Many homeowners focus on insulation, boilers, or double glazing to improve their EPC rating, but one factor often overlooked is air leakage. Hidden drafts and leaks allow heat to escape, forcing your heating system to work harder, increasing energy bills, and lowering your EPC score.

Understanding and fixing these “silent EPC killers” is essential to improving energy efficiency. For professional guidance, our EPC Assessors in London can evaluate your home and identify problem areas:
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1. What Are Hidden Air Leaks?

Air leaks are small gaps or cracks in your building envelope where warm air escapes or cold air enters. Common locations include:

  • Around window and door frames

  • Loft hatches and ceiling junctions

  • Gaps in floorboards or skirting

  • Chimneys, flues, and ventilation ducts

  • Pipe and cable penetrations

Even minor leaks can significantly reduce your EPC score because they increase the home’s energy demand.

2. How Air Leaks Affect Your EPC Rating

EPC assessors calculate energy efficiency based on potential heat loss. Air leaks contribute to:

  • Increased SAP-calculated energy usage

  • Lower predicted efficiency

  • Reduced EPC band

A property may have excellent insulation and a modern boiler but still receive a lower EPC due to uncontrolled drafts.

3. Common Hidden Air Leak Locations

✔ Windows and Doors

Check for poorly fitted frames, missing seals, or gaps around sills and lintels.

✔ Loft and Roof Areas

Loft hatches, roof junctions, and gaps around chimneys are frequent culprits.

✔ Floors and Skirting Boards

Gaps between floorboards or at skirting edges allow heat to escape unnoticed.

✔ Pipework and Ducts

Unsealed penetrations for plumbing, heating, or electrical cables create hidden pathways for cold air.

4. How to Detect Hidden Air Leaks

Detecting leaks often requires more than a visual inspection. Effective methods include:

  • Thermal imaging surveys to reveal temperature differences

  • Blower door tests to measure home airtightness

  • Professional EPC assessments that identify draft sources

Book a professional assessment to pinpoint hidden leaks:
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5. Solutions to Reduce Air Leakage

Fixing air leaks improves both EPC ratings and home comfort:

  • Install draught-proofing around doors and windows

  • Seal gaps around loft hatches and roof edges

  • Insulate floorboards and skirting junctions

  • Seal pipe and cable penetrations with appropriate materials

  • Ensure chimneys and vents are properly fitted or capped

Providing evidence of these improvements to your assessor can help raise your EPC score. Learn more about our EPC services:
👉 https://epcrate.co.uk/about-us-epc-company-london/

6. Why Air Leaks Are Often Overlooked

Homeowners often assume insulation or a new boiler solves all energy efficiency issues. However, hidden air leaks are invisible and frequently overlooked. The EPC calculation defaults to higher heat loss unless these issues are documented and fixed.

If you suspect air leaks are lowering your EPC, our team can help:
👉 https://epcrate.co.uk/contact-us-epc-services-london/

Conclusion

Hidden air leaks are silent efficiency killers that can lower your EPC rating even in well-insulated homes. Detecting and addressing them ensures:

  • Higher EPC ratings

  • Lower energy bills

  • Improved comfort and property value

    Email :info@epcrate.co.uk

    Phone:020 34884142