As of June 15, 2025, a major overhaul of the Energy Performance Certificate (EPC) system took effect. The new methodology, known as RdSAP 10, marks the most significant change in over a decade to how domestic energy efficiency is assessed. For landlords and property investors, this is not just an administrative update; it is a strategic shift with direct implications for compliance, costs, and property value.

What is changing?

RdSAP 10 introduces a more detailed and evidence-based approach to assessing the energy performance of residential properties. The updates are designed to better reflect modern building technologies and real-world energy use. Key changes include:

• Assessors must now record specific information about windows, insulation, and ventilation.
• Improvements such as double glazing or new boilers will only be factored into the EPC rating if they are supported by relevant documentation, including invoices, warranties, or certificates.
• Solar panels, battery storage and smart heating controls are now included in EPC calculations.
• Manufacturer data and model numbers are used instead of default assumptions, which benefits properties with modern or electric systems.
• Flats and mid-terrace homes may now receive better EPC ratings due to improved heat loss modelling.

What does this mean for landlords?

The impact of these changes is significant and multi-layered; we have listed some areas that you need to consider as a landlord of property investor.

Documentation is now essential.

Without proper records, energy improvements will not be reflected in the EPC, even if the work has been done. This could lower a property's rating and affect its legal requirements as rented accommodation.

Assessment costs may rise.

More detailed inspections will take longer, typically an additional 20 to 30 minutes. This may reduce the number of appointments assessors can handle daily and increase their fees.

Compliance is tighter.

With EPC minimum ratings for rental properties likely to rise to C by 2028–2030, a lower rating caused by missing paperwork could hinder a landlord's ability to let or sell a property.

Portfolio planning needs to evolve.

Investors must think strategically about upgrades, focusing on measures that are verifiable and improve energy performance. This could also influence access to green finance and retrofit funding.

Positive changes for some property types.

Flats and mid-terrace homes, which were previously disadvantaged under the old system, may now score more favourably.

What should landlords do now?

Landlords are not required to update their current EPCs until they expire. However, from 15 June 2025, any new or renewed certificate will be produced using the new methodology. It is therefore wise to start preparing immediately.

• Audit and organise documentation for all energy improvements.
• Consider pre-assessment surveys to understand the current state of your properties.
• Stay informed about minimum EPC standards and funding opportunities.

At Watson Knipe, we work with landlords and property investors, helping them to manage their property portfolio more efficiently. For more information, please visit our Advice for Landlords page.