Climate Change and Air Quality Strategy

Last updated: 30 September 2021

12. Glossary

Base year - A historic datum (a specific year or an average over multiple years) against which an organisation’s emissions are tracked over time

Base year emissions - GHG emissions in the base year.

Base year emissions recalculation - recalculation of GHG emissions in the base year to reflect a change in the structure of the company, or to reflect a change in the accounting methodology used. This ensures data consistency over time, i.e., comparisons of like with like over time.

Biodegradable – capable of being broken down into naturally occurring substances by bacteria and other naturally occurring agents.

Biofuels - Fuel made from plant material, for example wood, straw and ethanol from plant matter

Boundaries - GHG accounting and reporting boundaries can have several dimensions, i.e. organizational, operational, geographic, business unit, and target boundaries. The inventory boundary determines which emissions are accounted and reported by the company.

Business as Usual (BAU) - The emissions pathway or scenario if no further mitigation action is taken to reduce emissions.

Carbon sequestration - the uptake of CO2 and storage of carbon in biological sinks.

Carbon neutral - The emissions pathway that will ensure achievement of net zero carbon emissions pathway by 2050 (or other specific date).

Co-generation unit/Combined heat and power (CHP) - a facility producing both electricity and steam/heat using the same fuel supply.

CO2 equivalent (CO2-e) - the universal unit of measurement to indicate the global warming potential (GWP) of each of the six greenhouse gases, expressed in terms of the GWP of one unit of carbon dioxide.

Combustion - or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products.

Direct emissions – emissions from sources that are owned or controlled by the reporting organisation.

Emissions - the production and discharge of something. In this document it refers to the release of pollutants into the atmosphere (GHGs and air pollutants relevant to national air quality objectives)

Emission factor - A factor allowing GHG emissions to be estimated from a unit of available activity data (for example tonnes of fuel consumed, tonnes of product produced) and absolute GHG emissions.

Energy efficiency projects – interventions resulting in less energy being used to produce the same result/work (for example insulating walls and roof voids, LED lighting retrofits).

Fossil fuels – non-renewable/finite (not being replenished or being replenished very slowly) resources formed as a result of geologic processes acting on the remains of organic matter. Fossil fuels contain carbon and include coal, petroleum, natural gas, oil shales, bitumen, tar sands, and heavy oils.

Fossil fuel derivatives – products made from the processing of fossil fuels. Plastic is made from fossil fuel derivatives.

Fuel poverty - A household is considered to be fuel poor if they have required fuel costs that are above average, or if they were to spend that amount they would be left with a residual income below the official poverty line.

Fugitive emissions - emissions that are not physically controlled but result from the intentional or unintentional releases of GHGs. They commonly arise from the production, processing transmission storage and use of fuels and other chemicals, often through joints, seals, packing, gaskets, etc.

Geothermal energy - heat that comes from the sub-surface of the earth. It is contained in the rocks and fluids beneath the earth's crust.

Green power - a generic term for renewable energy sources and specific clean energy technologies that emit fewer GHG emissions relative to other sources of energy that supply the electric grid. Includes solar photovoltaic panels, solar thermal energy, geothermal energy, landfill gas, low-impact hydropower, and wind turbines.

Greenhouse gases (GHGs) - GHGs are the six gases listed in the Kyoto Protocol: carbon dioxide (CO2); methane (CH4); nitrous oxide (N2O); hydrofluorocarbons (HFCs); perfluorocarbons (PFCs); and sulphur hexafluoride (SF6).

GHG capture - collection of GHG emissions from a GHG source for storage in a sink.

GHG credit - GHG offsets can be converted into GHG credits when used to meet an externally imposed target. A GHG credit is a convertible and transferable instrument usually bestowed by a GHG program.

GHG/carbon offset - offsets are discrete GHG reductions used to compensate for (i.e., offset) GHG emissions elsewhere, for example to meet a voluntary or mandatory GHG target or cap.

GHG removal - absorption or sequestration of GHGs from the atmosphere.

GHG/carbon sink - any physical unit or process that stores GHGs; usually refers to forests and underground/deep sea reservoirs of CO2.

GHG source - any physical unit or process which releases GHG into the atmosphere.

Global Warming Potential (GWP) - a factor describing the radiative forcing impact (degree of harm to the atmosphere) of one unit of a given GHG relative to one unit of CO2.

Indirect GHG emissions - emissions that are a consequence of the operations of the reporting company, but occur at sources owned or controlled by another company.

Inorganic - not consisting of or deriving from living matter.

Intergovernmental Panel on Climate Change (IPCC) - international body of climate change scientists. The role of the IPCC is to assess the scientific, technical and socio-economic information relevant to the understanding of the risk of human-induced climate change (

Kyoto Protocol - a protocol to the United Nations Framework Convention on Climate Change (UNFCCC). It requires countries listed in its Annex B to meet reduction targets of GHG emissions relative to their 1990 levels during the period of 2008–12.

Local Enterprise Partnerships (LEP) - business led partnerships between local authorities and local private sector businesses.

Naturally occurring – exist in nature without artificial aid.

Net zero carbon - the amount of total emissions released on an annual basis averages to be zero or negative i.e. the amount of emitted emissions balanced with those removed or offset.

Renewable energy – energy derived from renewable (naturally replenishing) sources (for example sun, wind, wave, geothermal).

Recycling - the process of converting discarded materials into new materials and objects.

Recyclable – capable of being recycled.

Scope 1 emissions - emissions resulting from the combustion of fuel (for example petrol, diesel or gas) within an area/by an organisation.

Scope 2 emissions - emissions coming from the electricity that is used within the area/by an organisation.

Scope 3 emissions - emissions associated with the goods and services that are produced elsewhere but imported and consumed within the area/by an organisation.

Small and medium sized enterprises (SMEs) - Non-subsidiary, independent firms which employ fewer than 250 employees typically.

Sustainable energy projects – a general term referring to both renewable energy and energy efficiency projects.

Telematics – technology in vehicles which allows information on the movement of a vehicles to be recorded and transferred to other systems, so that it may be analysed

ULEV – Ultra low emission vehicles. A low emission car or van that emits 75g/km CO2 or less. ULEVs include pure electric vehicles, electric range-extender vehicles, and plug-in hybrids (PHEVs).

UK Climate Change Committee - Independent, statutory body established under the 2008 Climate Change Act, to advise the UK Government on progress and action to reduce GHG emissions.