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Last updated October 2026.
Two schemes, two purposes
ESOS is an energy efficiency scheme: every four years, large organisations must audit their energy use and identify savings. SECR, Streamlined Energy and Carbon Reporting, is a disclosure scheme: every year, large companies and LLPs must report their energy use, greenhouse gas emissions, an intensity ratio and the efficiency measures they have taken, in the directors’ report (or, for LLPs, a separate energy and carbon report) that goes to Companies House.
One looks for opportunities; the other publishes outcomes. An organisation in both, which is most large companies, finds that the measurement work for one is most of the measurement work for the other.
Side by side
| ESOS | SECR | |
|---|---|---|
| Who | Large undertakings: 250+ employees, or turnover above £44m and balance sheet above £38m; groups containing one | Quoted companies, plus large unquoted companies and LLPs meeting two of: 250+ employees, turnover above £36m, balance sheet above £18m |
| How often | Every four years | Every financial year |
| What | Energy audit of at least 95% of consumption, savings identified, lead assessor sign-off, action plan and annual progress updates | Energy use in kWh, Scope 1 and 2 emissions in tCO2e, at least one intensity ratio, methodology, and a narrative of efficiency action taken |
| Where | Notified to the Environment Agency; action plan published | Directors’ report filed at Companies House |
| Regulator | Environment Agency and devolved equivalents | Companies House and the Financial Reporting Council via company law |
| Penalty | Civil penalties up to £50,000 plus daily amounts | Company law consequences for a defective directors’ report |
Talk it through with us
Send us a recent bill or a quick description of your sites and we will tell you plainly what applies to you and what it would involve. No obligation.
Running both off one dataset
The consumption data for SECR is the consumption data for ESOS: electricity, gas, other fuels and transport, by site, for a twelve-month period. An organisation that builds a clean annual dataset for SECR has done the measurement stage of ESOS every year, and its ESOS reference period can simply be one of those years. The ESOS action plan, in turn, is a ready-made narrative of efficiency measures for the SECR report, and the progress updates give SECR something real to say each year.
The practical implication is to treat the two as one energy data process with two outputs rather than two compliance projects. The SECR glossary entry covers the reporting mechanics; the ESOS pillar covers the assessment.
Frequently asked questions
Do I have to do both ESOS and SECR?
If you meet both sets of thresholds, yes. Most large UK companies do. The thresholds are similar but not identical, so check each separately.
Can SECR data be used for ESOS?
Yes. The annual consumption dataset built for SECR is the measurement stage of ESOS, and one of those years can be the ESOS reference period.
Is SECR annual or four-yearly?
Annual, as part of the directors’ report for each financial year. ESOS is four-yearly.
Does SECR require an energy audit?
No. SECR requires disclosure of energy, emissions and efficiency action; it does not require an audit. ESOS requires the audit.
Which is the regulator for SECR?
SECR is a company-law disclosure filed at Companies House, with the Financial Reporting Council overseeing reporting quality. ESOS is administered by the Environment Agency.
Can Clearsight Energy help with SECR and ESOS data?
We help organisations consolidate billing and consumption data across sites and fuels, which is the foundation of both, and link it to procurement and invoice review so the work pays for itself.
Your questions on this, answered in order
The questions businesses actually ask about this topic, in the order they tend to ask them. Each answer leads to the next; where we can help, there is a link.
Does my business have to report its gas use and carbon emissions?
Quoted companies, and large unquoted companies meeting two of 250 employees, £36 million turnover or an £18 million balance sheet, must report energy and carbon under SECR. Those thresholds didn’t change with the April 2025 company size updates. Smaller firms aren’t required to report, but customers and tenders increasingly ask suppliers for carbon data anyway.
How do I calculate carbon emissions from my business gas use?
Multiply your gas consumption in kWh by the government’s greenhouse gas conversion factor for natural gas, published each year by DESNZ. The current figure is roughly 0.18 kg CO2e per kWh on a gross calorific value basis. Gas burned on site counts as Scope 1 emissions. Use actual readings rather than estimates for the reporting period.
Where do I get accurate gas data for carbon reporting?
Start with bills based on actual readings, then fill gaps with supplier portal data or AMR readings where you have them. For multiple sites, pull every MPRN into one list so nothing is missed. Estimated bills and periods straddling a supplier switch are where reporting data usually goes wrong, so check those first.
Does a green gas tariff reduce my reported emissions?
It depends on the reporting method. Under standard location-based reporting, gas burned on site still uses the national conversion factor. Some frameworks allow biomethane certificates to support a lower market-based figure, but the rules are still developing and auditors vary in what they accept. Check with whoever signs off your report before relying on it.
Should we be doing ESOS as well as SECR?
They’re separate. ESOS applies to large undertakings with 250 or more employees, or turnover above £44 million and a balance sheet above £38 million. For Phase 4 the qualification date is 31 December 2026 and the compliance deadline is 5 December 2027. A business can fall into one scheme, both or neither, so check each set of thresholds.
Can you help with ESOS and pull together my gas data?
Yes. Clearsight Energy can help you check whether ESOS applies, gather your gas and electricity data across sites and support you through the Phase 4 process. Send a list of your sites and recent bills to start, and we’ll explain what the scheme asks of you in plain terms. Get in touch →
A customer wants our carbon footprint, where do we start?
Start with the energy you buy and burn. Gas and any fuel used in vehicles are Scope 1, and purchased electricity is Scope 2. Gather twelve months of bills, convert the kWh using the government’s conversion factors, and state the period and method you used. That covers what most customers ask for from smaller suppliers.
Can you pull together a year of gas and electricity data for my carbon report?
Yes. Clearsight Energy can help gather a year of consumption data from your gas and electricity accounts, flag gaps or estimated periods and present it in a form you can use for carbon reporting. Share your MPRNs, MPANs or recent bills to get started. Get in touch →
Need help? Get in touch
Call us on 020 8036 5715, or email us, and we will take it from there.