The EPC is generated by an accredited domestic energy assessor on a property visit. It evaluates insulation, glazing, heating system, and renewable-energy installations. The certificate shows the current rating + a "potential" rating after recommended improvements.
From April 2025 the UK is moving toward EPC C as the minimum for newly-rented properties (Minimum Energy Efficiency Standard — MEES). Existing tenancies follow on a staggered timeline. Buy-to-let landlords with sub-C properties need a remediation plan or risk fines + restricted re-letting.
For buyers, the EPC is a leading indicator of running costs + future capital-value risk. A C-rated property in 2026 may need £20-50k of works by 2030 to remain lettable.