Software · the measurement layer, cited
Carbon accounting software: what the number underneath has to survive
Carbon accounting software builds the emissions inventory that every SECR statement, UK SRS disclosure and CDP response is drawn from.
This page sets out what that inventory has to withstand — a new factor year, a changed Scope 3 method, a restated base year, an assurance practitioner’s questions — with each test cited to the provision that creates it.
This site has tested no products, ranks none and recommends none; the vendor register lists seventeen in their own published terms.
Two layers, two questions
Carbon accounting builds the number; carbon reporting formats it
The words are used interchangeably, and most products sell both layers, so the distinction is about which question you are asking.
Carbon accounting software answers “is this figure right, and can we show how we got it?”; carbon reporting software answers “is this output in the shape the regulation requires?”.
The accounting layer captures activity data, applies the government’s conversion factors or others, and assembles an inventory to the GHG Protocol Corporate Standard.
It hands the reporting layer a figure and the working behind it.
A failure in the reporting layer shows at once: a missing line, a wrong format.
A failure in the accounting layer can sit unnoticed for a year, because a wrong figure in the right format looks finished until somebody asks how it was made.
The discipline itself — scopes, boundaries and the UK anchors — is set out in carbon accounting, and what the law obliges a company to publish in carbon reporting.
| Layer | Its job | Governed by |
|---|---|---|
| Measurement (accounting) | Activity data × emission factors, organised by scope and category, with the working kept | GHG Protocol Corporate and Scope 3 Standards; DESNZ factors; UK SRS S2 ¶29(a)(ii) |
| Restatement | Base year, recalculation policy, comparatives | GHG Protocol 2019 Guidance; Sch 7 ¶18, ¶20H |
| Disclosure (reporting) | The SECR lines, the UK SRS metrics, the CDP response | SI 2008/410 Sch 7; UK SRS S2; FCA UKLR 6.6.6R |
| Assurance | Evidence a practitioner can sample | ISSA (UK) 5000 (voluntary); UKLR 6.6.6R(8)(d) statement |
Do you have to measure?
Which UK duties need an inventory, and what each takes from it
SECR, ESOS and UK SRS S2 draw on the same activity data, which is the strongest argument for measuring once and taking each disclosure as a view.
| Duty and status | Who | What it takes from the inventory |
|---|---|---|
| SECR · in force, SI 2008/410 Sch 7 | Quoted companies; large unquoted companies and LLPs exceeding two of £36m turnover, £18m balance sheet, 250 employees | kWh, emissions from gas, electricity and transport fuel, a ratio, the methodology, comparatives |
| UK SRS S2 (listed) · comply or explain from 1 Jan 2027, PS26/19 | Companies in UKLR 6, 14, 15, 16 and 22 | Gross Scope 1, 2 and 3; location-based Scope 2; Scope 3 categories included; changes in approach |
| UK SRS S2 (voluntary) · DBT, 25 Feb 2026 | Any UK entity | As above, by choice |
| energy savings opportunity scheme · in force, SI 2014/1643; Phase 4 notification by 5 Dec 2027 | Large undertakings and their groups | Total energy in kWh by purpose, and the evidence behind it |
| PPN 006 · procurement policy | Bidders for in-scope central government contracts | Scope 1 and 2, and five named Scope 3 categories |
| CDP · voluntary | Companies asked by customers or investors | A climate response from the same inventory |
The SECR size test is framed as “not more than” qualifying conditions on the exempt side, so an unquoted company is in when it exceeds at least two, judged over two consecutive years after the first.
The listing-rule duty is comply or explain across all of UK SRS under the FCA’s PS26/19, which replaced the CP26/5 proposal; nothing in UK SRS is fully mandatory, and a one-year Scope 3 relief applies.
ESOS adds its own tooling question, covered on ESOS software.
What each regime requires a platform to output, line by line, is on carbon reporting software; this page stays with the layer underneath.
The five principles
Relevance, completeness, consistency, transparency, accuracy
The GHG Protocol’s Corporate Standard opens with five principles that accounting and reporting “shall be based on”: relevance, completeness, consistency, transparency and accuracy.
They are written for companies, not tools, but a tool decides whether a company can meet two of them.
Consistency fails when a tool overwrites last year’s factors, because the figure already published can no longer be reproduced.
Transparency fails when a tool keeps the result but not the trail, because no one can say who changed a figure or why.
The Standard also warns against minimum-emissions thresholds, calling one “a predefined and accepted negative bias” that is not compatible with completeness — a useful line to hold against any tool that drops “immaterial” sources by default.
Chapter 3 requires a choice between the equity share and control approaches, and under control between financial and operational control.
How those choices play out across a group is covered in the GHG Protocol.
| Principle (GHG Protocol Ch 1) | What it asks of software |
|---|---|
| Relevance | A boundary that reflects the company’s real emissions, set by a stated consolidation approach |
| Completeness | Every source in the boundary accounted for; exclusions disclosed and justified |
| Consistency | Methods held steady over time, so last year can be reproduced and compared |
| Transparency | A clear audit trail behind each figure |
| Accuracy | Neither systematically over nor under, as far as can be judged |
The tests before you sign
Six groups of tests, each tied to its provision
The test list beside this changes with what your inventory has to feed; tick the regimes and commitments that apply.
Run every test on your own data, because a demonstration dataset is built to look finished and yours is not.
Factor versioning. DESNZ publishes a set each year, and the 2026 methodology paper says at ¶1.10 that a set is for activity data falling entirely or mostly within its year.
A tool that holds one library and refreshes it cannot reproduce last year; how the sets work is on GHG conversion factors.
Scope 2. UK SRS S2 requires location-based Scope 2 and treats market-based as optional, under ¶29(a)(v) and ¶B30 of the standard; the GHG Protocol’s own guidance asks for both where contractual instruments exist.
Scope 3 method. The Scope 3 Standard asks a company to account for all Scope 3 and justify exclusions, while UK SRS S2 asks it to consider all fifteen categories and disclose those included.
UK SRS S2 then asks for the extent of Scope 3 measured from activity-specific and from verified inputs, so the method has to be stored per category, not inferred from a total; the listed-company position is on UK SRS Scope 3 reporting.
Restatement. The base year and the recalculation policy, below.
Audit trail. A record of who entered and changed each figure, kept as the work happens.
Data model. Your real entities, joint ventures and year end, because UK SRS S1 ¶20 ties the sustainability report to the same reporting entity as the financial statements.
The exit. An export of inventory, factors by version and methodology notes in a form another tool could rebuild from.
Step 1 · what does your inventory have to feed?
Step 2 · 18 tests to run on your own data
Factor versioning
Scope 2
Scope 3 method
Restatement and the base year
Audit trail
Data model
The exit
Each test is our reading of the cited provision as something to see on screen; the provision is the authority.
Tick a test once the vendor has shown it on your data.
Nothing you tick is stored or sent.
Restatement and the base year
The capability hardest to add later
A base year is what makes a trend mean something, and it has to be recalculated when the company becomes a different thing.
The GHG Protocol’s 2019 Inventory Guidance lists the triggers: significant changes in structure, significant changes in calculation methodology, and significant errors, including small ones that are collectively significant.
It sets no figure for “significant”; the company sets and discloses its own threshold, and the guidance gives 2 percent only as an example.
A science-based target runs on a separate rule: GHG Protocol’s technical assistance notes that the SBTi requires a threshold of 5% or less for recalculating target emissions.
In software terms, the test is simple: restate the base year for an acquisition and see whether the original survives beside the restated version, or is overwritten.
SECR keeps last year beside this year in the directors’ report, under paragraphs 18 and 20H of Schedule 7, and UK SRS S2 asks at ¶29(a)(iii) for changes in measurement approach and the reasons.
The checker beside this works through a structural change against the 2019 Guidance.
Restatement checker · 2019 Guidance and Chapter 9
The standard is changing
GHG Protocol and ISO are consolidating — a method change on the way
On 29 July 2026 the GHG Protocol announced that it and ISO are aligning their standards development around a single, co-branded corporate standard.
The consolidation brings the GHG Protocol’s Scope 1, Scope 2, Scope 3 and Actions and Market Instruments work together with ISO 14064-1, following a partnership announced by ISO on 9 September 2025.
The Standard Development Plan estimates a consolidated draft for public consultation in Q2 2027 and a published revised standard in Q4 2028, and says the timeline is subject to change.
The title of the new standard is, in the plan’s words, still to be determined with ISO.
Nothing changes today: the existing standards stay in effect, and UK SRS S2 ¶29(a)(ii) still points at the 2004 Corporate Standard as amended.
KPMG’s commentary on the agreement discusses how standard-setters that reference the GHG Protocol might respond; that is commentary, and the dates above are the GHG Protocol’s own.
For a buyer the consequence is practical: a platform bought now will probably still be in place when the method moves, which makes restatement the capability to test hardest.
- 9 Sep 2025ISO and GHG Protocol partnership announced
To align their corporate carbon accounting standards.
- 29 Jul 2026Consolidation confirmed
GHG Protocol’s Scope 1, 2 and 3 and Actions and Market Instruments work, with ISO 14064-1, into one co-branded standard.
- Est. Q2 2027Consolidated draft for public consultation
Standard Development Plan v2.0, §9.
- Est. Q4 2028Revised standard published
Guidance documents to follow publication.
Assurance and the audit trail
Assurance is optional; the statement about it is not
No UK rule requires a company to have its sustainability figures assured.
Under the FCA’s final rules, a listed company that does obtain assurance says who provided it, which disclosures were assured and which assurance standards were used, under UKLR 6.6.6R(8)(d) as made by PS26/19.
The international standard for such engagements is the IAASB’s ISSA 5000; the FRC’s UK version, ISSA (UK) 5000, was issued on 12 November 2025 for voluntary use and is effective for periods beginning on or after 15 December 2026.
The government’s SECR guidance likewise records no statutory requirement to have SECR figures audited.
What assurance does require, whenever a company commissions it, is evidence a practitioner can sample: source documents linked to lines, and a history of changes.
A platform either keeps that lineage as the work happens or someone rebuilds it afterwards, and the second costs more.
The UK assurance position in full is on sustainability assurance.
The words buyers use
Tool, platform, system — and the categories next door
A carbon accounting tool usually means a calculator: activity in, CO2e out — enough for a first Scope 1 and 2 inventory, not for an assurance practitioner.
A carbon accounting platform implies the machinery around the calculation: data connections, a factor library with versions, an entity model, permissions and an audit trail.
A carbon accounting system is the same thing described by whoever has to integrate it, which is why the questions turn to the ERP and procurement data.
“GHG accounting software” uses the standard’s own term; a vendor fluent in it should answer questions about consolidation approaches and Scope 2 methods without reaching for a dashboard.
Emissions tracking software emphasises frequency — monthly rather than annual — which is useful, but a wrong number tracked more often is still wrong.
Carbon management software adds reduction planning and targets to accounting; the family’s sister guide to carbon management software covers that broader market.
Carbon footprint and carbon labelling software usually means a product footprint, which is governed by product standards rather than the corporate inventory: the picker beside this names the standard for what you need, and Sphera’s profile reads one product-level vendor’s offer.
Financed emissions are a separate purchase again: portfolio accounting under PCAF, whose Part A is now in its third edition, is a different problem from operational Scope 1 to 3.
For property portfolios, IBM’s Envizi buildings page describes a module for building-level energy and benchmark reporting, one example of the specialist modules some platforms sell.
What are you trying to produce?
Use: ISO 14067:2018; or PAS 2050:2011 from BSI; or the GHG Protocol Product Life Cycle Standard. Each covers one impact category, global warming.
Status: ISO 14067:2018 is current but at stage 90.92, “to be revised”, with ISO/WD 14067.2 at working-draft stage and no date. GHG Protocol and ISO formed a joint working group in February 2026 on a harmonised product standard.
What it does not do: ISO 14067 puts carbon offsetting and communication of the footprint outside its scope; PAS 2050 sets no disclosure requirements.
ISO record 71206 — Bible [417]; BSI Knowledge, PAS 2050:2011; GHG Protocol Product Standard page
From each standard’s public catalogue record; ISO clause text is paywalled and is not quoted.
Nothing is stored or sent.
The vendor register
Seventeen vendors, alphabetically, in their own published terms
Each row links this site’s profile of the vendor, written from the vendor’s own pages; none is a review, and the order is alphabetical, which ranks nothing.
| Vendor | Published price status | Ownership events, in the owners’ words |
|---|---|---|
| Climatise | Enterprise level · TBD | — |
| Cority | Enterprise level · TBD | Thoma Bravo majority investor (2019); acquired Greenstone (May 2023) |
| Emitwise | Not sold standalone since July 2025 | Software acquired by Green Project Technologies (July 2025) |
| Greenly | Enterprise level · TBD | Merger with Normative announced (September 2026) |
| IBM Envizi ESG Suite | Pricing model by account bundle; no figure on IBM’s page · TBD | — |
| Microsoft Sustainability Manager | US$4,000 or US$12,000 per tenant, per month | — |
| Normative | Enterprise level · TBD | Merger with Greenly announced (September 2026) |
| Persefoni | Pro plan free; some reports are add-ons | — |
| Plan A | Enterprise level · TBD | Acquisition by Diginex closed (14 January 2026) |
| Salesforce Net Zero Cloud | £168,000 per org per year (Growth) | — |
| Sami | Enterprise level · TBD | SGS majority stake (21 November 2025) |
| Seedling | Free Starter plan; others by quote | — |
| SINAI Technologies | Enterprise level · TBD | — |
| Sphera | Enterprise level · TBD | — |
| Sweep | Enterprise level · TBD | — |
| Watershed | Enterprise level · TBD | — |
| Workiva Carbon | Enterprise level · TBD | — |
Two vendors publish a full price: Microsoft for Sustainability Manager and Salesforce for Net Zero Cloud Growth.
Two publish free entry plans: Persefoni and Seedling.
IBM publishes a pricing model for Envizi, by bundles of accounts, without a figure; it also lists Envizi on AWS Marketplace.
Everything else is quoted on request, and assurance, where commissioned, is priced separately from any software.
Ownership has moved under several of these products in the past two years: Emitwise is no longer sold on its own, and Sami is now majority-owned by SGS, so check who you would be contracting with.
Every profile follows one method: the vendor’s own words, dated, set against the UK provisions they touch, with demo questions tied to those provisions.
The claims each vendor makes about SECR, UK SRS, ISSB, CSRD, ESOS and PPN 006 are tabulated side by side on carbon reporting software, and the GHG mechanics on GHG reporting software.
Software or a spreadsheet
When a spreadsheet stops being enough
A single-site company with no assurance practitioner and no Scope 3 duty can carry its first Scope 1 and 2 inventory in a spreadsheet.
The SECR disclosure itself — the lines a SECR reporting tool has to produce — is short, and the SECR reporting guide walks through it.
The spreadsheet stops coping when three things arrive together: a factor year that must not overwrite the last, a change history someone outside the team will read, and Scope 3 categories built on suppliers’ data.
CDP’s supply-chain programme, described in its Strengthening the chain work, is one route by which customers start asking suppliers for that data.
The 2026 review of SECR, informed by the independent evaluation of the regulations published on 29 January 2026, retained the regime; the inventory it needs is not going away.
Whichever you use, UK SRS S2 points the measurement at the GHG Protocol, under ¶29(a)(ii), and the standards themselves are on UK SRS S1 and S2; DBT published them on 25 February 2026.
Scope 3 as a subject in its own right is covered on Scope 3 emissions.
Nothing on this page is a rating, ranking or recommendation of any product.
If you want to talk through which tests matter for your own reporting, you can book a free 15-minute call.
Frequently asked
Carbon accounting software, answered
What is carbon accounting software?
Software that builds a greenhouse gas inventory: it takes activity data such as energy, fuel, travel and purchases, applies emission factors, and organises the result by Scope 1, Scope 2 and the fifteen Scope 3 categories under the GHG Protocol.
Its job is the figure and the working behind it; the reporting layer turns that figure into a SECR, UK SRS or CDP disclosure.
Which is the best carbon accounting software?
This site does not rank products and has tested none.
The useful question is which product passes the tests your reporting regimes impose — factor versioning, Scope 3 method by category, restatement, audit trail and a data model that holds your group — on your own data.
The test list on this page is built from those provisions.
What are the five principles of carbon accounting?
Chapter 1 of the GHG Protocol Corporate Standard sets five: relevance, completeness, consistency, transparency and accuracy.
Consistency and transparency are the two a software choice most affects, because they turn on whether past figures can be reproduced and whether each figure has a clear audit trail.
How much does carbon accounting software cost?
Most vendors in this site’s register do not publish a price.
Microsoft publishes Sustainability Manager at US$4,000 or US$12,000 per tenant, per month, and Salesforce publishes Net Zero Cloud Growth at £168,000 per org per year; Persefoni and Seedling offer free entry plans.
Assurance, where a company commissions it, is a separate cost.
Is there free carbon accounting software?
Two vendors in the register publish free plans: Persefoni’s Pro plan, with some reports sold as add-ons, and Seedling’s Starter plan.
A spreadsheet can also carry a first Scope 1 and 2 inventory; it stops coping when you need a version history, an audit trail and Scope 3 across suppliers at once.
What is the difference between carbon accounting software and carbon reporting software?
Accounting is the measurement layer — activity data, factors, Scope 3 methods, the base year.
Reporting is the disclosure layer — the SECR lines, the UK SRS metrics, the CDP response.
Most products sell both; a weakness in the accounting layer gives the right format around the wrong number.
Does carbon accounting software have to use the UK government conversion factors?
UK SRS S2 prescribes no factors (¶B29) but asks an entity to prioritise factors that relate to the jurisdiction where the activity happened (¶B51); for UK activity those are the DESNZ conversion factors, which DESNZ describes as relevant to SECR reporting.
Each year’s set is for activity data falling within that year, so a tool must keep every year’s set, not overwrite it.
Is the GHG Protocol changing, and does it affect which software to buy?
Yes.
On 29 July 2026 the GHG Protocol confirmed it is consolidating its corporate standards with ISO 14064-1, with a draft for consultation estimated for Q2 2027 and publication estimated for Q4 2028.
Existing standards stay in effect meanwhile; a platform bought now is likely to face that method change, so its ability to restate a prior year while keeping the original matters.
Do I need carbon accounting software, or will a spreadsheet do?
A spreadsheet can carry a first single-site Scope 1 and 2 inventory.
It stops being adequate when an assurance practitioner asks who changed a figure and why, when a new factor set must not overwrite last year, or when Scope 3 depends on supplier data you do not control.
Has this site tested any carbon accounting software?
No. This site has tested no products.
The page is built from the requirements of the GHG Protocol, UK SRS, SECR and the FCA’s rules, each cited to its provision, and the vendor register quotes only what each vendor publishes about itself.
Sources
Primary sources
Every test on this page traces to the provision listed here.
Vendor prices and ownership events are cited on each vendor’s profile to the vendor’s own page.
- GHG Protocol (WRI, WBCSD)A Corporate Accounting and Reporting Standard — Chapters 1, 3 and 9
The five principles, the consolidation approaches, the required minimum of Scope 1 and 2.
- GHG ProtocolCorporate Value Chain (Scope 3) Standard, §6.2 and Table 5.4
All Scope 3 accounted for, exclusions disclosed and justified; the fifteen categories.
- GHG ProtocolScope 1 & 2 GHG Inventory Guidance (2019)
Base-year recalculation and the company’s own significance threshold.
- GHG ProtocolGHG Protocol announces key standard development updates (29 July 2026)
The consolidation with ISO 14064-1.
- GHG ProtocolConsolidated Corporate Standard — Standard Development Plan v2.0 (29 July 2026), §9
Consultation estimated Q2 2027; publication estimated Q4 2028.
- ISOISO and GHG Protocol announce strategic partnership (9 September 2025)
The partnership behind the consolidation.
- Department for Energy Security and Net ZeroGovernment conversion factors for company reporting
The UK factor sets, one per activity year.
- Department for Energy Security and Net Zero2026 GHG conversion factors methodology paper, ¶1.10
Factors are for activity data falling entirely or mostly within the year.
- Department for Business and TradeUK Sustainability Reporting Standards S1 and S2
Published 25 February 2026 for voluntary use.
- Department for Business and TradeUK SRS S2 Climate-related Disclosures (PDF), ¶29(a), ¶B29, ¶¶B30–B57
What the measurement layer must produce for a UK SRS report.
- Financial Conduct AuthorityPS26/19 — final rules on UK SRS reporting by listed companies
Comply or explain for periods from 1 January 2027; the assurance statement.
- Financial Conduct AuthorityCP26/5 — the consultation
The proposal the final rules changed.
- legislation.gov.ukSI 2008/410, Schedule 7 Parts 7 and 7A
The SECR lines: kWh, emissions, ratio, methodology, comparatives.
- GOV.UK (DESNZ, Defra)Environmental Reporting Guidelines, including SECR requirements
The government SECR guidance, including that there is no statutory requirement to audit SECR figures.
- Department for Energy Security and Net ZeroStreamlined Energy and Carbon Reporting regulations: evaluation (29 January 2026)
The evaluation behind the 2026 review of SECR.
- IAASBISSA 5000, General Requirements for Sustainability Assurance Engagements
The international assurance standard; the FRC’s UK version is for voluntary use.
- CDPStrengthening the chain
CDP’s supply-chain programme, through which customers request suppliers’ data.
- PCAFThe Global GHG Accounting and Reporting Standard for the Financial Industry
Part A Financed Emissions, third edition (December 2025).