How to improve a commercial EPC rating
Updated 23 October 2026 · SEO Dons Editorial
There is no single lever for a commercial EPC. The certificate is the output of a model, so the rating moves when the inputs to that model move: what the building is made of, how each zone is used, what services heat, cool, ventilate and light it, and how those services are controlled. This guide explains how the score is built, where to look first, and how to order works around MEES. The deeper guides on lighting, heating and cooling controls and an F or G rating take over from there.
How is a commercial rating scored, in brief?
Against a reference building. The government guide says the calculation compares the carbon emissions of the building with those of a reference building: an equivalent building of the same size, shape and use, constructed to a notional building designed to a specified standard. The NCM website describes the notional building in the same terms and adds that its U-values and building services efficiencies are specified values.
The tool for most buildings is SBEM, which estimates monthly energy use and carbon dioxide emissions from a description of the building’s geometry, construction and services, under standardised operating conditions. The arithmetic that turns the comparison into a score and band is in the SBEM Technical Manual rather than the guide. What matters in practice is that the activity parameters cannot be changed by the user. So the rating moves when the described building changes, not when the model’s assumptions do, and how commercial EPC ratings are worked out covers the method in more detail.
Which parts of the building does the rating respond to?
The guide says the energy rating “is a complex calculation which is based on a combination of factors”, and lists what the assessor gathers. The table maps each input to what is recorded.
| Input | What the assessor records | Read next |
|---|---|---|
| Fabric | The construction of the fabric and the thermal efficiency of the materials: roof, floors, walls and glazing | This page |
| Zones and use | The activities conducted in each zone, such as retail space, office space, kitchens or storage, each with a standard occupancy pattern | EPCs and change of use |
| Heating, cooling and ventilation | For each zone, the type of system, metering, controls and fuel used | Heating and cooling controls |
| Hot water | The system and, where known, the storage volume and insulation; otherwise defaults are used | Below |
| Fans, pumps and controls | Auxiliary energy, which depends on the system type and information such as specific fan power, leakage and control provision | Below |
| Lighting and controls | The lighting and controls used for each zone | LED lighting |
No source read for this guide ranks these inputs, and the NCM website warns against assuming one. In some non-domestic buildings heating is responsible for only a small proportion of the total carbon dioxide emissions compared with, for example, lighting. Further insulation in such a building would have a limited effect and may, where cooling is provided, increase the calculated emissions. The guide also says the calculation deducts any energy generated by technology installed in the building. Generation and low-carbon heating can therefore appear in a report like any other measure, and choosing between them is outside this guide.
Where should you start?
With the certificate and its recommendation report, not with a shopping list. The guide says recommendations are grouped by payback: short term (less than 3 years), medium term (3 to 7 years), long term (more than 7 years), plus other recommendations from the assessor’s own knowledge. It adds that they include only improvements appropriate for the building assessed, with indicative paybacks noted. There is no statutory requirement to carry out any of them. How to read a commercial EPC recommendation report goes through the layout.
- Check the data first. If the report recommends something the building already has, an input may have been missed. What to do if your commercial EPC looks wrong sets out the route.
- Sort by payback and by timing. Short-payback items, such as controls, can often be done without waiting for a larger project. Items that need plant replacement or a vacant floor belong in a capital plan.
- Price the shortlist. The report gives paybacks, not prices, so use installers’ quotations.
- Find out who must consent. The landlord guidance lists tenants, superior landlords, mortgagees, freeholders and planning departments as parties whose consent some improvements need.
- Look for funding. The funding page sets out what applies to the works, as distinct from the certificate.
Can better evidence change the result without works?
Sometimes the gap is paperwork rather than plant. The NCM website says the software defaults “are conservative values, more representative of existing rather than new buildings” and should be used only if the data is not available. Its hot water example is specific: with no storage data entered, the defaults “assume, for example, that the storage tank is poorly insulated”, and it recommends that users enter the actual storage data.
That does not mean evidence alone will change a band. It means an assessor can only credit what can be shown, so installation records, data sheets and commissioning papers have a value of their own. The lighting and controls guides cover what each assessor needs to see.
Why do you need a new EPC to show an improvement?
Because the register does not update itself. The guide says once EPCs have been registered they cannot be altered, and that where other certificates for the building are less than 10 years old only the most recent is valid. Regulation 9 says the same: a certificate stops being valid for the purposes of the Regulations if another has since been entered on the register.
The guide also says that where accommodation has been renovated, for example with upgraded heating, it would be preferable to have an updated EPC even though one is not required. Plan the reassessment as the last step: finish the works, assemble the evidence, then ask for quotes through this site’s form. A new certificate replaces the old one whichever way the result moves, so check the evidence before it is lodged.
How should you sequence works for MEES and the proposed EPC B?
Three things set the order. First, the current test. For a covered letting, a property is sub-standard where its valid EPC is below band E, and the landlord must not let it unless an exemption applies. Most fixed lettings of six months or less and leases of 99 years or more are outside the rule: MEES compliance sets out the scope.
Second, the link to the report. Regulation 28 counts an energy efficiency improvement as relevant only if, among other tests, it has been identified as a recommended improvement in a green deal report, a recommendation report or a surveyor’s report. For Table 6 measures from Approved Document L2B, it treats them as relevant where they would achieve a simple payback of seven years or less. The landlord guidance puts the aim this way: “every property is undertaking improvements to achieve the highest EPC rating that a cost-effective package of measures can deliver”.
Third, the proposal. The government’s interim response of 18 June 2026 proposes that from 2031 private rented buildings over 1,000 square metres in England and Wales reach EPC B, where cost effective. It is not law until secondary legislation is passed. Buildings below 1,000 square metres are intended to stay at EPC E, the 2027 EPC C milestone will not be taken forward, and the 7-year payback test and exemptions remain. The response says the extra time is to let landlords and tenants improve “in a way that suits their buildings and lease agreements”. EPC B by 2031 explains who it would catch.
A planning sequence, using a hypothetical example: a privately let office building of 1,500 square metres with a certificate nearing the end of its 10 years.
| Stage | Action | Why |
|---|---|---|
| Now | Read the rating and valid-until date; check the data against the building | The band E test uses the valid EPC |
| Before the next lease event | Sort the report by payback; identify measures that need consent | Consent can decide what is achievable |
| When space or plant becomes available | Fold report measures into planned works; keep installation evidence | The assessor can credit only what is evidenced |
| After the works | Commission a new EPC | The improvement shows only once it is lodged |
| Before 2031, if the proposal is enacted | Review the building against the final rules and threshold | Over 1,000 square metres and privately rented is the proposed scope |
This sequence promises no particular band. The report’s measures are the starting list and the building decides the result.
Sources
- A guide to Energy Performance Certificates for the construction, sale and let of non-dwellings, Ministry of Housing, Communities and Local Government (GOV.UK) (11 December 2017), checked 22 October 2026.
- UK's National Calculation Method for Non Domestic Buildings (NCM and SBEM introduction), uk-ncm.org.uk (BRE, official NCM and SBEM website), checked 22 October 2026.
- NCM and SBEM frequently asked questions, uk-ncm.org.uk (BRE, official NCM and SBEM website), checked 22 October 2026.
- Technical annex for chapter 2: What EPCs measure, Ministry of Housing, Communities and Local Government and Department for Energy Security and Net Zero (GOV.UK) (9 March 2026), checked 22 October 2026.
- Non-domestic private rented property: minimum energy efficiency standard, landlord guidance, Department for Energy Security and Net Zero (GOV.UK) (5 May 2026), checked 22 October 2026.
- Minimum Energy Efficiency Standards (MEES) in the non-domestic Private Rented Sector: interim response, Department for Energy Security and Net Zero (GOV.UK) (18 June 2026), checked 22 October 2026.
- Energy Performance of Buildings (England and Wales) Regulations 2012 (SI 2012/3118): regulations 9, legislation.gov.uk (The National Archives), checked 22 October 2026.
- Energy Efficiency (Private Rented Property) (England and Wales) Regulations 2015 (SI 2015/962): regulations 20, 22, 27 and 28, legislation.gov.uk (The National Archives), checked 22 October 2026.
Common questions
Do I have to carry out every measure in the recommendation report?
No. The government guide says there is no statutory requirement to carry out any of the recommended measures. For MEES, regulation 28 defines which improvements count as relevant, and the 7-year payback test and exemptions remain in place.
Does a better score on a new EPC replace the old one?
Yes. Only the most recent certificate on the register is valid, whether its result is better or worse. A new certificate replaces the old one for the purposes of the Regulations once it is entered on the register.
Do buildings under 1,000 square metres need to go beyond band E?
Not under the current proposal. The interim response says buildings below 1,000 square metres are intended to stay at EPC E. That proposal is not yet law.
Is there a standard package of works that gets a building to band E?
No source reviewed gives one. The guide says recommendations include only improvements appropriate for the building assessed, so the package depends on the building and its certificate.