Guide
Commercial energy audit: what's included and 2026 costs
Updated
A commercial audit is priced by the walking: floor area, plant rooms, meters and systems. Here is what a proper one includes, what it costs in 2026, and how to make sure the report earns its fee.
What a proper audit includes
- Site walkthrough: plant rooms, distribution, lighting, controls, building fabric, and how the building is actually used against how it was designed to be used.
- Metering and data review: half-hourly electricity data, gas consumption, sub-meters where they exist; the out-of-hours baseload is usually where the first finding lives.
- Systems assessment: HVAC plant and setpoints, lighting types and controls, hot water, compressed air or process loads where relevant.
- A costed report: measures ranked with estimated cost, saving and payback, not a list of platitudes. If the sample report has no numbers, keep shopping.
What it costs
| Premises | Typical cost |
|---|---|
| Small unit, under 500 m2 | £500–£1,000 |
| Medium premises, 500–2,000 m2 | £1,000–£2,500 |
| Large or multi-site estates | £2,500+, priced per portfolio |
Floor area is the headline driver, but system count matters as much: a simple warehouse audits faster than a smaller building with full HVAC, BMS and process plant. Multi-site work is usually quoted per portfolio with a day rate underneath. These are typical 2026 quote ranges, not fixed prices, get quotes for your actual site.
Walkthrough or detailed?
Most firms offer two depths: a walkthrough audit (one visit, data review, top measures) at the bottom of the range, and a detailed or investment-grade audit (sub-metering, longer monitoring, verified savings cases suitable for board or lender sign-off) at the top and beyond. Buy the depth your decision needs: a lighting refit needs a walkthrough; a £200k plant replacement justifies investment-grade.
Display Energy Certificates
Public buildings over 250 m2 that are occupied by a public authority and frequently visited by the public also need a Display Energy Certificate showing actual energy use, larger buildings renew the certificate annually with a periodic advisory report (gov.uk DEC guidance). DECs are a compliance document; the audit is what finds the savings the DEC exposes.
Getting a useful audit
- Gather 12 months of bills and any half-hourly data first. An assessor quoting blind quotes high; good data cuts the survey time you pay for.
- Ask for a sample report and check the measures carry costs and paybacks, not just recommendations.
- Get more than one quote, day rates for the same survey genuinely differ. Our form gets local assessors quoting your actual building, free.