Home extensions and loft conversions can increase living space and property value—but they can also affect your Energy Performance Certificate (EPC) rating if energy efficiency is not carefully considered. Understanding the key factors helps homeowners and landlords maintain or improve EPC scores while expanding their properties.

Learn more about our professional EPC services on our About Us page.

1. Why Extensions Affect EPC Ratings

  • EPC ratings measure energy efficiency, insulation, heating, and renewable energy use

  • New additions introduce more surfaces that can lose heat

  • Poor planning or installation can negatively impact your EPC score

2. Key Factors in EPC Impact

a. Insulation Quality

  • Loft, walls, and floors in extensions must be properly insulated

  • Matching insulation to the existing property prevents heat loss

b. Windows and Doors

  • Large windows, French doors, or skylights increase natural light but may reduce thermal efficiency

  • Energy-efficient glazing and sealing are essential

c. Heating Integration

  • New rooms should integrate efficiently into the existing heating system

  • Consider zoned heating or thermostatic radiator valves (TRVs)

d. Ventilation and Air Tightness

  • Seal gaps around walls, floors, and ceilings

  • Use mechanical ventilation with heat recovery (MVHR) if needed

e. Renewable Energy Options

  • Solar panels, solar water heating, or heat pumps for the extension

  • Can offset energy losses and improve EPC scores

For guidance on EPC improvements for home additions, visit our Services – EPC Assessors London page.

3. Tips to Maintain or Improve EPC Ratings During Extensions

  • Plan energy efficiency measures from the design stage

  • Choose high-quality insulation and energy-efficient materials

  • Integrate heating and renewable energy solutions

  • Schedule an EPC reassessment after completion

Professional EPC Assessment

A certified Domestic Energy Assessor (DEA) can:

  • Evaluate the impact of your extension on EPC rating

  • Recommend practical solutions to maintain or improve scores

  • Provide accurate EPC certification for compliance, sale, or rental

Book a professional assessment via our Booking Page.

Contact Us for EPC Guidance

Want to ensure your home addition doesn’t hurt your EPC rating?
Reach out via our Contact Page for expert advice.

Email :info@epcrate.co.uk

Phone:020 34884142