Methodology

How Térrea calculates your footprint.

Written for the person who has to stand behind the numbers: the finance director signing an SECR statement, the bid team publishing a Carbon Reduction Plan, the auditor or customer asking how a figure was reached. It describes the platform as it runs now, and it starts with what you can inspect.

What you can inspect

Each line of the footprint keeps the activity data it came from, the factor applied and its year, the calculation, the result, and the rule that put it in its scope and category, with the version of the rules at the time. Here is one line for the example organisation used across this site, with the 2025 UK Government factors the platform holds.

The same record exists for every line, whether it came from a meter, a mileage claim, a travel file, a spend export or a direct entry, and it is what the review each cycle works from.

Standards and factors

Footprints follow the GHG Protocol Corporate Standard, its Scope 2 Guidance and the Corporate Value Chain (Scope 3) Standard. SECR figures follow the UK Environmental Reporting Guidelines. The Carbon Reduction Plan follows the PPN 006 template.

Emission factors are the UK Government GHG Conversion Factors for Company Reporting, published each year by DESNZ. Térrea extracts them from the official annual files, holds the 2022 to 2026 sets, and applies the set for the year of the activity. Where the set for an activity year is not yet published, the most recent set is used and the report lists the years it used. Hotel nights use the Greenview Hotel Footprinting factors, which are per room night and per country, where a country factor exists; otherwise the UK Government hotel factor applies. Spend-based figures use the UK Government input-output factors for the spend category.

Boundary

Your organisation is set up as one or more entities with their locations, and emissions are calculated per entity and consolidated for the reporting period. For each location, and for each meter where that matters, the platform records who controls the source and the status of the evidence behind that: confirmed, assumed, under review or missing. A leased office you control is your Scope 1 and 2. A serviced office where the landlord runs the plant moves to Scope 3 category 8, upstream leased assets, once the evidence is confirmed. Until then the energy stays in your Scope 1 and 2 and the record shows the evidence status, so a reviewer can see what is settled and what is still assumed.

What is calculated, and how

Scope 2 on both bases

Location-based Scope 2 is calculated for every supply from the UK grid average. For the market-based figure, you upload the renewable electricity certificate, power purchase agreement or supplier tariff confirmation, and record the instrument type, the meters it covers and the months it is valid for, on an annual matching basis. The person uploading attests to it. The platform reads the document and checks it against those entries, sets the market-based figure to zero for the covered meter-months, and leaves months outside the certificate at the grid figure. What the platform does not do is verify retirement with the issuing registry; that remains between you and your supplier, and the review each cycle asks for it where the amount is material.

The GHG report shows Scope 2 on both bases and leads with market-based, as does the Carbon Reduction Plan. SECR reports the location-based figure, which the UK guidelines recommend as the primary basis.

Data quality

Every line carries one of four classes, and the reports roll them up: activity-based for measured consumption; estimated for figures calculated or interpolated from what you have, including refrigerants from floor area and any gap filled between two bills; spend-based for figures derived from money spent; manual for a tonnage entered directly. Spend-based figures are screening estimates. Where a spend category is material, the review asks for the underlying quantities and the line is replaced, and its class changes with it.

The reports

The GHG report gives Scope 1, Scope 2 on both bases and Scope 3 by category for the period, with the factor years and data quality classes it used, and downloads as Excel. The SECR report gives energy in kWh, with vehicle distance converted using the SECR kWh factors, Scope 1 and 2 emissions on the location basis, transport emissions where you choose to include them, the intensity ratio you select, a comparison with the previous year once one exists, your energy efficiency actions and a note where the low-energy exemption applies. The Carbon Reduction Plan gives the baseline and current footprints for Scope 1, Scope 2 and the Scope 3 categories the PPN 006 template requires, the targets, completed and planned initiatives, and the declaration. Both documents download as Word files for your own branding and sign-off. A signed-off Carbon Reduction Plan returns to draft if a target or initiative behind it changes, so the published plan and the record cannot drift apart unnoticed.

Targets and net zero

Reduction planning follows the criteria of the SBTi Corporate Net-Zero Standard, version 1.3.1. You set a near-term target five to ten years out and a long-term net zero target no later than 2050, each against a baseline year no earlier than 2015. As you do, the platform checks the structure against the standard's criteria: Scope 1 and 2 targets aligned to 1.5°C, at least 4.2 percent a year; a Scope 3 target when Scope 3 is 40 percent or more of the baseline, covering at least two thirds of it near term and 90 percent long term; renewable electricity as an accepted route for Scope 2, with the 80 percent and 100 percent milestones. This is an advisory check to get the target right before you submit; validation is done by SBTi, not by Térrea. Each reduction measure is logged with its status, its estimated impact and, once delivered, its measured impact, and progress is shown against the target trajectory year by year. Carbon credits are recorded but not counted toward the target, as the standard requires. The Carbon Reduction Plan reads its baseline, targets and initiatives from this same record.

The review, and what it is not

With Professional, each reporting cycle includes a review with a carbon-accounting specialist before the reports are used. It covers completeness (which sources, locations and months are missing or filled by estimate), the boundary and evidence status of each location, the calculation method for anything unusual (a shared meter, an office move, a supplier's own figures), and the data quality mix behind the headline. It is our review of your record; it is not independent assurance, which an accredited third party provides against the same record and which we scope separately when you need it.

Coverage

The platform calculates Scope 1, Scope 2 and Scope 3 categories 1 to 8. Downstream categories 9 to 15 are not calculated. Whether any of them is material for your organisation is a question the review asks at setup and each cycle, and the answer is recorded with the report's assumptions.

Changes to this page

September 2026

Page first published. Describes routing rules version 2026-06-09.

June 2026

Boundary evidence per location and meter, with category 8 routing once evidence is confirmed. Renewable electricity certificates held in the platform with meter and month coverage. Business-travel well-to-tank moved from category 3 to category 6.

Questions about the method go to contact@terrea.earth. This page is revised whenever the routing rules or factor sets change.