EPC retrofit cost

The government response of 21 January 2026 confirmed the plan for every privately rented home to meet the new band C standard by 1 October 2030, with no earlier date for new tenancies. The regulations are still to be made. Until then the band E minimum under the Energy Efficiency (Private Rented Property) Regulations 2015 stays in force. The cost cap for the new standard is £10,000 per property, or 10% of the value for a home worth under £100,000, and an exemption will be available where meeting the standard would cost more. The regulations are aimed to come into force in 2027.

Retrofit costs are dominated by a small number of measures. For a typical 1930s three-bed semi at band D, hitting band C usually means topping up loft insulation to 270mm (£300–500), confirming cavity-wall insulation is in place (£500–1,200 if not), upgrading single or part-double glazing to A-rated double or triple (£6,000–12,000 for a full-house refit) and either installing a high-efficiency condensing boiler with smart controls (£2,500–4,000) or beginning the transition to a low-temperature heat pump (£9,000–14,000 after the Boiler Upgrade Scheme £7,500 grant). Solid-wall properties (no cavity to fill) are the highest-risk archetype: external or internal solid-wall insulation alone runs £12,000–20,000 and is often the difference between hitting band C and applying for an exemption.

Property archetype matters more than postcode for the headline number. A purpose-built 1990s flat with cavity walls and gas combi boiler typically reaches band C from band D for under £2,500. A pre-1919 mid-terrace with solid walls, single-glazed sash windows, an old open-flue boiler and a roof in poor repair can exceed the £10,000 cap on the glazing line item alone. The calculator picks the cheapest credible measure stack to move from the current band to band C, surfaces the per-measure cost, and flags the exemption candidate when the cheapest stack still exceeds the cap.

Funding helps but does not change the cap arithmetic much. Warm Homes: Local Grant, run by councils to 31 March 2028, can fully fund one home per landlord for lower-income households in EPC D to G homes, and ECO4 runs until 31 December 2026. Both count towards the £10,000 cap as spending. The Boiler Upgrade Scheme gives £7,500 towards an air or ground source heat pump and does not count towards the cap. The Great British Insulation Scheme closed on 31 March 2026.

Doing nothing is no longer cheap. From 1 October 2030 a home below the standard cannot be let without a registered exemption, whether the tenancy is new or existing. The government plans a maximum penalty of £30,000 per property for each breach, up from £5,000, once new legislation is passed. Planning the work in 2026 and 2027, while installers are available, avoids competing with every other landlord just before the deadline.

This calculator is a planning aid, not a building survey. Use the output to set an upper budget, decide which funding to pursue and judge whether an exemption is likely. For the actual specification, commission a retrofit survey: the EPC alone does not capture the right route, and some cheap-on-paper measures create condensation and damp risk if installed without a whole-house assessment.