How to Improve Your EPC Rating

House alongside an EPC rating scale showing an improvement towards a higher energy efficiency rating

The current methodology for EPC assessments of existing dwellings in England and Wales is RdSAP 10. The Government plans to introduce reformed EPCs based on the Home Energy Model (HEM) in the second half of 2027.

Changes to EPC metrics will also affect how property energy performance is reported and how future Minimum Energy Efficiency Standards (MEES) are assessed. For privately rented homes in England and Wales, the Government has set 1 October 2030 as the compliance date for the new MEES standard.

These changes mean that the measures needed to improve a property's current EPC rating may not necessarily be the same as those required to meet future standards. The guidance on this page relates primarily to the current RdSAP methodology.

Introduction

I'd like to help you achieve the best EPC rating your property can reasonably attain.

Improving an Energy Performance Certificate (EPC) rating isn't simply a matter of installing the latest energy-saving technology. The improvement you can achieve depends on the property's construction, insulation, heating system and other characteristics, as well as how these features are assessed under the current EPC methodology.

Some improvements can make a significant difference to an EPC rating, while others may have a surprisingly small effect. In some cases, checking an existing EPC for errors or providing suitable documentary evidence for insulation and other features can be just as important as carrying out physical improvements.

This guide explains the main ways to improve an EPC rating, how to identify potential improvements and why it's worth understanding their likely effect on your property's rating before committing to major expenditure.

What Can Improve An EPC Rating?

The current EPC Energy Efficiency Rating (EER) is a cost-based measure of a property's modelled energy performance. The assessment estimates energy costs under standardised conditions, taking account of factors including space heating, water heating, lighting and the thermal characteristics of the building.

Improvements that reduce the modelled energy costs can increase the EPC rating, but their effect depends on the property's existing characteristics and how the proposed changes are represented in the assessment methodology.

The main areas to consider are as follows.

Building Fabric

Reducing heat loss through the building fabric can reduce the energy needed to heat a property. Relevant features include walls, floors, roofs, windows and doors.

Insulation, improved glazing and other fabric improvements can affect the assessment, depending on the property's existing construction and the measures undertaken.

U-values are used to represent the thermal transmittance of building elements.

Heating Systems

The type and efficiency of the heating system, the fuel used and the associated controls can influence the calculated EPC rating.

Depending on the existing installation, improvements might involve upgrading the heating system, changing to another type of heating or improving the way the existing system operates.

The effect of a proposed change should be assessed for the individual property rather than assumed in advance.

Lighting and Ventilation

The type and efficiency of fixed lighting can affect the EPC rating. Ventilation characteristics also influence the assessment of heat loss and energy demand.

Where suitable air-pressure test results are available, these may be relevant to the assessment under the current methodology. However, carrying out a test does not itself guarantee an improvement in the rating.

Renewables

Technologies recognised by the current methodology include solar photovoltaic panels, solar thermal panels, PV diverters, PV batteries and wind turbines.

Their effect on the EPC rating depends on the technology installed and how it is represented in the assessment. Not every renewable-energy installation will produce the same improvement.

Other Things You Might Not Have Considered

There are several other ways to investigate whether an EPC rating could be improved:

Products Characteristics Database (PCDB): check relevant product information where the methodology requires or permits it.
EPC errors: identify possible mistakes in the existing assessment.
Documentary evidence: establish whether suitable evidence supports features that may otherwise be recorded using assumptions.
EPC assessment data: review the data recorded for the property.
Understanding the methodology: learn how the assessment works and which features can influence the rating.

The effect of any proposed change should be considered in the context of the applicable assessment methodology.

How To Improve An EPC Rating From D to C

When considering how to improve an EPC rating, it's important to look at the numerical score as well as the band.

Under the current Energy Efficiency Rating scale, band C starts at 69. A property with a score of 68 is therefore in a very different position from one scoring 55, even though both properties are in band D.

The improvements needed to reach band C will depend on the property's starting score and characteristics.

If your property is already at the top of band D, there are several important points to consider.

The numerical score matters. The calculated rating is rounded to the nearest integer for presentation on the EPC. The underlying calculation retains greater precision.
EPC recommendations are prescribed by the methodology. Only recommendations defined by the applicable methodology can appear on the certificate.
Recommendations have minimum thresholds. Under RdSAP 10, a recommendation generally needs to produce an improvement of at least one SAP point to appear. The threshold is 0.5 SAP points for low-energy lighting, hot-water cylinder insulation and draught-proofing, subject to the applicable rules.
Other changes may also improve the rating. Not every change that affects the calculation will necessarily appear as a recommendation on the EPC.
Several small improvements can add up. Individual measures may produce fractional improvements which, when combined, can move the final rating into the next band.

The important point is that you shouldn't assume you need to undertake a major improvement simply because your property is in band D. Equally, a property with a lower D rating may require more substantial work to reach band C.

The best approach is to identify which improvements are relevant to the property and assess their likely combined effect.

This is why there is no single list of improvements that will take every band D property to band C.

Before You Spend Money...

Before spending thousands of pounds on energy improvements, it's worth understanding how the proposed work is likely to affect the EPC calculation.

Expensive improvements don't necessarily produce the greatest increase in an EPC rating. The most appropriate measures will depend on the property's existing characteristics, the current assessment methodology and the outcome you're trying to achieve.

If you're a landlord seeking to comply with Minimum Energy Efficiency Standards (MEES), you should also understand the applicable requirements and any exemptions for which the property may qualify. An exemption should never be assumed to apply without checking the relevant conditions.

The best approach is to consider the individual property and, where appropriate, ask a suitably qualified Domestic Energy Assessor (DEA) to model potential improvements before committing to major work.

This can help you understand the likely effect of different options and avoid spending money on measures that don't deliver the outcome you expected.

Explore Our Detailed EPC Improvement Guides

Building Fabric and Construction

Heating Systems

Lighting & Ventilation

Renewables

EPC Assessment and Other Guides

Real-World Case Studies

Every property is different, and the improvements that make the biggest difference to one home may not have the same effect on another.

Our case studies examine real properties, their original EPC ratings and the changes that helped improve their assessed energy performance.

Explore the examples to see how different construction types, insulation measures and heating systems can affect EPC results.

View our EPC improvement case studies