Mixed-Use Premises: commercial EPC assessment

Mixed-use EPCs: when you need one

A mixed-use EPC is what a classic high-street building needs — a shop or office below with flats above — and the single most important thing to understand is that a mixed-use building does not have one EPC. The commercial floor needs a non-domestic EPC and each flat needs its own domestic EPC. Getting that split right is the most common source of confusion for mixed-use owners, and getting it wrong leaves you with invalid or missing certificates at exactly the point a sale or letting depends on them.

You need the relevant certificate whenever you sell, let or construct any part of the building in England or Wales. In practice that means: selling or letting the commercial ground floor triggers a non-domestic EPC for that unit; letting a flat triggers a domestic EPC for that flat; selling the whole building triggers certificates for every let-able part. Each EPC rates its part from A to G and lists the improvements that would raise the score, and each is what the relevant buyer’s or tenant’s solicitor asks for before completion. Every EPC — commercial or domestic — is valid for ten years from lodgement, and one current certificate covers repeated lettings of that part inside the window.

A worked example makes the split concrete. Take the most common mixed-use building of all: a ground-floor shop with two self-contained flats above, all let. That building needs three separate certificates — one non-domestic EPC for the shop, and one domestic EPC for each of the two flats. If only the shop is let and the flats sit empty and owner-occupied, you need just the one non-domestic certificate for now, with a domestic EPC required for each flat the moment it is sold or let. The rule is simply that every part you sell, let or construct needs its own certificate of the correct type.

The reassuring feature of mixed-use is that a single freehold owner often controls the whole building, which simplifies improvement works and means the certificates and any upgrades can be planned together rather than negotiated between separate owners.

What drives a mixed-use building’s rating

Because a mixed-use building is assessed as separate parts, each part is rated on its own fabric and services — and the two assessments use entirely different methods.

• The commercial floor is assessed under the Simplified Building Energy Model (SBEM) by a Non-Domestic Energy Assessor, looking at the shopfront or glazing, heating, any cooling and ventilation, lighting and controls for that unit. A high-street commercial unit typically has the same weak points as any shop or small office — an open or single-glazed shopfront, older heating, dated lighting.
• Each flat is assessed under RdSAP by a Domestic Energy Assessor, looking at the dwelling’s walls, roof, windows, heating system, hot water and controls. A flat above a shop is rated like any other dwelling.

The shared shell can create quirks the assessments handle separately: heat rising from a heated ground-floor unit, a flat over an unheated or cold commercial space, and party constructions between the two. But there is no single combined rating — the commercial part gets a commercial rating and each flat gets its own. That is also why the fabric of one part can matter to another in practice, even though the certificates are distinct, and why a single freehold owner is well placed to improve the whole envelope coherently.

Assessment level and what it costs

Mixed-use pricing has two components, because there are two kinds of assessment.

• The commercial floor is priced like any small commercial unit: SBEM Level 3 for a simple, single-zone shop or office suite (broadly under 250 square metres, simple services), or SBEM Level 4 if it is larger, multi-zone or more heavily serviced. A correction worth making, because it is muddled online: DSM is Level 5, and a Level 4 assessment is still SBEM — though DSM is very unlikely for a small high-street commercial floor. Our guide to SBEM Level 3 vs Level 4 vs DSM explains the levels.
• Each flat is a separate domestic EPC (RdSAP), priced per dwelling.

The £200 to £700 plus VAT range shown here is for the commercial element only — the non-domestic EPC on the commercial floor. Each domestic EPC for a flat is a separate, additional cost per flat. The commercial fee is driven by floor area, the number of heating and cooling systems, the number of zones and site access; the domestic fees by the number and size of the flats. Where a single owner needs the commercial EPC and several flat EPCs on one building, arranging them together is usually the most efficient approach. Our commercial EPC cost guide sets out the commercial ranges, and the honest total for a specific building follows once the split — how many separate certificates the building actually needs — is established.

MEES and your mixed-use building

Mixed-use is where two MEES regimes overlap in one building, and they run on separate tracks. The non-domestic standard governs the commercial floor; a separate domestic standard governs each let flat. An owner has to satisfy both.

For the commercial floor, the current minimum to let is EPC E, and since 1 April 2023 it has been unlawful to continue letting a commercial unit rated below E, not just to grant a new lease. An F or G commercial floor cannot lawfully be let or continue to be let without a valid exemption on the PRS Exemptions Register. Non-domestic MEES penalties are tiered on rateable value and the length of the breach, up to a maximum of £150,000 per property, with public naming of non-compliant landlords, and failing to have or provide a valid EPC on a sale or let carries a separate £500 to £5,000 penalty.

For the flats, the domestic private-rented minimum is also EPC E, but the domestic and non-domestic regimes are legally distinct, with their own rules, exemptions and timelines — which is exactly why the two parts must be assessed and complied with separately. Our guide to commercial vs domestic EPCs sets out how the two differ and why using the wrong type is a costly mistake.

The tightening standard applies to the commercial part by floor area. On 18 June 2026 the government confirmed that, subject to secondary legislation, privately rented non-domestic buildings over 1,000 square metres are proposed to reach EPC B by 2031, with the interim EPC C milestone for 2027 dropped. Most high-street commercial floors are well under 1,000 sqm and stay on the EPC E minimum, but a large commercial element over the threshold is caught. Our guide to EPC B by 2031 and commercial MEES covers where the line falls, and the government’s interim response on EPC B by 2031{rel=“noopener”} confirms the position.

Improving a mixed-use building’s rating

The EPC reports — one for the commercial floor, one per flat — each list recommended improvements ranked by impact, and a single freehold owner can plan them coherently across the building. The realistic levers are these.

• Commercial floor: LED lighting and heating controls. As with any shop or small office, replacing dated lighting with LED and improving heating controls are the cheapest, highest-value measures to clear or comfortably exceed the E line.
• Commercial floor: shopfront and heating upgrades. Draught-proofing an open shopfront and upgrading carbon-heavy electric heating raise the commercial rating further where a longer commercial lease justifies it.
• Flats: heating, insulation and controls. Domestic improvements — efficient heating, loft or wall insulation where the construction allows, and better heating controls — lift each flat’s rating.
• Whole-envelope measures a single owner can coordinate. Where one owner controls the freehold, roof insulation, low-carbon heating and fabric upgrades can be sequenced across the whole building, benefiting both the commercial and residential parts in one programme rather than piecemeal.

The practical route is to commission the correct certificates first — the non-domestic EPC and each domestic EPC — read each recommendation report, and target the measures with the best rating uplift per pound. Because a single owner often controls the lot, mixed-use is one of the easier cases in which to plan improvements against both MEES regimes at once.

Mixed-use EPC — common questions

Does a shop with flats above need one EPC or several? Several. The commercial floor needs its own non-domestic EPC, and each flat needs its own domestic EPC — there is no single combined certificate for a mixed-use building. So a shop with two flats above needs three certificates in total when all parts are let: one non-domestic and two domestic. This is the single most common area of confusion for mixed-use owners, and getting the count right is what keeps every part lawfully let-able.

Can one assessor do the whole mixed-use building? Only if they hold both accreditations. The commercial floor must be assessed by an accredited Non-Domestic Energy Assessor using SBEM, and each flat by a Domestic Energy Assessor using RdSAP — these are different qualifications and different methods. Some assessors are qualified for both, in which case one visit can cover the building; otherwise the commercial and domestic assessments are arranged separately. Either way, the certificates themselves are always distinct.

We are only letting the shop, not the flats above — do we still need the flats assessed? Not for that letting. You need a valid non-domestic EPC for the commercial floor you are letting; the flats need their own domestic EPCs only when they are sold, let or constructed. If the flats sit empty or are owner-occupied and not being transacted, they do not need a certificate for your shop letting — but the moment a flat is let, it needs its own domestic EPC. Assessing the parts you are actually transacting is the rule.

Our commercial floor is rated F — does that affect the flats above? Legally, no — the flats are certificated and regulated separately, so an F on the commercial floor does not make the flats non-compliant. But an F commercial floor cannot lawfully be let or continue to be let without a registered exemption, so the shop itself is stranded until improved. Where one owner controls the freehold, the sensible move is to read the commercial recommendation report and clear the E line with the usual quick wins, while treating each flat’s compliance on its own footing.

How do we get the split right without ending up with the wrong certificates? Establish, before anything is lodged, which parts of the building are commercial and which are residential, and therefore how many non-domestic and domestic EPCs the building actually needs. That is exactly what a survey settles, and it is the step that prevents the classic mixed-use error — a single certificate, or the wrong type on the wrong part — that leaves an owner with an invalid or missing EPC when a sale or letting depends on it. Getting the split confirmed first is cheaper than unwinding it later.

Is there any funding for the improvements a mixed-use EPC recommends? There is no grant for the certificate itself — a commercial or domestic EPC is a professional service you pay for. Funding, where it exists, is for the improvements the report recommends, and mixed-use is one of the few cases where the 0% VAT relief on qualifying energy-saving materials is genuinely relevant, because that relief is targeted at residential accommodation. It applies to qualifying measures on the flats — the residential element — rather than blanket-covering the commercial floor. The Boiler Upgrade Scheme can also help fund a heat pump where a report recommends low-carbon heating. Both are downstream of the certificate, and the exact scope should be confirmed on the gov.uk notices; our grants and funding routes page sets out what applies and what does not.

Get a commercial EPC for your mixed-use building

Tell us the basics — the commercial floor area and type, how many flats sit above, and which parts you are selling or letting — and an accredited NDEA (Elmhurst, Stroma-NAPIT, Quidos or ECMK) will confirm the split, the assessment level for the commercial floor, and a fixed price. To get an accurate, no-obligation figure that covers the certificates your building actually needs, request a free commercial EPC quote and we will price it on the building in front of us, not a menu.