When it comes to improving a property’s Energy Performance Certificate (EPC) rating, most owners focus on insulation, heating systems, and windows. But sometimes, the shape of your roof and the presence of skylights can have a surprising impact on energy efficiency scores. If you own a home or commercial property with non-standard roof angles or multiple skylights, understanding these factors is key to protecting your property’s EPC performance.
Why Roof Design Matters for EPC Ratings
The EPC assessment takes into account heat loss, insulation levels, and solar gain across different parts of the property. Roofs and skylights play a major role in this calculation because they directly affect:
Thermal efficiency – how well your roof retains heat.
Solar gains – how much sunlight contributes to natural heating.
Energy demand – the need for artificial lighting or additional heating/cooling.
👉 Learn more about the EPC process on our About Us page.
EPC Challenges with Non-Standard Roof Angles
1. Reduced Insulation Effectiveness
Non-standard or steeply angled roofs often have irregular cavities that are harder to insulate properly, leading to higher heat loss.
2. Greater Surface Area for Heat Loss
Complex roof shapes increase the exposed surface area, which can reduce energy efficiency compared to simple pitched roofs.
3. Shading and Solar Gain Variability
Depending on orientation, certain angles may limit the benefit of passive solar heating in winter — negatively impacting the EPC calculation.
How Skylights Influence EPC Ratings
✅ Potential Benefits
Natural lighting reduces the need for artificial lighting, which can improve energy efficiency.
Modern skylights with low-emissivity glazing and insulated frames can help retain heat.
⚠️ Potential Drawbacks
Poorly insulated or single-glazed skylights can significantly increase heat loss.
Large skylight areas may contribute to overheating in summer, increasing cooling demand.
Incorrect installation or air leakage around skylights often lowers EPC performance.
Strategies to Improve EPC with Roof Angles & Skylights
Upgrade Skylight Glazing: Use double or triple glazing with low-E coatings.
Seal Air Gaps: Ensure skylights are properly fitted with insulated frames.
Add Roof Insulation: Focus on insulating around awkward roof spaces to reduce heat loss.
Consider Solar Control Glass: Helps balance light benefits while minimising overheating.
Work with Accredited Assessors: An expert EPC assessor will correctly account for roof design and skylight efficiency.
👉 For expert guidance, check our Residential EPC services.
Fast and Affordable EPC Solutions
Whether your property has a simple pitched roof or a complex design with skylights, Urgent EPC provides:
Same-Day EPCs for urgent transactions.
Transparent pricing plans starting from just £59.
Accredited assessments tailored to unique property features.
Need advice? Get in touch today via our Contact Us page.
Final Thoughts
Non-standard roof angles and skylights may enhance your property’s appearance and natural light, but they can also influence your EPC rating more than many owners realise. By ensuring proper insulation, high-quality glazing, and professional assessment, you can balance design with efficiency — and protect your property’s long-term value.
