Verification under the UK Net Zero Carbon Buildings Standard is now open. Bureau Veritas, the scheme’s Verification Administrator, is accepting submissions, and the first buildings will start appearing on the public register as they’re confirmed Net Zero Carbon Aligned.
For anyone working on UK projects with net zero ambitions, this is worth understanding properly now, not once a verifier is already asking questions. Here’s what actually changed, how the process works, what evidence you need, and where the format requirements catch people out.
What actually opened
UK NZCBS Version 1 was published in March 2026, setting out the requirements a building has to meet to be called Net Zero Carbon Aligned. What launched more recently is the verification scheme itself, the independent, third-party process that checks whether a building’s evidence actually stacks up against those requirements.
Before this, teams could self-assess against the Standard, but there was no formal, accredited way to have that assessment independently checked and certified. Now there is. It’s still a voluntary standard, but it’s the first time the industry has had one agreed, verifiable definition of “net zero” for buildings, rather than everyone working to a slightly different version of the term.
Is it an application?
Not in the sense of applying once and waiting to hear back. It’s closer to a structured, staged process with your own evidence base at the centre of it. There are six steps:
1. Register. You register the building with UK NZCBS directly through their website, confirming your intent to verify and providing basic details about the building and claimant. Registration costs £500 per building (ex. VAT), with discounts available for Pilot participants and Pathfinder sponsors.
2. Collate. You build your evidence base. This is the bulk of the real work, and it’s where most of the detail in this article matters.
3. Submit. You appoint an accredited verifier (currently Bureau Veritas, with more verifiers expected to be trained and accredited over time) and submit your evidence to them, along with the completed submission proforma and an evidence tracker.
4. Outcome. The verifier reviews your evidence, raises queries, and works through them with you before reaching a final opinion.
5. Communicate. If successful, the building is added to the public UK NZCBS register.
6. Re-verify. Verification isn’t a one-off. Buildings need to be re-verified annually for at least the first two years, and then on a reduced cadence after that, provided nothing material has changed.
Verification administration fees are separate from registration and scale with building size, from roughly £1,190 for a small building’s re-verification up to £6,580 for the largest buildings’ first verification. Verifier fees are paid separately, direct to whichever verifier you appoint.
What evidence is actually needed
The core embodied carbon evidence requirement is a RICS Whole Life Carbon Assessment report, covering the full life cycle from product stage through to end of life. This has to follow the RICS Professional Statement 2nd edition, include both decarbonised and non-decarbonised scenarios, and be accompanied by a written methodology statement covering data sources, assumptions, emission factors, and functional unit.
Beyond the report itself, you’ll also need:
- Operational energy evidence, covering all fuel types used, evidenced through metering data, billing records, or automatic meter reads, for a full 12-month reporting period.
- Primary evidence behind the calculations, not just the summarised outputs. This includes things like material quantity data, Environmental Product Declarations, and building plans.
- Written justifications for any exclusions, assumptions, or estimates used anywhere in the assessment.
- Access to the actual calculation spreadsheet or tool, not just the report it produced. Where full access genuinely isn’t possible, the verifier can accept screenshots or a virtual walkthrough instead.
For embodied carbon specifically, the evidence has to cover concrete, steel, and enough of the remaining top-ten materials by carbon impact to reach 30% of the total. It’s a precise sampling requirement, not a general “provide your data” ask.
Formats that will catch people out
A few details in the guidance are easy to miss until a verifier flags them:
Raw data, not summaries. The verifier wants primary evidence “as close to the original source as reasonably possible.” Consolidated spreadsheets or internal summaries aren’t accepted as primary evidence, even if they’re accurate. The same goes for documents: originals traceable to the time of sourcing, not emails or interview notes describing them.
Meter photos have specific requirements. A photo of a meter reading needs to be clear, timestamped, show both the reading and the meter number, and show the wall area around the meter, including the connection. A cropped photo of just the display isn’t enough.
The 5% materiality threshold is stricter than it sounds. Errors are assessed per limit or target, not summed across the whole submission. A 4% error in one area and a separate 4% error in another area don’t add up to 8%, they’re each assessed on their own. But two errors within the same calculation area that total above 5% will push the claim into “material misstatement” territory, and the claim can’t pass until it’s corrected.
Estimation is allowed in only a few, tightly defined situations. Outside a small number of prescribed cases (like transport-to-site assumptions or refrigerant installation dates), estimation is only permitted where a meter has genuinely failed, and even then it’s capped at 18 days per meter per year, using a specific interpolation method between real data either side of the gap. Filling a gap with a benchmark, industry average, or modelled figure isn’t accepted under any circumstances.
Data sampling applies automatically to embodied carbon. Every embodied carbon verification uses data sampling, so it’s worth knowing in advance which materials are likely to be sampled (concrete, steel, and your top carbon-impact materials beyond that) rather than being asked for them mid-process.
What happens if you’re using eTool
If your Whole Life Carbon Assessments are already being produced through eTool, the core evidence requirement is largely already in the format the verifier expects. eTool’s reports conform to RICS WLCA methodology, so there’s no new report format or rebuild required to meet the primary evidence requirement for embodied carbon.
Two things are still worth checking on a project-by-project basis: confirming what can be offered for the calculation tool/spreadsheet access requirement (screenshots or a walkthrough are accepted where full access isn’t practical), and making sure the top-ten-materials sampling data is readily exportable in the format a verifier will want to see it.
What happens if you’re not
None of this evidence has to come from any particular platform, and manual or spreadsheet-based assessments can absolutely be verified, provided the methodology, sampling, and format requirements above are met. The practical difference is where the effort sits. Teams working from scratch need to build a RICS PS 2nd edition-conformant assessment, structure both decarbonised and non-decarbonised scenarios, and be ready to produce raw primary evidence (not summarised outputs) for whichever materials get sampled, all in the specific formats the verifier requires.
That’s a reasonable lift for a first submission, and a meaningfully bigger one if it needs to be repeated for annual re-verification. Getting the evidence base structured correctly from the outset, rather than reconstructing it retrospectively when a verifier asks, is the difference between a smooth first pass and a slow back-and-forth through query cycles.
The bottom line
Verification is still early days and the market is small, but the requirements are precise, not vague. Teams that understand the evidence format now, before they’re mid-submission, will move through the process faster than teams finding out the requirements as they go.
