Commercial energy assessors: what businesses need to know
Commercial property runs on a separate assessment system from housing — different qualifications, different software, different price structure. If you own, let or occupy non-domestic premises, this page covers the essentials before you book.
When a commercial assessment is required
A non-domestic EPC is legally required when a commercial building is constructed, sold or let, and the certificate must be available to prospective parties from the point of marketing. Under MEES, let commercial property must also rate at least E — a continuing obligation, not just a transaction-day one, with penalties scaled to rateable value reaching £150,000 per property for sustained breaches. The proposed moves to C by 2027 and B by 2030 remain consultation proposals in 2026, but they are already shaping lender and tenant behaviour.
Mixed-use property splits along the use boundary: the flat above the shop gets a domestic EPC from a DEA, the shop gets a non-domestic certificate. Booking both together is normal and usually cheaper.
The level system, briefly
Non-domestic assessors qualify at Level 3 (simple buildings — natural ventilation, basic heating), Level 4 (air conditioning and complex services — most modern offices) or Level 5 (buildings needing full dynamic simulation). The required level is set by the building, and an under-levelled certificate is invalid. The rough practical test: any air conditioning beyond a server-room split usually means Level 4 minimum; atria and automated facades mean Level 5.
Modelling differs too. Levels 3 and 4 use SBEM, the government's standard calculation; Level 5 uses dynamic simulation software that models the building hour by hour. Both produce the familiar A+ to G certificate plus a recommendation report ranking improvements by payback.
What commercial assessments cost
| Building | Typical fee |
|---|---|
| Small shop / office unit (Level 3) | £250–£400 |
| Industrial unit / warehouse (Level 3) | £280–£450 |
| Air-conditioned office or retail (Level 4) | £450–£900 |
| Complex building requiring DSM (Level 5) | £1,200+ |
The pricing drivers mirror the domestic market scaled up: floor area, zoning complexity, documentation quality and travel. Buildings with good drawings and plant documentation consistently quote lower and rate better, because SBEM punishes missing evidence with conservative defaults.
Booking through us vs going specialist
For straightforward Level 3 work — the shop, the unit, the small office — our standard matching service handles it: accredited non-domestic assessor, verified level, fixed price, one working day. For larger instructions, portfolios, or anything with air conditioning and a deadline attached, we route enquiries to commercial EPC assessment specialists whose entire workload is Level 4 and 5 buildings — better turnaround on complex stock than generalists can offer.
Either route, the same verification rules apply as for domestic work: check the assessor's accreditation and level on the official register before the survey. The find-an-assessor guide shows how, and the general assessment walkthrough covers what survey day involves — commercial surveys differ mainly in scale and the depth of plant inspection.
One adjacent duty worth checking
If your building has more than 12 kW of air conditioning in total — counted across all units — you also need a TM44 inspection every five years, by yet another accreditation. It is the most commonly missed commercial energy duty in the UK and surfaces at the worst time: mid-transaction. While arranging an EPC, totalling the cooling nameplates takes a minute and can save a £300 penalty plus a due-diligence scramble.