Energy Performance Certificates in London: What They Are, How the Rating is Calculated, and How to Improve Yours

Booking an EPC: An EPC can only be produced by an accredited Domestic Energy Assessor (DEA) — a person who has completed an accredited training course in domestic energy assessment and is registered with one of the government-approved accreditation schemes (Elmhurst Energy, ECMK, Stroma Certification, NAPIT, or Quidos). Unaccredited "EPC" certificates are not valid for legal purposes.

The assessment visit: The DEA visits the property for approximately 30–90 minutes (longer for larger properties, shorter for small flats). During the visit, the assessor records: The property type, floor area, and age of construction. The wall construction (solid masonry, cavity masonry, timber frame, etc.) and whether insulation is present. The floor construction (suspended timber, solid concrete, or other) and whether floor insulation is present. The roof construction and whether accessible or inaccessible loft insulation is present. The window type and age (single glazed, double glazed, secondary glazed, triple glazed). The main space heating system: boiler type, fuel, and approximate age; heat pump type; electric storage heaters; district heating. The hot water system: combi boiler (no cylinder); cylinder-based system; immersion heater; solar thermal. The presence of photovoltaic panels or other renewable energy systems. The lighting type and percentage of low-energy lighting. The presence and type of mechanical ventilation (MVHR, extract only, or natural ventilation).

The assessor uses a tablet or laptop to record the data and input it into the RdSAP (Reduced Standard Assessment Procedure) software. The output is the EPC rating and the recommendation report, which are uploaded to the national EPC register (accessible at find-energy-certificate.service.gov.uk).

Cost: A residential EPC for a standard London terraced house typically costs £60–£120. Some conveyancers and estate agents arrange EPCs as part of a property marketing package.

Every EPC is accompanied by a recommendation report listing the measures that could improve the property's energy efficiency rating. The recommendations are generated automatically by the RdSAP software based on the property type and the data recorded during the survey. They are not a bespoke professional opinion — they are a standard set of potential measures applicable to the property type.

Common recommendations for a Victorian London terrace and their typical SAP score impact:

Loft insulation (top up to 270mm): Typical cost: £300–£500 (often partly or fully covered by ECO4 government scheme grants). Typical SAP score improvement: 3–6 points. EPC band movement: may move a D to a C if the property is near the D/C boundary.

Solid wall insulation (internal or external): Typical cost: £8,000–£15,000 for a standard terrace (external); £5,000–£10,000 (internal). Typical SAP score improvement: 5–10 points. EPC band movement: can move an E to a D or a D to a C in many cases.

High-efficiency condensing gas boiler (replacing old G-rated boiler): Typical cost: £2,000–£4,000 installed. Typical SAP score improvement: 3–8 points. EPC band movement: significant for properties with old inefficient boilers — may move a D to a C.

Heat pump (air source, replacing gas boiler): Typical cost: £10,000–£18,000 installed, minus £7,500 Boiler Upgrade Scheme grant = net £2,500–£10,500. Typical SAP score improvement: this is complex — a heat pump can improve or worsen the SAP score depending on the property's insulation level and the SAP assumptions about heat pump seasonal performance. A well-insulated property with an efficient heat pump can achieve a C or B rating. A poorly insulated Victorian terrace with a heat pump may not perform as well as expected on the SAP model because the higher SAP electricity cost factor for electricity vs gas affects the fuel cost calculation.

Solar PV: Typical cost: £5,000–£9,000 for a 4kWp system. Typical SAP score improvement: 5–15 points (depends on the roof area, orientation, and shading). EPC band movement: a well-sized PV system on a south-facing roof can move a D property to a C or B.

Double glazing (replacing single glazing): Typical cost: £5,000–£12,000 for a whole house (depends on number of windows and specification). Typical SAP score improvement: 2–5 points. EPC band movement: one of the smaller individual improvements in isolation but contributes meaningfully combined with other measures.

ECO4 government scheme: The Energy Company Obligation (ECO4) scheme funds energy efficiency improvements for owner-occupiers and private tenants in properties with an EPC rating of D, E, F, or G, and where the household is in fuel poverty or receives certain means-tested benefits. The scheme is delivered by the major energy suppliers and can fund insulation, boiler replacement, and heat pump installation at no cost or at reduced cost to eligible households. Eligibility should be checked via the government's Simple Energy Advice (SEA) service before commissioning privately-funded improvement works.

Current MEES rules (England and Wales, 2024–2025): Since 1 April 2018, it has been unlawful to grant a new assured shorthold tenancy (AST) for a residential property with an EPC rating below E (EPC F or G). Since 1 April 2020, the MEES requirement was extended to cover all existing ASTs — not just new tenancies. A landlord cannot continue to let a property with an EPC F or G rating regardless of when the tenancy began. Exemptions apply where: the landlord can demonstrate that the cost of bringing the property to EPC E would exceed £3,500 (including any grants and funding obtained); or where all the relevant recommended energy efficiency improvements have been made and the property still cannot reach EPC E (the "all relevant improvements made" exemption). Exemptions must be registered on the PRS Exemptions Register.

Enforcement: Local authorities are responsible for enforcing MEES. A landlord who lets a property in breach of MEES can be issued with a compliance notice and a financial penalty of up to £4,000 for each breach.

Future MEES proposals (as of mid-2025): The government consulted on requiring private rented sector properties in England to achieve a minimum EPC C rating by: 2025 for new tenancies; and 2028 for all tenancies. These proposals have not been enacted into law as of mid-2025. The current minimum remains EPC E. Landlords should monitor for future legislation and plan EPC improvement works accordingly — the cost cap under the proposed EPC C MEES was proposed at £10,000 per property.

Social rented sector: The social housing sector (housing associations and local authority housing) has its own energy efficiency targets under Awaab's Law and the Social Housing Decarbonisation Fund — separate from the private rented MEES framework.