Achieving higher EPC ratings: what gets measured gets improved

June 6, 2022 6 Minute Read

By Mark Rahim


Not least because of the regulatory pressure created by the Minimum Energy Efficiency Standards (MEES), we at CBRE are now regularly being asked how much it will cost to improve a building’s energy efficiency to a point where it can enjoy the higher EPC rating which MEES requires – an ‘E’ rating for now, but a ‘B’ rating by 2030.

But working out how much it will cost to achieve these higher ratings is rather like the proverbial question, ‘how long is a piece of string?’

The answer is: measure it.

EPC ratings are created using assessment software which takes many separate inputs and converts these into a score, and the score is then converted into the rating (A to G). When asked to advise on what combination of measures is likely to be most effective, we typically make four suggestions.

Firstly, look at the recommendations on the EPC. There always are some, and while these recommendations are blind to both costs and the carbon emissions of implementing them, they do form a useful starting point as to what the software itself says is likely to be most effective. However, we find that the default software recommendations are often unfeasible or obsolete; so at CBRE we aim to add value for clients by making our own bespoke recommendations.

Secondly, don’t skimp on the EPC assessment in the first place. We think it is almost always a false economy to constrain an EPC assessment to the minimum necessary. This is because EPC conventions assign pessimistic default assumptions in the absence of any data to the contrary. So a lightweight assessment in which the EPC assessor has not gone digging for any measurements or technical data to replace the default scores is typically going to result in a lower score than would otherwise be the case.

An example is air tightness. CIBSE have suggested that up to 30% of heat loss in buildings is due to air infiltration. If so, then commissioning an air pressure test as part of the EPC assessment will quickly indicate how exposed the building is to that problem, although this may not be practical in every case. Similarly, knowing the date of manufacture of any post-construction boiler replacement can be very helpful.

More generally, the quality and precision of the recommendations is dependent on the quality of the underlying data. Landlords can assist this process by collating the full range of operation and maintenance manuals, design specifications, commissioning data, and manufacturers literature. These sources are a goldmine of useful EPC data. If they are not available, the technical data is often impossible to identify, and the suboptimal defaults become unavoidable.

Thirdly, remember that the inputs are interrelated and complimentary, so it’s often a combination of measures that improves the score. Some measures, even if worthy, will do very little, especially if implemented on their own.

Fourthly, an estimate is always better than a guess. The best way to develop a strategy to improve a building, either for an improvement to the EPC or the operational energy usage, is to use modelling and simulation. We find this provides a measured and quantifiable solution, even if only indicative and at risk of updates to the regulations and conventions.

Finally, although the usual suspects of lighting, glazing, and insulation are almost always worth considering, there are often more obscure factors in the EPC assessment calculation where doing nothing about the default value can be quite damaging to the score (for example, power factors, which if corrected can improve the EPC score).

In fact, we typically turn the question “how much will it cost?” around and ask instead: “how much are you able to spend now?” This is because most improvements will pay back eventually through energy bill savings. So the question of which improvements are worthwhile is just about how lengthy a custodian of the building our client expects to be, and what their strategy for their real estate is in the first place, as my colleague Jenni Dobbs wrote here. At CBRE we review the building’s occupancy, lease events and service charges to develop a Sustainable Asset Improvement Plan in order to map out and estimate investment requirement.

Admittedly it can be difficult to identify the payback period for any individual measure, although again accurate baseline data will help. And it’s tempting to wait, to see if technological improvements might achieve the same emissions reductions for less cost in future. But waiting is not a cost-free option. For example, a surge of refurbishments as the 2030 MEES deadline approaches could result in significant cost price inflation.

Overall, therefore, a combination of diligent assessment and measurement, assessment of options in combination, and a budget aligned to the building owner’s hold strategy, can start to make it clear what needs to be done. One thing’s for certain: with a regulatory deadline in prospect, ignorance is not bliss.