Gas and electricity glossary

Confused by the terminology on your energy bill? Read our utilities glossary, then compare gas and electricity price plans to see if you can save money.

Actual bill: A bill based on an actual meter reading, as opposed to an estimated gas and electricity reading.

This is often denoted on an energy bill by a capital 'A' for actual or 'E' for estimated.

If a meter reading is followed by an 'A', this will mean that a bill accurately reflects your energy consumption.

It is generally recommended that homeowners provide an actual reading to their gas and electricity supplier every quarter.

Alternative fuel: Any fuel that does not come from original sources such as oil or coal. This can include biofuels or liquefied petroleum gas (LPG).

Ampere: An ampere - which can be shortened to amp - is a unit of electrical current.

Carbon offsetting is a way in which you can balance out your carbon emissions by sponsoring projects or schemes designed to reduce carbon emissions

Billing period: The length of time that you're being charged by your supplier for using gas and electricity.

Biofuels: A type of fuel that's derived from living things, or waste. Fuel that comes from these sources is seen as a way of reducing greenhouse gases. There are many different types of biofuel used in the UK, the main two are biodiesel and bioethanol.

BRFC: The UK's system for rating the energy efficiency of windows. This guide uses an A-G rating system which can be used to help homeowners make more informed choices about their windows.

Calorific value (CV): This is a term that is used to describe how much heat is generated when a volume of gas is burned away. The calorific value of your gas will always be displayed on your energy bill. If you'd like to know more about how a calorific value (CV) is calculated and used, the National Grid is a good place to start.

Carbon footprint: This describes the impact of the carbon dioxide emissions (CO2) that any person, product, business or event can have on the environment. It's measured in tonnes and once you know the carbon footprint of your home, business or any activity, you can then look at ways of reducing your footprint.

Carbon offset: Carbon offsetting is a way in which you can balance out your carbon emissions by sponsoring projects or schemes designed to reduce carbon emissions.

Carbon Trust: An organisation dedicated to helping businesses, the public sector and governments to deliver a low-carbon economy. It provides ways for businesses to reduce carbon emissions, by developing low-carbon technologies and solutions.


Corgi: See Gas Safe Register.

Dual fuel: Dual fuel means that your gas and electricity are both supplied by the same provider.

Economy 7: This is an electricity tariff that means you pay a different price for your electricity at different times of the day. On this tariff, the electricity you use will be cheaper for seven hours during the night - referred to as off-peak times.

Economy 10: Similar to Economy 7, this is designed to be used with high thermal mass heating such as storage heaters, underfloor heating, and is also used with electrical boilers driving radiators or water-based heat stores. Unlike Economy 7, Economy 10 tariffs provide 10 hours of off-peak heating split between night, afternoon and evening.

Energy consumption: This is simply the amount of energy you use.

Energy efficiency: This refers to using less energy - a good example of energy efficiency would be installing energy-saving light bulbs, which use less energy to achieve the same result. The efficiency of household appliances can now be measured according to the European Union efficiency label which rates appliances from A (most efficient) to G (least efficient).

Gas Safe Register: The national watchdog for gas safety in the UK, replacing the role formerly played by Corgi. All gas installers and maintenance engineers should be registered with the scheme.

Meter Point Administration Number (MPAN): A 21-digit number that is unique to your property and can be found on your electricity bill. You will need to quote this if you want to change supplier. The gas equivalent is a Meter Point Reference Number (below).

Meter Point Reference Number (MPRN): The gas equivalent of an MPAN, which can be found on your gas bill. It is unique to your property and does not change, even if you switch your gas provider.

The government has set a target that all homes should have a smart meter by 2020

Ofgem: The Office of Gas and Electricity Markets. Ofgem regulates the companies who provide gas and electricity in the UK.

Ofgem was formed in 1999 and its key responsibilities include setting price controls and protecting consumers' interests in the provision of gas and electricity.

The Ofgem Confidence Code governs independent energy price comparison sites, like's partner

Prepayment meter: A prepayment energy meter enables households to pay for their gas and electricity up front. Payments can be made using tokens, smartcards or keys that can be topped up. Prepayment meters can help you budget your bills more effectively as all gas and electricity payments will be made up front. Prepayment meters are often found in rental properties as landlords have the security of knowing that tenants won't fall behind in their gas and electricity payments.

Smart meters: Smart meters allow you to pay only for the gas and electricity that you actually use. It eliminates the need for estimated readings as your meter reading is automatically sent to your energy supplier. The government has set a target that all homes should have a smart meter by 2020.

S-Number: See Meter Point Administration Number (MPAN).

Solar power: This is the conversion of sunlight into electricity. If you power your home through solar power, it can help to minimise the cost of bills and also help to reduce your carbon footprint.

Standing charge: If you have a standing charge on your bills, this means you pay a fixed amount for the amount of energy you use and the supply. If you have NSC (no standing charge) on your bill, this means that you don't have a standing charge, you pay for the energy that you actually use, but the supply cost is factored into the cost of each unit.

Supply number: See Meter Point Administration Number (MPAN).

Tariff: This is the amount you pay for your gas and electricity.

Tiers: This describes how you are charged for your gas and electricity. You may have one rate for a certain amount of energy and then a different rate will be charged for any additional units of gas and electricity that you use.

Wind power: Converting wind into a form of energy, for example using wind turbines to produce electricity. In the UK there are numerous wind farms, which are a group of wind turbines placed together to increase the amount of electricity produced.

By Lynsey Walden