When homeowners or landlords receive their Energy Performance Certificate (EPC), the result often comes as a shock. Properties that seem “energy efficient” sometimes score poorly, while older buildings occasionally perform better than expected. So, why do these surprises happen? Let’s uncover the EPC secrets that can influence your property’s rating.
1. EPCs Focus on Theoretical Performance, Not Real Bills
An EPC doesn’t measure your actual energy usage or monthly bills—it calculates the potential efficiency of your property based on construction, insulation, heating systems, and lighting. That means even if your bills are low due to frugal habits, your EPC rating may still be poor if the building fabric isn’t up to standard.
2. Insulation Matters More Than You Think
Loft, cavity wall, and floor insulation have a huge impact on EPC scores. A well-heated home with poor insulation loses points quickly, while an older property that has been retrofitted with insulation can leapfrog newer homes.
3. Heating Systems Can Make or Break Your Rating
Outdated boilers, inefficient electric heaters, or lack of thermostatic controls drag EPC scores down. On the flip side, modern condensing boilers, heat pumps, or underfloor heating systems can dramatically improve results.
4. Lighting Plays a Bigger Role Than Expected
It may sound trivial, but switching from halogen bulbs to LED lighting can add a surprising boost to your rating. EPC assessors look at every energy-saving measure, even small ones.
5. Windows and Air Leakage Are Hidden Culprits
Single-glazed or draughty windows can slash your EPC score. Sometimes, even newer double glazing underperforms if poorly installed, letting cold air seep in and reducing the theoretical efficiency.
6. Renewable Energy Isn’t Always a Guaranteed Win
Installing solar panels or wind turbines can improve your EPC, but the gain depends on system size, orientation, and integration with existing heating systems. Poorly sized or inefficient installations may not add as much benefit as expected.
7. Age of Property Isn’t Everything
Many owners assume modern homes always score higher, but that’s not always true. Some new builds cut corners with cheap insulation or poor ventilation. Meanwhile, older properties with energy upgrades—such as solid wall insulation—sometimes outperform them.
8. Software Assumptions Can Skew Results
EPC ratings are generated using government-approved software, which makes assumptions about construction materials, heating demand, and insulation thickness. These assumptions don’t always reflect the true performance of your home, leading to unexpected EPC outcomes.
Why This Matters for You
Whether you’re a homeowner looking to improve efficiency, a landlord preparing for rental regulations, or a seller aiming for a better market value, knowing these EPC secrets helps you plan upgrades strategically.
📌 Tip: Even small, affordable improvements—like switching to LEDs or sealing draughts—can push your property into a higher band, potentially saving you money and increasing property value.
Need an EPC Fast?
At Urgent EPC, we provide same-day EPCs across London with clear, practical advice on how to improve your score. Whether it’s for a sale, rental, or compliance, we’ll help you uncover the true potential of your property.
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