Sources

Primary regulation and official guidance first, professional method second, and nothing quoted from memory as fact.

• Directive (EU) 2024/1275 - the recast Energy Performance of Buildings Directive, official text.
• European Commission: Energy Performance of Buildings Directive - EU policy pages on the EPBD and building renovation.
• UK Government: Energy Performance Certificates - when an EPC is needed and how the UK system works.
• UK Government: Find an energy certificate - the UK EPC register.
• UK Government: Domestic private rented property minimum energy efficiency standard - landlord guidance for England and Wales.
• Energy Saving Trust - independent advice on home energy, insulation, heating and renewables.
• BRE Group - building research behind SAP and UK energy assessment methods.
• Ofgem - UK energy regulator pages on meters, suppliers and consumer protections.
• International Energy Agency - global analysis of buildings energy and retrofit.
• CIBSE - professional guidance on building services, heating and ventilation.
• MCS - certification for small-scale renewable installers and products in the UK.
• TrustMark - UK quality scheme for home improvement work, including retrofit.