In this guide we take the confusion out of the most common energy abbreviations and terminology by explaining them in Plain English.
We know that any conversation about energy, renewable technology and climate change can be full of confusing terms.
We’ve created this jargon buster to explain the most common words, abbreviations and measurements you might come across. These should be useful for you if you’re:
We’ve formatted our glossary in alphabetical order as a table, with a description of each term in Plain English. We’ll also link to any relevant guides that explore the topic in more depth.
These are some of the most common abbreviations you’ll come across on our website:
| Term | Definition | Plain English explanation |
|---|---|---|
| BUS | Boiler Upgrade Scheme | A UK Government grant of up to £7,500 to help pay for a heat pump or biomass boiler in England and Wales. |
| CCF | Concessional Consumer Financing | Low or no-interest loans for energy saving improvements, usually with longer repayment periods. |
| CO2 | Carbon dioxide | One of the most common greenhouse gases, produced by all living things as well as burning fossil fuels. |
CO2e | Carbon dioxide equivalent | A way to measure all greenhouse gases in terms of how much CO2 they equal. |
| COP | Conference of the Parties | The United Nation’s yearly climate summit where countries meet to make decisions on climate change. |
| CoP | Coefficient of Performance | A measure of how efficient a heat pump is, usually tested under laboratory conditions. |
| DNO | Distribution Network Operator | The local company that owns the electricity network and cables, responsible for transporting power to and from buildings. |
| ECO | Energy Company Obligation | A UK Government scheme that helps people with low incomes make their homes warmer and use less energy. |
Energy transition | Energy transition | The shift from fossil fuels to renewable energy sources like solar, wind and hydroelectricity. |
| EPC | Energy Performance Certificate | A rating that shows how energy efficient a building is. |
| ESS | Energy Storage Systems | Technology that stores energy to for it to be used later, like batteries. |
| EV | Electric vehicle | A car or van powered by electricity rather than petrol or diesel. |
| FiT | Feed-in Tariff | An old tariff that paid people and businesses to export electricity. It’s since been replaced by the Smart Export Guarantee. |
| GBIS | Great British Insulation Scheme | A UK Government scheme to help people get free or discounted insulation. It closed to new applicants in October 2025. |
| GHG | Greenhouse gases | Gases that trap heat in the Earth’s atmosphere, like carbon dioxide and methane. |
| GW | Gigawatt | A unit of power equal to 1 billion watts, typically used to describe the output of large power plants or the total electricity generation capacity of a country. |
| ICE | Internal Combustion Engine | Traditional engines that burn petrol or diesel. |
| IoT | Internet of Things | A network of devices connected to the internet that can communicate with each other, like smart meters and thermostats. |
Just transition | Just transition | Shifting to using renewable energy as a society while ensuring fairness for all those who are affected. |
| kW | Kilowatt | A unit of power equal to 1,000 watts. It measures how fast an appliance uses energy. |
| kWh | Kilowatt-hour | Measures the total energy used over time, for example, by a 1,000-watt appliance running for one hour (1kWh). |
| kWp | Kilowatt peak | A unit that measures the maximum power a solar panel system can produce. |
| kWth | Kilowatt thermal | A unit of power used to measure how fast a system can generate heat. |
| LCA | Lifecycle Assessment | A method used to work out the environmental impact of a product from raw material extraction to disposal. |
| MCS | Microgeneration Certification Scheme | A UK quality assurance programme that certifies renewable energy products and installers to meet industry standards. We always recommend using MCS-registered installers to ensure quality, safety, and eligibility for support. |
| Micro-CHP | Micro combined heat and power | A system that generates heat and electricity from a single source where, usually, electricity is a by-product. |
| MW | Megawatt | A unit of power equal to 1 million watts (1,000kW), often used for large-scale power plants, wind farms, or electricity grids. |
PV | Photovoltaic | The technology used by solar panels that converts sunlight into electricity. |
| REC | Renewable Energy Certificate | A document that proves electricity was generated from a renewable source, often used by businesses for sustainability reporting. |
| SAP | Standard Assessment Procedure | The UK Government’s official methodology for assessing and rating the energy performance of homes, supporting Building Regulations and Energy Performance Certificates. |
| SCoP | Seasonal Coefficient of Performance | A measure of how efficient a heat pump is, taking seasonal temperature changes into account. |
| SDG | Sustainable Development Goal | One of 17 goals used by the United Nations to protect the planet and society. |
| SEG | Smart Export Guarantee | An export tariff available in Great Britain that pays people for the electricity they export to the grid. |
| SVR | Standard Variable Rate | The default tariff for an energy supplier, where the price per unit of energy can change over time. |
| UNFCCC | United Nations Framework Convention on Climate Change | An international treaty that provides the foundation of global climate negotiations and sets targets for reducing greenhouse gases. |
| U-value | U-value | Measures the rate of heat transfer through a wall, window or roof, showing how effective a material is at reducing heat loss. The lower the U-value, the more effective it is. |
| W | Watt | The unit of power that measures how fast energy is used or produced at a specific moment in time. |
Power is measured in watts, kilowatts, megawatts or gigawatts. Meanwhile, total energy used over time is measured in watt-hours, kilowatt-hours, megawatt-hours, or gigawatt-hours. Different scales are used depending on the context:
We’ll regularly review and update this list with new terms. If there’s an abbreviation or bit of jargon you don’t see here, let us know!
Energy Saving Trust is authorised and regulated by the Financial Conduct Authority (716195). It does not provide or run the financial advice, products or services mentioned on this page, which is intended for information purposes only and does not constitute financial advice.
New energy labels for tumble dryers came into effect in Northern Ireland on 1 July 2025. Here’s what you need to know.
What is Measure, Plan, Act and how can it help get you to corporate net zero?
You should give your energy supplier at least 48 hours’ notice before you move. We walk you through what to do before…
Last updated: 20 March 2026
Get free, monthly energy advice you can trust
Subscribe
