A DIY business energy audit takes one to three days and can identify 10 to 20 per cent savings before any capital expenditure. The process covers metering, HVAC, lighting, standby loads, and envelope losses. ESOS and SECR are compliance audits, not the same as an operational cost-reduction audit.
Last reviewed: 12 May 2026
Why Businesses Skip the Audit and Pay for It Later
Most UK businesses that overpay on energy bills do so not because their contracts are bad but because they have no baseline. Without knowing which processes consume what share of energy, efficiency measures are guesswork. An audit creates the baseline.
A formal energy audit from an accredited assessor costs between £500 and £5,000 depending on site complexity. A DIY operational audit costs nothing beyond internal time, typically one to three days across a small or medium site, and can identify the majority of obvious waste before any spend is justified.
This guide covers how to run that internal audit, what to look for in 30 days, and how it differs from the compliance-driven ESOS and SECR processes that larger organisations are legally required to follow.
What a Business Energy Audit Actually Covers
An energy audit is a systematic review of how energy enters and leaves a building or process. It identifies where consumption is higher than it should be, why that is, and what the options are to reduce it. At the operational level, a business energy audit covers four main areas:
Metering and billing accuracy: Confirming that the consumption on your bill matches what your meters actually record, that your Meter Point Reference Number (MPRN) for gas or MPAN for electricity is correct, and that your Annual Quantity estimate used for billing reflects actual usage.
HVAC systems: Heating, ventilation, and air conditioning typically account for 40 to 60 per cent of energy use in commercial buildings according to DESNZ. An audit checks thermostat setpoints, scheduling, zone controls, and whether heating and cooling systems run simultaneously (a common source of waste in office buildings with mixed exposures).
Lighting: The audit records what lighting type is installed (LED, fluorescent, halogen), whether occupancy sensors or daylight-linked controls are present, and whether lighting runs during unoccupied periods. Lighting is usually the fastest-payback category.
Standby and baseload loads: These are the processes consuming electricity when the building is nominally unoccupied. Identifying overnight baseload via half-hourly meter data reveals equipment that was left on, systems that do not switch off, and server or refrigeration loads that may be larger than necessary.
The 30-Day DIY Audit Checklist
The following checklist is structured for a small to medium business with a single site. Work through each section in order. Document findings in a simple spreadsheet with columns for item, current state, recommended action, estimated saving, and cost to implement.
Week 1: Data gathering
- Obtain 12 months of gas and electricity bills or download half-hourly interval data from your supplier or data collector
- Calculate consumption by month and identify seasonal peaks
- Check whether your billed Annual Quantity (AQ) for gas or estimated annual consumption (EAC) for electricity matches your actual usage
- Walk the site outside of core hours and record which lights, screens, machinery, and HVAC are operating
Week 2: HVAC review
- Check boiler and HVAC service records: units not serviced in the last 12 months are likely running below rated efficiency
- Record heating setpoints and compare against CIBSE Guide A benchmarks (19 to 21 degrees Celsius for most office and retail applications)
- Identify whether heating and cooling zones overlap and whether any zones are heating unoccupied areas
- Check time-clock settings on boilers and AHUs: a common fault is pre-heat running from 5am for a building that opens at 8am
Week 3: Lighting and controls
- Photograph every lighting circuit and record type (LED, T8 fluorescent, T5, halogen, metal halide)
- Check whether external lighting, car parks, and stairwells are on timers or photocells
- Identify areas with daylight access that lack dimming controls
- Check whether PIR occupancy sensors are fitted in toilets, store rooms, and meeting rooms
Week 4: Standby and process loads
- Record meter readings at midnight and 6am on two consecutive weekdays to estimate overnight baseload
- Identify high-draw equipment: catering equipment, server rooms, compressors, printing equipment
- Check whether equipment has power management settings that are enabled
- Document any electric resistance heating (panel heaters, fan heaters) used as supplementary heat
ESOS and SECR: What They Are and Why They Are Not Enough
Two mandatory compliance frameworks cover large UK organisations: the Energy Savings Opportunity Scheme (ESOS) and Streamlined Energy and Carbon Reporting (SECR). Both require organisations to assess energy use, but neither is designed as an operational cost-reduction tool.
ESOS applies to large undertakings in the UK: organisations with 250 or more employees, or turnover above £44 million and balance sheet above £38 million. Under ESOS, qualifying organisations must carry out an energy audit every four years through a lead assessor registered with the Environment Agency. Phase 3 compliance deadline was January 2024. ESOS identifies significant energy consumption and recommends cost-effective improvements, but the scheme does not require implementation. Many organisations complete the compliance exercise without acting on the findings.
SECR applies to quoted companies and large unquoted companies. It requires disclosure of energy consumption and carbon emissions within the annual report but does not mandate a site-level audit or specific efficiency actions.
Neither framework covers micro or small businesses. For the majority of businesses reading this guide, ESOS and SECR are irrelevant to the immediate task of reducing operating costs. What matters is the operational audit described above, which focuses on actions that can be taken in 30 days at zero or low cost.
Benchmarking Your Consumption
Once you have 12 months of actual data, you can benchmark it against published norms. DESNZ publishes non-domestic energy consumption averages by sector in its Energy Consumption in the UK report. For offices, the CIBSE Building Energy Benchmark gives typical and best-practice consumption intensities in kWh per square metre per year.
Typical benchmarks for UK offices: - Typical: 160 to 240 kWh/m2/year (electricity and gas combined) - Good practice: 100 to 150 kWh/m2/year - Best practice: below 100 kWh/m2/year
If your site is consuming above the typical range, the audit process should reveal why. Common causes include poor controls, ageing HVAC plant, high process loads from catering or server equipment, or a building fabric with high heat loss that forces the heating system to run harder and longer.
When to Commission a Formal Audit
A DIY audit is sufficient for most small and medium businesses to identify and act on the quick wins. A formal audit from an accredited energy assessor becomes worthwhile when:
- Consumption exceeds 500,000 kWh per year across gas and electricity combined
- The business is considering capital investment in HVAC replacement, solar, or heat pumps and needs modelled payback projections
- A landlord or tenant dispute requires an independent assessment of a building's energy performance
- ESOS compliance requires a lead assessor sign-off
Formal auditors should be registered with one of the accreditation bodies recognised by the Environment Agency for ESOS purposes: CIBSE, EI, or IEMA.
Frequently asked questions
Editorial disclaimer: This information is provided for general guidance only and does not constitute professional energy consultancy advice. For complex sites or capital investment decisions, engage an accredited energy assessor.
What is the difference between an energy audit and an EPC?
An Energy Performance Certificate assesses the theoretical energy efficiency of a building's fabric and fixed services. An energy audit assesses actual operational consumption and identifies specific actions to reduce it. EPCs are required for commercial property lettings; energy audits are voluntary unless ESOS applies.
Does an energy audit qualify for any government support?
The UK Shared Prosperity Fund and certain Growth Hubs have offered subsidised energy audits for SMEs in some regions. Check with your local Growth Hub for current availability. The Energy Technology List also supports capital investment following an audit.
How long does a DIY audit take?
For a single-site business under 1,000 square metres, the data-gathering and walkthrough stages can be completed in one to two days. Documenting findings and prioritising actions typically takes a further half day.
What should I do if my billed consumption does not match my meter?
Contact your supplier and request a meter read reconciliation. If the discrepancy is material, ask for a meter accuracy test. Under Ofgem's licence conditions, suppliers are required to investigate billing disputes within a defined timeframe.
Is an ESOS audit the same as an energy efficiency audit?
No. ESOS is a compliance exercise that identifies significant energy consumers and recommends improvements. It does not require businesses to implement changes. An operational energy audit focuses on actionable steps to reduce costs within a specific timeframe.
How we verified this
This article draws on published guidance from Ofgem, the Department for Energy Security and Net Zero, and the primary legislation and regulatory sources listed in the Sources section. No aggregator or supplier-produced content was used as a primary source.
