Methodology
How we calculate your carbon footprint
A report is only useful if people trust it. This page explains exactly how your figures are worked out, what is included, and what is not.
The standard we follow
Greenhouse gas emissions are calculated in line with the GHG Protocol Corporate Accounting and Reporting Standard, the framework used by most companies worldwide. We use the operational control approach, which means your report covers the premises, vehicles and activities your business controls.
Results are expressed in tonnes of carbon dioxide equivalent (tCO₂e), which rolls all the main greenhouse gases into a single comparable number.
Where the emission factors come from
Every calculation uses theUK Government GHG Conversion Factors for Company Reporting, published each year by the Department for Energy Security and Net Zero. Many people still call them theDEFRA factors.
The factor year is chosen from the midpoint of your reporting period. If factors for that year have not been published yet, the nearest available set is used. Air travel factors include radiative forcing, which accounts for the extra warming effect of emissions released at altitude.
How each figure is calculated
The basic sum is always the same:
Activity (for example kWh, litres, miles or passenger kilometres) multiplied by the emission factor equals emissions in kg CO₂e.
Your report's appendix lists every line of that working, along with the factor used, so an investor, auditor or buyer can follow it from start to finish.
Electricity: location-based and market-based
Scope 2 electricity is reported two ways. The location-based figure applies the UK grid average to all the electricity you use. The market-based figure reflects your tariff: electricity on a renewable tariff backed by REGOs counts as zero, and the remainder uses the grid average. Headline totals use the location-based figure. You can read more in ourlocation-based vs market-based explainer.
When you do not have the exact numbers
Most small businesses do not have every bill to hand, and that is fine. Where measured data is not available, the questionnaire estimates emissions from information you can give us, combined with published UK benchmarks:
- Office electricity and gas from your floor area, using CIBSE TM46 office energy benchmarks
- A co-working share from the number of desks and the days a week you use them
- Waste from your bin sizes and collection frequency
- Water from your headcount, using a CIRIA typical office benchmark
- Flights from the number of trips in each distance band
- Employee commuting from days in the workplace, how many staff travel by car, bus or rail, and a typical distance
- Homeworking from full-time equivalent staff and the days they work from home
- Purchased goods and services, if you choose to include them, from your annual spend
Benchmark estimates are pro-rated to the length of your reporting period. If there is not enough information to make a fair estimate, the source is shown as a data gap rather than guessed.
Data quality ratings
Every source in your report carries one of four labels:
- Measured: from bills, meter readings, fuel receipts, contractor weights or booking records.
- Estimate from activity data: your own records combined with standard averages, such as recorded flights with average route distances.
- Estimate from benchmark: published benchmarks applied to your business, such as floor area or headcount.
- Data gap: information needed for a calculation was not available, so the source is excluded from totals.
A source takes the rating of its lowest-quality part. Your overview shows the percentage of your footprint that is measured.
What the footprint covers
The footprint covers the sources a small business controls directly, plus theScope 3 categories it can realistically estimate: purchased goods and services, well-to-tank and transmission losses, courier deliveries you pay for, waste, water, business travel, commuting and homeworking. Commuting, homeworking and spend-based figures are rough estimates and are labelled as such. Inbound freight paid for by your suppliers and the downstream categories (8 to 15) are not assessed yet. If a buyer or tender asks for them, you can add them separately.
| Scope | Category | Included | Basis |
|---|---|---|---|
| Scope 1 | Heating: mains gas, heating oil and LPG | Yes | From bills or deliveries, or estimated from floor area |
| Scope 1 | Fuel used in plant, machinery and generators | Yes | From fuel purchased |
| Scope 1 | Company cars, vans and HGVs | Yes | From fuel purchased or mileage by vehicle type |
| Scope 1 | Refrigerant (F-gas) leakage | Yes | From refrigerant added during servicing |
| Scope 2 | Purchased electricity | Yes | Location-based and market-based |
| Scope 2 | Electric vehicle charging | Yes | UK electricity for EVs factors |
| Scope 3 | Purchased goods, services and equipment (optional) | Yes | Spend-based estimate |
| Scope 3 | Water supply and treatment | Yes | From bills, or estimated from headcount |
| Scope 3 | Fuel and energy related (well-to-tank, transmission losses) | Yes | Calculated from your energy and fuel data |
| Scope 3 | Courier deliveries paid for by the business | Yes | Parcels, weight and distance |
| Scope 3 | Waste generated in operations | Yes | From contractor data, or estimated from bins |
| Scope 3 | Business travel by air and rail | Yes | Flights by distance band and class, rail journeys |
| Scope 3 | Business travel in private cars, taxis and hotels | Yes | Mileage claims, taxi miles and hotel nights |
| Scope 3 | Employee commuting | Yes | Estimated from days in, travel modes and distance |
| Scope 3 | Homeworking | Yes | Estimated from full-time equivalents and homeworking days |
| Scope 3 | Inbound freight from suppliers | Not yet | Not assessed |
| Scope 3 | Downstream and investment categories (Cat 8 to 15) | Not yet | Not assessed |
Social and governance
The social and governance sections record your practices rather than calculate them. Each one is marked as established, developing, not in place, not applicable or unknown, based on your answers. Nothing is scored against other businesses, so the report describes where you are without judging you.
Limitations and assurance
Your report is based on the information you provide and is not independently verified or assured. That is normal and expected for a small business. Estimates carry more uncertainty than measured figures, and the report says clearly which is which, so you can replace estimates with real data in future years.
Questions about our approach? Email us at [email protected].
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