-22: EPC vs. Real Emissions
Here’s the paradox:
Your EPC may rate your gas boiler home as better than your electrified one…
…even though your carbon footprint is drastically lower with a heat pump.
That’s because EPCs:
Prioritise running costs and primary energy, not just emissions
Lag behind real-world decarbonisation of the UK electricity grid
Still don’t fully integrate real-time usage data (despite smart meter rollout)
How to Avoid a Heat Pump EPC Nightmare
✅ Hire a heat pump-literate EPC assessor—ask about their SAP version and heat pump experience.
✅ Keep all documentation: MCS certificate, spec sheets, installer details.
✅ Use smart controls—some EPCs award points for time/temp zoning and thermostatic efficiency.
✅ Consider a new EPC if yours was issued under SAP 2012—the newer SAP 10 is more fair to electric systems.
✅ Factor in future EPC reforms that favour electrification and penalise fossil fuels.
Final Thought: The System Needs to Catch Up
Heat pumps are a cornerstone of the UK’s net-zero strategy. But EPCs, in their current form, often fail to reflect that.
Until SAP fully rewards low-carbon performance—and assessors are equipped to model it properly—your EPC might continue to underplay your biggest energy upgrade.
📍 Final Takeaway
The EPC graph is just the beginning. When you know how to read between the lines, your report becomes more than a score—it becomes a blueprint for saving energy, reducing emissions, and increasing property value.
Ready to unlock the full story of your EPC?
📅 Book your expert EPC assessment today at EPCrate.co.uk.
