As of 15 June 2025, a major update to Energy Performance Certificates (EPCs) is now in effect.

The new methodology, known as RdSAP 10, changes how a property’s energy efficiency is assessed, and it may affect your rental income, mortgage eligibility, and future investment plans.

What’s new under RdSAP 10?

EPCs are now based on a more detailed and evidence-driven system. RdSAP 10 replaces older assumptions with real data about your property, making the results more accurate but also more demanding.

Assessors now look more closely at:

• The type and condition of glazing
• Insulation and how it was installed
• Heating system efficiency (based on model-specific data)
• Smart heating controls
• Use of LED and low-energy lighting
• Floor layout and building structure

These changes mean EPC ratings may now differ from previous assessments, particularly where improvements were made but not documented.

Your EPC rating could drop, even if you’ve upgraded

The legal minimum EPC rating for rental properties is still E (unless exempt), but this new system may make it harder to reach that standard, even if you have made energy improvements.

That is because only documented improvements now count.

No evidence, no rating. How missing paperwork can reduce your EPC score

This is one of the most important changes under RdSAP 10.

If you have installed cavity wall insulation, replaced windows, or upgraded the boiler, but cannot provide receipts, invoices, or certificates, then the system may assume that the original features are still in place.

For example:

• Had double glazing installed five years ago but have lost the invoice? It might not appear in your EPC.
• Upgraded your boiler but lost the paperwork? The rating could reflect a less efficient system.

To get the credit you deserve in your EPC, you need to show clear evidence of the work that’s been done.

A downgraded EPC rating could affect the property’s rental income, market value, or even access to favourable mortgage rates or green finance incentives, so documenting upgrades is now just as important as carrying them out.

If your EPC was issued before 15 June 2025, it will still be valid for 10 years from the date of issue, even if it was based on the old methodology.

This may be worth considering if your current certificate is due to expire soon.

What landlords and investors should do now

With the new EPC rules now in force, landlords should take practical steps to protect their property ratings and ensure ongoing compliance.

Review your current EPCs

If your property had a strong rating under the old system, check whether that still holds under the new one. You might want to update your EPC or gather evidence before renewing.

Collect your documents

Make sure you have clear, dated paperwork for any improvements, past or present.

That includes installation certificates, invoices, receipts, warranties, and product specs.

Plan ahead for future works

Going forward, keep records of all work done and file them safely.

Without proof, future assessments may not reflect the real condition of your property.

We can help you plan ahead and make sure you are not caught out by changes that affect your bottom line.

If you are unsure how these changes might affect the value or income from your rental properties, or you’ve noticed a drop in your EPC rating, speak to us today.