Many homeowners are shocked when their Energy Performance Certificate shows a lower-than-expected rating, even though their property feels warm, efficient, and upgraded.
The truth is: EPC scores don’t always align with your real-world experience—because the assessment follows strict rules, documented evidence, and measured assumptions.

If your energy-efficient home still scored poorly, here are the real reasons behind the mismatch and how to fix them before your next assessment.

1. Your Upgrades Aren’t Counted Without Proof

Even if you’ve installed insulation, new glazing, or modern heating systems, an assessor cannot include them unless proof is available.

Common missing documents include:

  • Cavity wall insulation certificates

  • Loft insulation installation proof

  • Double-glazing documentation

  • Solar PV certification (MCS)

  • Boiler installation paperwork

Without this, assessors must assume your home has the lowest standard for that element.

To avoid this problem, review documentation requirements and pricing beforehand:
➡ EPC Pricing

2. EPCs Use Standardised Assumptions—Not Real-Life Usage

EPC methodology doesn’t measure your actual energy bills or lifestyle choices.
It assumes how the “average household” uses energy, which may not match your habits.

So even if you:

  • Heat rooms selectively

  • Use energy-efficient appliances

  • Monitor heating through a smart thermostat

…your EPC score won’t reflect these behaviours.

3. Some Renovations Lower Efficiency Without You Realising

Home improvements sometimes make houses look better but perform worse.

Examples assessors frequently see:

  • Loft conversions with thin insulation

  • Extensions without proper cavity insulation

  • Conservatories that lose heat rapidly

  • Uninsulated steel beams creating cold bridges

If you’ve renovated recently, an expert check may help:
➡ EPC Assessors London

4. Heating Controls Matter More Than Many Homeowners Expect

Even with a modern, efficient boiler, your EPC rating can drop sharply if:

  • Radiator TRVs are missing

  • Thermostat is outdated or badly positioned

  • Programmer isn’t functioning

  • No smart heating controls are installed

Heating controls form a major part of the EPC scoring system.

Booking an assessment with guidance on improvements can help:
➡ Book EPC Online

5. EPCs Don’t Consider Newer Technologies Yet

Some modern energy-saving technologies aren’t fully recognised in the EPC calculation.

Examples include:

  • Infrared heating panels

  • Certain heat pump models

  • New insulation materials

  • Hybrid solar technologies

Even if they improve real comfort and efficiency, they may not significantly lift your EPC score.

6. Hidden Heat Loss Areas You Can’t See

Homes often have unseen problems that drag down the EPC, such as:

  • Slumped cavity wall insulation

  • Damp or compressed loft insulation

  • Draughts under floorboards

  • Air leaks around doors and extensions

These issues are usually invisible until an assessor inspects the property.

7. EPC Ratings Are Compared to Modern Standards

Older homes often feel efficient after upgrades, but EPC rules compare them to current building regulations—not to similar homes of their age.

So even with good improvements, your home may still fall short of modern new-build standards.

How to Improve an EPC Score That Doesn’t Reflect Reality

Here’s what you can do:

✔ Gather all installation documentation

✔ Add or top-up insulation

✔ Install smart heating controls

✔ Fix draughts and cold bridges

✔ Upgrade windows or glazing if necessary

✔ Book a re-assessment after improvements

Need help from a qualified assessor?
➡ EPC Assessors London
➡ Contact Our EPC Team

Email :info@epcrate.co.uk

Phone:020 34884142