See exactly how much your EPC band could improve with each retrofit measure. Based on UK SAP methodology used by accredited Domestic Energy Assessors.
Your improvement breakdown
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Book a free survey →How is this calculated? (SAP methodology)
The UK EPC system uses the Standard Assessment Procedure (SAP) to score homes 1–100. The score determines the band:
| Band | SAP score |
|---|---|
| A | 92–100 |
| B | 81–91 |
| C | 69–80 |
| D | 55–68 |
| E | 39–54 |
| F | 21–38 |
| G | 1–20 |
Each measure adds an estimated SAP point gain based on industry averages. Actual SAP gain depends on house specifics (wall area, current heating efficiency, etc). For a definitive EPC prediction, get a survey from an accredited Domestic Energy Assessor.
Detached houses gain slightly more from wall insulation (more wall area per occupant), so the calculator weights gains accordingly. The maximum SAP score is 100 (no measure stacking can take a house above that).
Source: BRE SAP 10.2 methodology, Building Research Establishment EPC research.