Why has my EPC dropped from C to D?
A new certificate can be lower than the one before it for entirely legitimate reasons. Here are the common causes, and how to tell whether something genuinely deserves another look.
Why a new certificate can be lower than the last one
It is one of the most common questions we are asked: nothing has been taken out of the property, yet the new certificate is a band lower than the one before it. In most cases there is a straightforward explanation, and it is rarely as simple as one assessor being right and the other wrong.
1. Evidence available on the day
Insulation that cannot be seen or evidenced cannot be recorded as present. If a previous assessment was able to rely on paperwork that was not available at the later visit, the same element may be recorded differently and the score changes accordingly.
2. Methodology updates
The approved methodology (RdSAP) is revised over time, including how particular elements, fuels and heating controls are treated. Two assessments carried out under different versions of the methodology can produce different results for an unchanged property.
3. Changes to the property or its systems
A replacement boiler, a change of fuel, removed or disturbed insulation, a new extension, converted loft space or altered heating controls can all move a rating in either direction.
4. Different recorded property data
Floor area, property type, wall construction, glazing proportion and room heights all feed the calculation. A difference in any of these between two assessments will change the outcome, and one of them may simply be more accurate than the other.
5. Default assumptions
Where evidence is unavailable, the methodology requires cautious default assumptions. These are not errors — but they can understate a property that has genuinely been improved.
How to tell whether something deserves another look
- Compare the two certificates element by element, not band to band.
- Note every element where the descriptions differ.
- Check which version matches the property as it stands today.
- Collect the paperwork that proves the improvements you know were carried out.
If several elements differ and the older certificate matches the property better, that is worth investigating. If the differences are limited to assumptions where you hold no evidence, a new assessment supported by that evidence is usually the more productive route.
How D8 can help
D8 can compare your current and previous certificates, review the recorded property data against the evidence you hold and explain what appears to have changed and why. Think your EPC may not be right? Start with a free initial consultation by phone, email or WhatsApp.