Activity data
A physical measure of something your business did, such as kWh of electricity, litres of diesel, miles driven or tonnes of waste. Multiplied by an emission factor, it gives emissions. Read our footprint calculation guide.
Additionality
Whether a carbon project would have happened without the money from selling credits. A credit from a project that would have gone ahead anyway represents no extra climate benefit. Read our carbon offsetting guide.
Allocation
Dividing your total emissions between customers or products, usually by share of revenue or a physical measure such as units or weight, so a customer can include its share in its Scope 3. Read our guide to customer data requests.
Assurance (verification)
An independent check of a greenhouse gas report. Optional for SECR and PPN 006. Usually carried out against ISO 14064-3 or ISAE 3410.
Base year recalculation
Restating your baseline when the business changes shape, for example through an acquisition, or when you find a significant error, so comparisons stay like for like. The SBTi uses a 5% significance threshold.
Baseline year
The year your emissions are measured against. A Carbon Reduction Plan reports it alongside your latest year, so reductions can be seen.
Biogenic emissions
CO2 released by burning biomass or biofuels. The UK government factors report it separately as 'outside of scopes', because the carbon was absorbed as the plants grew. Methane and nitrous oxide from burning them are still counted.
Carbon budget
Under the Climate Change Act 2008, a legally binding cap on total UK greenhouse gas emissions over a five-year period, set at least 12 years ahead on the advice of the Climate Change Committee.
Carbon credit
A tradeable certificate representing one tonne of CO2e reduced, avoided or removed by a project, issued under a standard and recorded on a registry. When retired against your own emissions it is called an offset. Read our carbon offsetting guide.
Carbon neutral
A claim that emissions have been balanced, usually with carbon credits. The international standard is now ISO 14068:2026. The CMA expects any claim that relies on offsetting to say so. Read our carbon offsetting guide.
Carbon offset
A carbon credit used to compensate for your own emissions. Offsets don't reduce your reported footprint under the GHG Protocol, SECR or PPN 006. Read our carbon offsetting guide.
Carbon Reduction Plan (CRP)
A public document reporting your Scope 1, 2 and selected Scope 3 emissions and committing to net zero. Required for major UK government and NHS contracts. Read our Carbon Reduction Plan guide.
Carbon removal
Taking CO2 out of the atmosphere and storing it, in forests, soils, rock or underground. Net zero standards accept only removals to balance residual emissions. Read our carbon offsetting guide.
CBAM (carbon border adjustment mechanism)
A charge on imports of carbon-intensive goods, so they face a carbon price like domestic production. The EU's CBAM entered its definitive phase in 2026. The UK CBAM starts on 1 January 2027 for aluminium, cement, fertiliser, hydrogen, and iron and steel, for importers bringing in £50,000 or more of those goods in 12 months.
CDP
A not-for-profit that runs a global environmental disclosure system. Many large companies ask their suppliers to respond through CDP's supply chain programme. Read our guide to customer data requests.
Climate Change Act 2008
The UK law that sets the national target of net zero greenhouse gas emissions by 2050 (amended from an 80% cut in 2019) and the system of five-yearly carbon budgets.
CO2e
Carbon dioxide equivalent. The seven greenhouse gases added together, each weighted by how much warming it causes compared with CO2.
Conversion factor
A number that turns an activity, such as a kWh or a litre, into kg CO2e. The UK government publishes a new set each June. Read our 2026 factors guide.
CSRD
The EU's Corporate Sustainability Reporting Directive. Since the Omnibus I amendments of 2026 it applies to companies with more than 1,000 employees and €450 million turnover. It uses double materiality and the European Sustainability Reporting Standards (ESRS). UK companies are affected only through large EU operations or EU customers.
DESNZ
The Department for Energy Security and Net Zero, which publishes the UK government conversion factors. Older sets were published by DEFRA and BEIS.
Double materiality
Reporting both how sustainability issues affect a company's finances and how the company affects people and the environment. Used by the EU's CSRD. UK SRS and the ISSB standards use financial materiality only.
Downstream emissions
Scope 3 emissions after your products or services leave you: transport to customers, use of sold products, end-of-life treatment, leased-out assets, franchises and investments. Scope 3 categories 9 to 15. Read our guide to the 15 Scope 3 categories.
Emission factor
Another name for a conversion factor: kg CO2e per unit of activity. For UK reporting, use the DESNZ set for your reporting year. Read our 2026 factors guide.
Equity share and financial control
The two alternatives to operational control for setting your boundary under the GHG Protocol. Equity share counts emissions in proportion to ownership; financial control counts operations whose financial policies you direct.
ESOS
The Energy Savings Opportunity Scheme: a four-yearly energy audit for large UK undertakings. Phase 4 has a qualification date of 31 December 2026 and a compliance deadline of 5 December 2027. Read our ESOS guide.
Evergreen
The NHS sustainable supplier assessment. NHS Supply Chain tenders need Level 1 from 6 April 2026. Read our NHS supplier guide.
F-gases
Fluorinated greenhouse gases, mainly hydrofluorocarbons (HFCs) used as refrigerants in air conditioning, heat pumps and fridges. Leaks are Scope 1 and can be large because these gases have high global warming potentials.
GHG (greenhouse gas)
A gas that traps heat in the atmosphere. Company reporting covers the seven Kyoto Protocol gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride and nitrogen trifluoride.
GHG Protocol
The international standard for measuring and reporting greenhouse gas emissions. It defines Scopes 1, 2 and 3. Read our Scope 1, 2 and 3 guide.
Global warming potential (GWP)
How much warming a gas causes over a set period, usually 100 years, compared with the same mass of CO2. The UK government factors use values from the IPCC's Fifth Assessment Report, in which methane is 28 and nitrous oxide 265.
Green Claims Code
The Competition and Markets Authority's guidance on environmental claims to consumers: claims must be truthful and accurate, clear, complete, fair in comparisons, consider the full life cycle and be substantiated. Read our carbon offsetting guide.
Greenwashing
Making a business, product or service sound more environmentally friendly than it is. Since April 2025 the CMA can fine businesses up to 10% of global turnover for misleading consumers. Read our carbon offsetting guide.
Grey fleet
Employees' own vehicles used for business journeys, usually paid through mileage claims. Reported in Scope 3 category 6, and included in SECR. Read our Scope 1, 2 and 3 guide.
Gross calorific value (gross CV)
A fuel's energy content including heat recovered from condensing water vapour. UK gas bills usually show kWh on a gross CV basis, so use the gross CV factor.
Homeworking emissions
Energy used for heating and equipment when staff work from home. Optional under the GHG Protocol, within Scope 3 category 7. The UK government factors include a factor per full-time-equivalent working hour. Read our guide to the 15 Scope 3 categories.
ICVCM
The Integrity Council for the Voluntary Carbon Market, which sets the Core Carbon Principles: a quality threshold for carbon credits backed by the UK government. Read our carbon offsetting guide.
Intensity ratio
Emissions divided by a measure of business size, such as tonnes CO2e per £1 million turnover. SECR requires at least one.
ISO 14064
The international standards for greenhouse gas accounting. Part 1 covers quantifying and reporting an organisation's emissions, Part 2 projects, and Part 3 verification and validation.
ISO 14068
The international standard for carbon neutrality. First published as ISO 14068-1 in 2023 and revised as ISO 14068:2026 in September 2026. It replaced BSI's PAS 2060 and puts more weight on cutting emissions before compensating for them. Read our carbon offsetting guide.
ISSB
The International Sustainability Standards Board, part of the IFRS Foundation. It published IFRS S1 (general sustainability disclosures) and IFRS S2 (climate) in 2023, the basis of UK SRS. Read our UK SRS guide.
kWh
Kilowatt hour, the unit of energy on most UK electricity and gas bills. SECR reports energy use in kWh.
Lead assessor
A qualified energy professional, on an approved register, who carries out or reviews an ESOS assessment. Not needed if you use under 40,000 kWh or ISO 50001 covers 95% of your energy. Read our ESOS guide.
Location-based Scope 2
Electricity emissions worked out with the average grid factor, whatever tariff you are on. Read our Scope 1, 2 and 3 guide.
Market-based Scope 2
Electricity emissions worked out from your actual tariff. A renewable tariff backed by REGO certificates can count as zero. Read our Scope 1, 2 and 3 guide.
Materiality
Whether information is significant enough to matter to the people using a report. UK SRS asks about financial materiality: whether a sustainability matter could affect the company's prospects.
Near-term target
An emissions reduction target for the next 5 to 10 years, such as a cut by 2030. The SBTi's SME route asks for an absolute Scope 1 and 2 cut of at least 4.2% a year. Read our science-based targets guide.
Net zero
Cutting emissions as far as possible and balancing what is left with permanent removals. PPN 006 asks for a commitment to reach it by 2050. Read our net zero guide for small businesses.
Net Zero Commitment
A short published statement, approved by a director, committing to net zero by 2050 or earlier. The NHS asks for one on contracts of £5 million a year or less. Read our NHS supplier guide.
Operational control
The most common way to decide what is in your footprint: everything your organisation runs day to day, whether you own it or lease it.
PAS 2060
BSI's former specification for demonstrating carbon neutrality, first published in 2010. It has been withdrawn and superseded by ISO 14068. Read our carbon offsetting guide.
Passenger-kilometre
One passenger travelling one kilometre. The unit for rail, bus and flight factors: distance × number of travellers.
PPN 006
The Cabinet Office procurement policy note that asks for Carbon Reduction Plans on government contracts above £5 million a year. It replaced PPN 06/21 in February 2025. Read our Carbon Reduction Plan guide.
Radiative forcing (RF)
The extra warming from flying at altitude beyond the CO2 alone, from effects such as contrails. The UK government publishes flight factors with and without an uplift for it, and recommends including it.
REGO
A Renewable Energy Guarantee of Origin: a certificate proving a megawatt hour was generated from renewable sources.
Residual emissions
The emissions left after a business has cut as far as it can. Under net zero standards they should be small, typically no more than about 10% of the base year, and balanced with permanent removals. Read our net zero guide for small businesses.
SBTi
The Science Based Targets initiative, which sets criteria for corporate emissions targets in line with limiting warming to 1.5°C. Its subsidiary SBTi Services validates targets for a fee. Read our science-based targets guide.
Science-based target
An emissions reduction target consistent with the 1.5°C goal and validated by the SBTi. Don't use the phrase for an unvalidated target. Read our science-based targets guide.
Scope 1
Direct emissions from things you own or control: gas boilers, company vehicles, fuel burned on site and refrigerant leaks. Read our Scope 1, 2 and 3 guide.
Scope 2
Indirect emissions from the electricity, heat and steam you buy. Read our Scope 1, 2 and 3 guide.
Scope 3
All other indirect emissions in your value chain, in fifteen categories, from purchased goods to business travel, commuting and waste. Read our guide to the 15 Scope 3 categories.
SECR
Streamlined Energy and Carbon Reporting: the UK law requiring large companies and LLPs to publish energy use and emissions in their annual report. Read our SECR guide.
Spend-based method
Estimating Scope 3 emissions from money spent, multiplied by average emissions per pound for each industry. Quick but approximate; best used as a first estimate for purchased goods and services. Read our guide to the 15 Scope 3 categories.
Supplier-specific method
Using emissions data calculated by your suppliers and allocated to you. The most accurate way to measure purchased goods and services, once suppliers can provide it. Read our guide to customer data requests.
TCFD
The Task Force on Climate-related Financial Disclosures, whose 2017 recommendations shaped UK climate reporting rules. It was disbanded in 2023 and its work passed to the ISSB. Read our UK SRS guide.
Tonne-kilometre
One tonne of goods moved one kilometre. The unit for freight factors: weight carried × distance.
Transition plan
A company's plan for how it will adapt its business and cut emissions in line with a net zero economy, with targets, actions and timelines. UK SRS S2 asks about it if a company has one. Read our UK SRS guide.
Transmission and distribution (T&D) losses
Electricity lost in the grid between the power station and your meter. Reported in Scope 3, category 3. Read our guide to the 15 Scope 3 categories.
UK ETS
The UK Emissions Trading Scheme, a cap-and-trade scheme that began on 1 January 2021, replacing UK participation in the EU scheme. It covers power generation, energy-intensive industry and aviation, among others.
UK SRS
The UK Sustainability Reporting Standards, UK SRS S1 and S2, published in February 2026 and based on the ISSB standards. Listed companies report against them on a comply or explain basis from 2027. Read our UK SRS guide.
Upstream emissions
Scope 3 emissions from your suppliers and staff before your products or services are delivered: purchased goods, capital goods, fuel and energy, transport, waste, travel, commuting and leased assets. Scope 3 categories 1 to 8. Read our guide to the 15 Scope 3 categories.
Value chain
Everything upstream and downstream of your own operations, from suppliers to customers. Emissions across it are your Scope 3. Read our guide to the 15 Scope 3 categories.
Well-to-tank (WTT)
Emissions from extracting, refining and transporting a fuel before you use it. Reported in Scope 3. Read our guide to the 15 Scope 3 categories.
Woodland Carbon Code
The UK's standard for woodland creation projects that sell carbon units. Only verified Woodland Carbon Units can be used against current emissions; Pending Issuance Units are a promise of future removals. Read our carbon offsetting guide.