EPC Ratings in London: How to Improve Your Energy Performance Certificate

An EPC is produced by an accredited domestic energy assessor (DEA) who inspects the property and uses the Standard Assessment Procedure (SAP) to calculate an estimated energy cost and an efficiency rating. The rating bands: A (92-100): most efficient. Rare in the London housing stock — mainly found in new-build or recently deep-retrofitted properties. B (81-91): very efficient. Uncommon in the Victorian/Edwardian stock. Found in 1990s-2000s new builds with good insulation and efficient heating. C (69-80): the current government target for rental properties and the aspiration for most London homeowner retrofit programmes. D (55-68): the most common band for London Victorian terraces and inter-war properties with some improvement — loft insulation and a modern boiler but no wall insulation. E (39-54): typical of an unimproved or partly improved Victorian London terrace — no loft insulation, old boiler, solid walls uninsulated. F (21-38): poor. An unimproved Victorian London terrace with no modern improvements. G (1-20): very poor. Uncommon in London; typically found in older properties with electrical storage heating, no insulation, and no double glazing. The SAP methodology: the EPC is not a measured energy consumption figure — it is a modelled estimate based on the property's construction characteristics (wall type, insulation, window type, heating system, hot water system, etc.) rather than actual energy bills. This means two identical properties with different occupant behaviours will receive the same EPC score.

EPC requirements for rental properties in England are set by the Minimum Energy Efficiency Standards (MEES): Current requirement (in force): a property let under a new or renewed tenancy since April 2018 must have an EPC rating of E or above. Properties rated F or G cannot legally be let (subject to exemptions). Proposed changes: the government has consulted on raising the minimum EPC requirement for rental properties to C by 2030 (initially proposed as 2025-2028, but repeatedly deferred). As of 2025-2026, the requirement remains E — but the trajectory toward C by 2030 is well-established and London landlords should plan for it. What this means for London landlords practically: any London rental property currently at E should be considered compliant but at risk. Properties at F or G are currently unlettable without an exemption. Planning for the EPC-C target by 2030 is prudent — improvements made now will be more cost-effective than improvements made under time pressure. Exemptions: registered exemptions are available where the cost of improvement exceeds £3,500 with no grant funding available, where third-party consent is needed and refused, or where the improvement would devalue the property by more than 5%. Exemptions last for 5 years and must be renewed.

The SAP-based EPC assessment rewards specific improvements in the following approximate order of impact: 1. Boiler and heating controls (highest EPC impact per £): replacing an old G-rated (40-60% efficiency) gas boiler with a modern A-rated condensing combi boiler (90-94% efficiency) is the single most cost-effective EPC improvement. Typical impact: +5 to +15 SAP points. Cost: £2,000-£3,500. Improved heating controls (programmer, thermostatic radiator valves, room thermostat): +2 to +5 SAP points. Cost: £200-£600. 2. Loft insulation (free or low cost via grant): topping up loft insulation to 270mm recommended depth. Impact: +3 to +8 SAP points. Cost: £300-£600 (often grant-funded via ECO4/GBIS — potentially free). 3. Cavity wall insulation (for eligible properties only): +3 to +10 SAP points. Cost: £400-£1,000 (often grant-funded). 4. Internal or external solid wall insulation (for Victorian solid-brick properties): a major intervention but also the largest SAP impact for a Victorian property. +8 to +20+ SAP points. Cost: £4,000-£20,000. 5. Double or triple glazing (if currently single-glazed): +2 to +8 SAP points for full house re-glaze. Cost: £5,000-£15,000 for a full London terrace. 6. Solar PV panels: +4 to +12 SAP points. Cost: £5,000-£10,000 before export tariff revenue. 7. Heat pump (air source): replaces gas boiler, can generate significant SAP improvement if correctly sized and installed with adequate insulation. SAP impact varies significantly depending on property insulation level — a poorly insulated property may see limited SAP gain from a heat pump. Cost: £8,000-£14,000.

An EPC assessment for a London residential property: cost: £60-£150 for a standard domestic EPC assessment. The assessor visits the property (typically 30-60 minutes for a house) and uses the DEA software to generate the certificate. The certificate is valid for 10 years from the date of issue. A new EPC assessment is not required until the current one expires or until significant energy improvements have been made that would change the rating. Who can provide an EPC: only an accredited Domestic Energy Assessor (DEA) can issue a valid EPC. Find accredited DEAs on the Ofgem EPC Register or through the Elmhurst, NHER, or CIBSE accreditation directories. EPC lodgement: all EPCs must be lodged on the government's national EPC register at epcregister.com. You can check whether a current valid EPC exists for a property using this register before commissioning a new one — if a valid EPC was issued within the past 10 years, a new one is not needed unless improvements have been made. When an EPC is required: before selling a property; before letting a property; when a building is newly constructed; when selling or letting a commercial property (a separate non-domestic EPC is required).

The growing importance of EPC ratings to the London property market: Property values: research consistently shows a premium for higher EPC-rated London homes. DLUHC data suggests properties with an EPC of C or above achieve 5-10% higher sale prices than equivalent properties with an E or F rating. The gap is likely to widen as EPC requirements for rental properties tighten and as buyers increasingly value energy cost certainty. Mortgages: a growing number of UK lenders (including Nationwide, Halifax, and NatWest) offer green mortgage products with preferential interest rates for properties with an EPC rating of C or above. The interest rate saving can be 0.1-0.25% — on a £400,000 London mortgage this is a saving of £400-£1,000 per year. For London landlords, a BTL property at EPC-C may attract better BTL mortgage terms. EPC and the retrofit movement: the Energy Efficiency Infrastructure Group and UK100 have consistently advocated for incentivising EPC improvement in London's housing stock. The direction of travel — toward a mandatory EPC-C for sales and lettings — is well-signalled. London homeowners who invest in EPC improvement today are reducing future compliance risk and improving asset value.