ESOS · UK SRS S2 · Integration
ESOS and UK SRS: what your energy audit can do for a climate disclosure
ESOS and UK SRS answer different questions: ESOS is a four-yearly UK energy audit duty under the ESOS Regulations 2014, and UK SRS S2 is a climate disclosure standard that listed companies now report against on a comply-or-explain basis under the FCA’s PS26/19.
The energy data ESOS gathers is useful to an S2 disclosure, but it arrives in kWh, for the UK, over a reference period of its own.
This page maps each ESOS output to the S2 paragraph it can inform, and states the gap each time.
Who is in which
Two regimes, two different tests for who is in
ESOS asks whether a UK undertaking is large on its qualification date, under Schedule 1 to the ESOS Regulations, and pulls its whole UK group in with it.
The FCA’s final rules ask a different question: whether a company’s securities sit in one of five listing categories.
Those are UKLR 6 commercial companies, UKLR 14 secondary listings, UKLR 15 depositary receipts, UKLR 16 non-equity and non-voting shares, and UKLR 22 transition companies.
Closed-ended funds, open-ended investment companies, shell companies and debt and miscellaneous securities are outside them.
No size threshold applies to UK SRS, and no UK entity outside those listing categories is required to use it; the UK SRS scope page goes through the categories.
Many listed groups will clear the ESOS test, but a small listed company can be in UK SRS and outside ESOS, and a large private group in ESOS and outside UK SRS.
Whether ESOS applies is worked through on the ESOS Phase 4 compliance guide.
| ESOS | UK SRS (FCA rules) | |
|---|---|---|
| Who | UK large undertakings and their groups | Listed companies in UKLR 6, 14, 15, 16 and 22 |
| Test | At least 250 staff, or turnover over £44m and balance sheet over £38m | The listing category, with no size test |
| Basis | Statutory duty, with civil penalties | Comply or explain |
| Output | Energy assessment, notification, action plan | Disclosures in the annual financial report |
| Cycle | Four-yearly, plus annual updates | Every annual report |
| Regulator | Environment Agency and the other UK regulators | Financial Conduct Authority |
Output by output
What each ESOS output gives S2, and where it stops
Filter by the four S2 pillars.
Each row names the ESOS provision, the S2 paragraph it can inform, what transfers and what does not.
ESOS output → UK SRS S2
Total energy consumption, in kWh reg 22; Sch 3 Table G
→ Absolute gross Scope 1 and Scope 2 emissions, in tonnes of CO2 equivalent UK SRS S2 ¶29(a)(i)–(ii)
Gives: Activity data for fuels and purchased electricity, already gathered and reviewed.
Gap: Energy is not emissions: each fuel needs an emission factor, and ESOS counts UK energy only, over a reference period that need not match the financial year.
Consumption by organisational purpose reg 25B; Sch 3 Table G
→ Where in the business model risks and opportunities are concentrated UK SRS S2 ¶13(b)
Gives: A split of energy across transport, industrial processes, buildings and other uses.
Gap: A purpose split is not a split by facility, geography or asset type; S2 leaves the cut to the entity.
Energy intensity ratios reg 25C
→ Industry-based metrics, and metrics used to set and monitor targets UK SRS S2 ¶¶32, 37
Gives: A ratio per purpose on a denominator the participant chose.
Gap: S2 does not name these ratios; whether one is a useful metric is the entity’s judgement.
Transport energy, scoped by who is supplied with the fuel EA Phase 4 guidance §4.3.4
→ Scope 1 and Scope 3 boundaries under the GHG Protocol UK SRS S2 ¶29(a)(ii)
Gives: Fuel data for company cars, fleet vehicles and personal or hire cars on business use.
Gap: Flights and rail the company does not operate are outside ESOS but may be Scope 3 business travel.
Audit savings opportunities, with estimated annual kWh and £ reductions reg 27(1)(d)
→ How the entity is responding to climate-related risks and opportunities UK SRS S2 ¶14(a)
Gives: A costed list of efficiency measures with paybacks.
Gap: Efficiency is one transition lever; S2 also asks about business model, value chain and resilience.
The ESOS action plan: measures, dates and kWh savings to 2031 reg 34A(3)
→ Any climate-related transition plan, and how targets will be achieved UK SRS S2 ¶14(a)(iv)–(v)
Gives: Dated, quantified measures a plan can cite.
Gap: An action plan is not a transition plan; it may even state that no measure is proposed.
Progress updates and savings achieved regs 34B, 27D
→ Progress of plans disclosed in earlier periods UK SRS S2 ¶14(c)
Gives: Annual, signed-off evidence of what was implemented and the kWh it saved.
Gap: ESOS updates run on December windows, not the financial year.
Savings achieved against the plan reg 27D; reg 27E
→ Performance against each climate-related target UK SRS S2 ¶35
Gives: kWh achieved per measure, and the measures dropped with reasons.
Gap: ESOS sets no target, so there is nothing in ESOS to measure performance against.
Responsible officer confirmation of the assessment, plan and updates regs 31, 34A(8), 34B(7)
→ The body or individual overseeing climate-related risks and opportunities, and how they are informed UK SRS S2 ¶6
Gives: A named director who has seen and considered the audit and the plan.
Gap: One sign-off every few years is not a description of oversight, skills, frequency or remuneration links.
Lead assessor review reg 21(2)
→ Whether third-party assurance was obtained, and over what UKLR 6.6.6R(8)(d)
Gives: An independent check that the assessment meets the ESOS Regulations.
Gap: It is a review against the ESOS Regulations, not assurance over the S2 disclosures.
No equivalent —
→ Processes to identify, assess, prioritise and monitor climate-related risks UK SRS S2 ¶25
Gives: Nothing directly.
Gap: ESOS is an audit of energy use; it has no risk-management limb.
SI 2014/1643 as amended; Environment Agency Phase 4 guidance; UK SRS S2 (DBT, February 2026); FCA PS26/19 Appendix 1.
The mapping is this site’s reading of where the texts meet, not a statement by either regulator.
The strongest link is in metrics: ESOS measures energy carefully, and energy is the activity data behind most Scope 1 and Scope 2 emissions.
The weakest is risk management, where ESOS has nothing to offer, because it is an audit of energy use rather than of risk.
Strategy sits between: an action plan is evidence of intent with dates and numbers, but it is narrower than anything S2 asks about a transition.
From kWh to tonnes
Energy is not emissions: the conversion S2 needs
ESOS reports total energy consumption in kWh, or in pounds of energy spend; the Environment Agency’s guidance says plainly that CO2 is not an energy unit.
UK SRS S2 paragraph 29(a) asks for absolute gross Scope 1, Scope 2 and Scope 3 emissions in tonnes of CO2 equivalent, measured under the GHG Protocol Corporate Standard of 2004.
Getting from one to the other means applying an emission factor to each fuel and to electricity.
For UK activity the usual source is the DESNZ greenhouse gas conversion factors, and the factor year should match the year of the activity data, not the year of publication or filing; the GHG conversion factors page sets out the sets.
S2 requires Scope 2 on a location-based approach, with information about contractual instruments only where it helps a reader; market-based figures are permitted, not required, as the Scope 2 emissions page explains.
ESOS electricity in kWh, multiplied by a location-based grid factor for the matching year, is therefore a sound starting point for the UK part of Scope 2.
ESOS fuel data does the same for stationary and mobile combustion in Scope 1, with one boundary caution covered below.
Scope 3 is where ESOS helps least: the scheme measures the participant’s own consumption, not its value chain, and the FCA’s rules give a one-year Scope 3 relief during which a company states only that it is using it.
Boundary, period, scope
Three mismatches to reconcile before reuse
The boundary differs first.
ESOS counts all energy consumed in the UK by the participant, including assets an overseas group member holds here, and nothing consumed abroad.
A UK SRS disclosure is for the same reporting entity as the related financial statements, under UK SRS S1 paragraph 20, which for most listed groups includes overseas operations.
The period differs second.
Regulation 22(5) sets the ESOS reference period as 12 consecutive months beginning no more than 12 months before the qualification date and ending on or before the compliance date.
UK SRS S1 paragraph 64 requires sustainability disclosures to cover the same period as the financial statements and to be reported at the same time.
The third difference is transport, which ESOS scopes by whether the organisation is supplied with the fuel for business use; flights and rail the company does not operate are outside ESOS but may be Scope 3 business travel.
| ESOS | UK SRS S2 | |
|---|---|---|
| Boundary | The participant’s UK energy, whoever in the group holds the asset | The same reporting entity as the financial statements (S1 ¶20) |
| Period | A 12-month reference period ending by the compliance date | The same period as the financial statements (S1 ¶64) |
| Transport | Fuel the organisation is supplied with for business use | GHG Protocol scopes: owned or controlled sources in Scope 1, others in Scope 3 |
| Unit | kWh or £ spend | Tonnes of CO2 equivalent |
| Frequency | Once per four-year phase, then annual updates | Every annual report |
Choosing the window
One choice that lines the two up, for a calendar year end
The reference period is a choice, and it can be made with the annual report in mind.
For Phase 4 the earliest permitted start is 31 December 2025 and the latest permitted end is 5 December 2027.
A company with a 31 December year end can therefore use calendar 2026 as its ESOS reference period, which is also its financial year 2026, on our reading of regulation 22(5).
Its first year under the FCA’s rules is 2027, for which UK SRS S2 needs no comparative figures in the first period; the 2026 data is the natural base for the comparatives that follow.
A company with another year end cannot align the windows exactly, but it can choose the ESOS period that overlaps most with a financial year it will report.
The audit’s own data window is a separate test, starting no earlier than 6 December 2022 and no more than 24 months before the audit; the panel tests both on your dates.
Two twelve-month windows · Phase 4
1 · Reference period for total energy consumption (reg 22(5))
- Regulation 22(5)(a): begins no more than 12 months before the qualification date (on or after 31 December 2025).
- Regulation 22(5)(b): ends 31 March 2027, on or before the compliance date, 5 December 2027.
- Environment Agency guidance §4.4 (not the regulation): the period should include 31 December 2026; this one does.
A valid Phase 4 reference period.
2 · Data behind an energy audit (GOV.UK step 5; EA guidance §8.3)
- Begins on or after 6 December 2022.
- Begins within 24 months of the audit start (no earlier than 1 March 2025).
- Ends 31 December 2026, on or before 5 December 2027.
- The audit starts inside the compliance period.
Usable for a Phase 4 audit, provided it was not relied on for an audit in Phase 3.
Rules from SI 2014/1643 reg 22(5), the Environment Agency’s guidance §4.4 on including the qualification date, the GOV.UK ESOS page (rewritten 2 September 2026) and the Environment Agency’s Phase 4 guidance §8.3.
Twelve consecutive months are read as ending the day before the anniversary of the first day.
Plans
An action plan is not a transition plan
An ESOS action plan, under regulation 34A(3), lists each energy efficiency measure the participant proposes, whether an audit recommended it, the date it will go in, and the expected savings in kWh, or states that no measure is proposed.
The Phase 4 plan is due by 5 December 2028 and covers 6 December 2027 to 5 December 2031, and the Environment Agency publishes it.
UK SRS S2 paragraph 14(a)(iv) asks about any climate-related transition plan the entity has, including the key assumptions and dependencies behind it.
The FCA’s rule is narrower still: a listed company in UKLR 6, 16 or 22 states whether it has published a climate-related transition plan and where, or why it has not, under UKLR 6.6.6R(8)(e) and its equivalents.
Nothing in either regime requires a company to have a transition plan.
The ESOS plan’s dated measures and the three progress updates against it are useful evidence inside a transition plan, and for the S2 paragraph 14(c) disclosure on progress of plans disclosed before.
The UK SRS transition plans page sets out what S2 and the FCA ask for; ESOS data cannot carry that on its own.
Comply or explain
Where ESOS evidence sits in a comply-or-explain statement
Under UKLR 6.6.6R(7A), a listed company either makes S2 disclosures or states which S2 requirements it has not met, why, and the steps it is taking or plans to take.
A company with ESOS data for its UK operations has activity data for UK Scope 1 and 2 in hand, and an explanation that omits those figures has less to point to.
The same company may lack equivalent data for overseas operations, and that difference is the kind of thing an explanation describes.
How the FCA’s rules work in full, including the reliefs and the draft technical note, is on the UK SRS and the FCA page, and the S2 requirements paragraph by paragraph are on the UK SRS S1 and S2 page.
UK SRS S1 and S2 were published by the Department for Business and Trade on 25 February 2026 as voluntary standards.
The FCA’s final rules require listed companies in scope to report against them, or explain, for periods from 1 January 2027.
Nothing in UK SRS is fully mandatory.
Sign-off and assurance
A director’s confirmation, and what it is not
ESOS puts a named responsible officer on record confirming the assessment, the action plan and each update, having seen and considered them.
UK SRS S2 paragraph 6 asks how the board or another body oversees climate-related risks and opportunities, how often it is informed and how it takes them into account.
A responsible officer’s ESOS sign-off is a small piece of evidence for that description, not a substitute for it.
The lead assessor’s review checks the assessment against the ESOS Regulations; it is not third-party assurance over sustainability disclosures.
The FCA’s rules ask a company to say whether it obtained such assurance and, if so, from whom, over which disclosures and to which standards; assurance itself is not required.
Both calendars
ESOS and UK SRS dates, on one line
- 30 Sep 2026FCA PS26/19 published
Comply or explain across UK SRS for periods from 1 January 2027.
- 5 Dec 2026ESOS Phase 3 second progress update
- 31 Dec 2026ESOS Phase 4 qualification date
- 1 Jan 2027FCA rules apply to accounting periods beginning on or after this date
- 5 Dec 2027ESOS Phase 4 notification of compliance
- 2028First annual reports under the FCA’s UK SRS rules
For calendar-year companies, the year 2027.
- 5 Dec 2028ESOS Phase 4 action plan
Then progress updates by 5 December 2029, 2030 and 2031.
Every ESOS date is set out with its rule on the ESOS reporting page and the UK SRS dates on the UK SRS compliance page.
The regime in between
SECR, the annual energy disclosure
Between ESOS and UK SRS sits SECR, the annual energy and carbon disclosure in the reports of companies that meet its own size test.
It is a different regime with a different test from ESOS, and SI 2026/701 did not align the two.
The same UK energy data serves ESOS every four years and SECR every year, which is set out on the ESOS vs SECR page.
For a listed company, the FCA’s ¶1.10 says the new rules replace the existing TCFD-aligned disclosures, so the climate section of the annual report is where UK SRS, SECR and the ESOS evidence meet.
The ESOS guidance documents and which one governs each step are on the ESOS compliance guidance page, and the scheme as a whole on the Energy Savings Opportunity Scheme page.
The underlying ESOS instruments are SI 2023/1182 and SI 2026/701, with the regulator’s reading in the Phase 4 guidance and on the GOV.UK ESOS page; the standards themselves are on the UK SRS publication page, and the FCA’s rule text is in PS26/19 Appendix 1.
Check yourself
Six statements about ESOS and UK SRS
Each answer names the provision it rests on.
The statements cover the points most often blurred when the two regimes are discussed together: units, status, plans, Scope 2, boundary and the transition plan statement.
For a question about your own organisation, you can book a free 15-minute call.
True or false?
01ESOS consumption can be reported in tonnes of CO2.
02Under PS26/19, UK SRS S2 is mandatory and S1 is comply or explain.
03An ESOS action plan may say that no measure is proposed.
04UK SRS S2 requires Scope 2 on a location-based approach.
05ESOS energy data covers the whole global group.
06A listed company must say whether it has published a climate transition plan.
6 statements.
Pick an answer to see the provision behind it.
Answers rest on the provisions named beside each one.
Nothing you pick is saved.
Frequently asked
ESOS and UK SRS, answered
Does ESOS data count towards UK SRS reporting?
It can inform it.
UK SRS S2 asks for Scope 1, 2 and 3 greenhouse gas emissions in tonnes of CO2 equivalent, measured under the GHG Protocol Corporate Standard, for the same entity and period as the financial statements.
ESOS records energy in kWh for the UK participant over a 12-month reference period.
ESOS consumption data is useful activity data for Scope 1 and 2, but it has to be converted, and its boundary and period checked against the financial statements.
Which companies are in both ESOS and UK SRS?
The tests are different.
ESOS applies to UK large undertakings — at least 250 employees, or turnover in excess of £44 million and a balance sheet total in excess of £38 million — and their groups.
The FCA’s final rules (PS26/19) apply UK SRS on a comply-or-explain basis to listed companies in UKLR 6, 14, 15, 16 and 22.
Many listed companies will also be in ESOS, but neither test implies the other.
Is UK SRS S2 mandatory for listed companies?
No. Under the FCA’s final rules in PS26/19, published on 30 September 2026, listed companies in scope report against UK SRS S1 and S2 on a comply-or-explain basis for accounting periods beginning on or after 1 January 2027, with first reports in 2028.
A company that does not make an S2 disclosure, or makes it only in part, must summarise what is missing, why, and the steps it is taking.
Can an ESOS action plan be a UK SRS transition plan?
No. An ESOS action plan is a list of energy efficiency measures, dates and kWh savings for the next four years, or a statement that none is proposed.
UK SRS S2 asks about any climate-related transition plan the entity has, including its assumptions and dependencies.
The ESOS plan’s measures can be cited inside a transition plan, but it is not one.
The FCA’s rules require a statement of whether a transition plan has been published, and where, not that one exists.
Is an ESOS lead assessor review a form of assurance?
Not of UK SRS disclosures.
The lead assessor reviews whether the ESOS assessment meets the ESOS Regulations.
The FCA’s rules ask listed companies to state whether they obtained third-party assurance over their sustainability disclosures and, if so, from whom, over what and to which standards; assurance itself is not required.
Can ESOS energy data be used for Scope 2?
Yes, as activity data.
UK SRS S2 requires Scope 2 on a location-based approach, with information about contractual instruments where it helps users understand the figure.
ESOS electricity consumption in kWh multiplied by a location-based grid factor for the matching year gives a location-based figure, for the UK part of the entity only.
Why might ESOS figures not match the annual report?
Because the reference period need not be the financial year, ESOS counts only energy consumed in the UK, and the ESOS participant is the UK group, while UK SRS disclosures must cover the same reporting entity and period as the financial statements.
Transport is also scoped differently: ESOS includes it where the organisation is supplied with the fuel.
Do ESOS and UK SRS share a deadline?
No. The ESOS Phase 4 notification is due by 5 December 2027.
UK SRS disclosures under the FCA’s rules are made in the annual report for accounting periods beginning on or after 1 January 2027, so a calendar-year company first reports in 2028 for the year 2027.
Sources
Primary sources
Every figure, date and status on this page traces to the instrument’s owner.
Secondary commentary is never the source for a number.
- legislation.gov.ukThe Energy Savings Opportunity Scheme Regulations 2014 (SI 2014/1643)
The ESOS duties whose outputs this page maps.
- legislation.gov.ukSI 2014/1643, Schedule 1 — the large undertaking test
Who ESOS catches: a size test, not a listing test.
- legislation.gov.ukSI 2014/1643, regulation 22 — total energy consumption and the reference period
The 12-month window ESOS energy data covers.
- legislation.gov.ukSI 2014/1643, Part 6A — action plans and progress updates
The plan and updates set against S2’s transition plan and progress paragraphs.
- legislation.gov.ukThe Energy Savings Opportunity Scheme (Amendment) Regulations 2023 (SI 2023/1182)
Introduced action plans, intensity ratios and the ESOS report.
- legislation.gov.ukThe Energy Savings Opportunity Scheme (Amendment) Regulations 2026 (SI 2026/701)
kWh throughout, savings achieved per measure, and the third progress update.
- Environment AgencyHow to comply with the Energy Savings Opportunity Scheme (ESOS) phase 4
Total energy consumption in kWh or £, UK energy only, and the transport scope test.
- GOV.UK (Environment Agency)Energy savings opportunity scheme (ESOS): find out if you qualify and how to comply
Phase 4 dates and the voluntary net zero assessment that MESOS cannot receive.
- Department for Business and TradeUK Sustainability Reporting Standards: UK SRS S1 and UK SRS S2
Where the standards were published on 25 February 2026.
- Department for Business and TradeUK SRS S2 Climate-related Disclosures
Governance ¶6, strategy ¶¶13–14, risk management ¶25, metrics ¶29, targets ¶¶33–37.
- Department for Business and TradeUK SRS S1 General Requirements
Same reporting entity (¶20) and same period as the financial statements (¶64).
- Financial Conduct AuthorityPS26/19: Aligning listed issuers’ sustainability disclosures with international standards
The final rules: comply or explain across UK SRS, for periods from 1 January 2027.
- Financial Conduct AuthorityPS26/19, Appendix 1 — UKLR 6.6.6R(7A) and (8)
The S2 explain limb, the assurance statement and the transition plan statement.
- GHG ProtocolA Corporate Accounting and Reporting Standard (Revised Edition, 2004)
The method UK SRS S2 ¶29(a)(ii) requires for Scope 1, 2 and 3.
- Department for Energy Security and Net ZeroGreenhouse gas reporting: conversion factors 2026
Turning ESOS kWh into tonnes of CO2 equivalent, year matched to the data.