How we work

Our methodology.

The standards we work to, where the numbers in a report actually come from, and the review step every deliverable goes through before it reaches you. Common to Carbon Reduction Plans, embodied carbon assessments and UK CBAM supplier verification.

Last updated: 24 September 2026
This page describes how work is carried out across all three services. It sits alongside, not instead of, the specific standards and disclosures set out in the engagement letter for a given piece of work.

Standards we work to

Every deliverable is built against a named standard, not a proprietary format invented for the occasion. Which ones apply depends on the service:

PPN 06/21The mandated format and content for a Carbon Reduction Plan submitted against a UK public sector contract requiring one.
PAS 2080Carbon management in buildings and infrastructure, the reference framework for how embodied carbon is scoped and reported.
RICS Whole Life Carbon AssessmentThe RICS professional statement's methodology for whole life carbon in the built environment, including life cycle stage boundaries (A1-A5, B, C, D).
GHG Protocol Corporate StandardScope 1, 2 and 3 classification and boundary-setting for organisational carbon footprints.
UK Government GHG Conversion FactorsThe published annual conversion factors used to turn activity data (fuel, electricity, mileage) into emissions where a more specific factor isn't available.
UK CBAM frameworkThe registration threshold, embedded emissions methodology and default value structure set out for UK CBAM ahead of 1 January 2027.

The data hierarchy

Not every number in a report carries the same weight, and we say so rather than presenting all of them with equal confidence. In order of preference:

Verified primary dataSite-specific figures, a supplier's own measured embedded emissions, actual metered energy use, a real bill of quantities. Used wherever it's available and checked for plausibility.
Supplier or sector-specific dataFigures specific to a supplier's process or product line where full verification isn't available, but the source is named and traceable.
National or sector default valuesPublished conversion factors or CBAM default values, used as a conservative fallback when nothing more specific exists, always labelled as a default in the report, never presented as measured.

The default value explainer goes into why that labelling matters specifically for CBAM, where a default value can cut either way against a supplier's actual position.

Tools we use

One Click LCAEmbodied carbon modelling for whole life carbon and PAS 2080 assessments
UK Government GHG Conversion FactorsActivity-based emissions calculation where primary data isn't available
Companies House public dataConfirming registered company details and sector on CBAM enquiries, an administrative check, not part of an emissions calculation
UK Trade Tariff (HMRC)Cross-checking a commodity code against CBAM's in-scope headings on the exposure calculator

None of these tools replace judgement, they narrow down the manual work of checking a figure against its source, which is where most of the time on an engagement actually goes.

Review before delivery

Every report goes through the same check before it's sent: the calculated figures are read back against the source documents, drawings, a bill of quantities, an energy bill, a supplier declaration, rather than taken as correct because a model produced them. Material take-offs are sense-checked the way a structural review would, not accepted at face value from a spreadsheet. Where an assumption had to be made because the data wasn't available, it's stated in the report as an assumption, not folded into the total silently.

What we won't do

We won't present a default or estimated figure with the same confidence as a verified one. We won't quote a UK CBAM cost or rate ahead of the real figures being published, anything shown before then is explicitly illustrative. We won't extend a report's stated purpose to cover a use it wasn't scoped for without confirming that the scope still fits.

Keeping this current

PPN 06/21, RICS guidance and UK CBAM are all still being actively developed or phased in. This page is reviewed whenever a standard we work to changes materially, and the date at the top reflects the last review, not just the last time the page was edited.

Questions about how a specific figure in a report was arrived at are always welcome, email hello@driftwatch.co.uk.

See it applied to your own numbers.

The free calculator and the UK CBAM exposure check both use the same standards described above.

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