Adding a home extension or loft conversion can increase living space and property value, but it also has implications for your Energy Performance Certificate (EPC) rating. Understanding these impacts ensures your new addition doesn’t lower energy efficiency or compliance.

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 additional surfaces that may lose heat if not properly insulated

  • Poor planning can negatively impact your EPC score

2. Key Factors to Consider in Home Additions

a. Insulation

  • Walls, floors, and loft areas in extensions should be properly insulated

  • Matching insulation standards with the existing property prevents heat loss

b. Windows and Doors

  • Large windows, French doors, or skylights may reduce thermal efficiency

  • Use energy-efficient glazing and ensure airtight sealing

c. Heating Integration

  • Extend heating systems efficiently using zoned heating or thermostatic radiator valves (TRVs)

  • Ensure the new space is fully integrated into the existing system

d. Ventilation and Air Tightness

  • Seal gaps around walls, floors, and ceilings

  • Consider mechanical ventilation with heat recovery (MVHR) for larger extensions

e. Renewable Energy Options

  • Solar panels or heat pumps can offset energy loss from new spaces

  • Positively affects EPC ratings and lowers running costs

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 how your extension impacts EPC rating

  • Recommend practical solutions to maintain or improve scores

  • Provide updated 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