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Account holder

The account holder of a British Gas account. The account holder will appear on the front of an energy bill.

Account number

The unique number for your British Gas account. It will be displayed on the front of your bill or statement.

Actual bill

This is a bill based on an actual meter reading (as opposed to an estimated reading). An actual bill will accurately reflect your energy consumption for a defined period. Submitting a meter reading online or the use of smart meters can ensure you receive regular actual bills for your energy use.

Alternative fuel

A fuel which can be used as an alternative to fossil fuels such as oil and coal. Alternative fuels include biofuels, liquefied petroleum gas (LPG) and fuel cells. They are considered to have less environmental impact than fossil fuels.


A unit of electrical current.

Automated Meter Reading (AMR)

Reading or data collected automatically from meters and used for billing purposes. A British Gas smart meter takes remote AMRs for use in actual bills. It also provides data for the analysis of energy consumption across different sites and locations.

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Banking Automated Credit System (BACs)

The electronic transfer of funds. It is just one of the ways you can pay your British Gas bill.

Billing address

The address where bills and invoices are sent. This is not necessarily the address where energy has been used.

Billing period

The period when you will be charged for energy consumption. This is the time between meter readings. It does not refer to the time when the bill was sent or when payment is due to be received. Your billing period will usually be set out in your contract terms (e.g. monthly or quarterly). If no actual meter reading can be obtained, an estimated meter reading will be used for your bill.


Fuels produced from biodegradable material. Biodiesel fuels, for example, are typically made from oils such as soybeans, rapeseed, or sunflowers, or from animal tallow. Biogases can be produced from methane-rich sources such as landfill or sewage.


Device used to generate steam for power and processing or hot water for heating and other purposes. A heating care package such as HomeCare can help you cope with the effects of boiler breakdown.

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Calorific value

The amount of heat generated when a given mass of fuel is completely burned. You can calculate energy use in kilowatt-hours (kWh) by converting it from its calorific value. See "Combined energy Conversion formula" for converting gas units into kWh.

Carbon dioxide (CO2)

A gas produced by fossil fuel combustion as well as other natural processes. It is a normal part of the Earth's atmosphere. CO2 is considered a greenhouse gas as it traps heat into the atmosphere and contributes to the potential for global warming.

Carbon conversion factor

Used to calculate the amount of carbon dioxide (CO2) produced from energy use. According to the Carbon Trust, natural gas has a conversion factor of 0.185, for example, 1,000 kWh of gas used is responsible for the production of 185kg CO2 (0.185 x 1000 kWh).

Carbon footprint

The impact human activities have on the environment. This is measured by the amount of greenhouse gases (usually carbon dioxide) produced by a particular activity.

Carbon monoxide (CO)

Carbon monoxide is produced from the partial combustion of carbon-containing compounds such as gas. It is silent, colourless, odourless and potentially lethal. To prevent against carbon monoxide exposure you should ensure gas appliances, such as your boiler, are installed and serviced regularly by a CORGI registered engineer. 

Carbon Trust

An independent company funded by the government to help the UK move to a low carbon economy. It works with organisations to reduce carbon emissions and develop commercial low carbon technologies.


Centrica is the parent company of British Gas. Centrica is a top 30 FTSE100 company with growing energy businesses in the UK, North America and Europe.

Climate change

Used to indicate significant change from one climatic condition to another. It is also often used to refer to "global warming".

Climate Change Levy (CCL)

A government charge on UK non-domestic fuel introduced in 2001 to encourage customers to use less energy, and contribute to the reduction of carbon dioxide emissions.

Correction factor (CF)

Used to convert gas units into kilowatt-hours (kWh). The correction factor (1.02264) takes into account changes in the volume of gas based on temperature and pressure. See "Conversion formula" for converting gas units into kWh.

Conversion factor

To convert gas units into kilowatt-hours (kWh), two conversion factors are needed: an imperial to metric conversion factor (2.83) and a kilowatt-hour conversion factor (3.6). See "Conversion formula" for converting gas units into kWh.

Conversion formula

Used to convert gas units into kilowatt-hours (kWh). The formula is as follows: gas units used x correction factor (1.02264) x imperial to metric conversion factor (2.83) x calorific value (38.9) divided by kilowatt-hour conversion factor (3.6) = kWh in cubic feet. To calculate a bill, multiply kWh in cubic feet by the unit price in your agreed contract.

Cubic foot (cf)

A unit of measurement for natural gas.

Customer reference number

A unique reference number used for your British Gas account. It will be displayed on the front of your bill or statement, or any other correspondence related to your account (e.g. bill enquiries).

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Dial meter

An older type of electricity meter. The meter display has a series of dials similar to a clock face, except that dials move both clockwise and anti-clockwise.

Diaphragm meter

A gas meter used in small commercial and industrial applications. These meters usually have a long working life and require little maintenance.

Digital meter

An electricity meter with a digital reading display screen.

Distribution network operator (DNO)

One of the 14 regional distributors responsible for maintaining the electrical network in the UK. Any new connection must be organised through your local DNO (British Gas can help you do this). All DNO charges are regulated by OFGEM.

Dual fuel

Indicates the supply of more than one energy type, e.g. gas and electricity.

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Electricity Central Online Enquiry Service (ECOES)

An online service provided jointly by electricity distribution and supply companies. ECOES notifies the relevant suppliers if you switch your electricity supply.


The release of gases into the atmosphere. Often refers to the emission of greenhouse gases, such as carbon dioxide, during fuel combustion.

Energy consumption

Use of energy as a source of heat or power. Your energy consumption will be measured by your gas or electricity meter and you will be billed for the amount you have used.

Energy efficiency

Reducing energy consumption while still maintaining similar levels of output or performance. This is usually achieved by reducing wasted energy or increasing the power efficiency of appliances. There are many things (big and small) you can do to save energy or improve energy efficiency.

Energy management

The monitoring and analysis of energy consumption. This can involve comparing usage, reducing wastage or optimising energy efficiency. British Gas smart meters provide a smart way of managing your energy consumption.

Energy supplier

The company supplying electricity, natural gas, fuel oil, kerosene, or LPG (liquefied petroleum gas) to your home.

Estimated bill

A bill based on an estimated meter reading (as opposed to an actual reading). This bill will reflect your estimated energy consumption for a defined period. Estimated readings are used if we do not have an up-to-date reading or if our meter readers cannot gain access to the premises. Don't forget you can submit your own meter reading online quickly and easily.

EU Emissions Trading Scheme (EU ETS)

A European Union scheme to reduce emissions of carbon dioxide and other greenhouse gases to meet targets set out in the Kyoto Protocol.

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A passageway or pipe for directing products of combustion to the atmosphere.

Fluorescent lights

Usually made from long, narrow, white glass tubes coated with fluorescent material, they use less energy and have a longer life than traditional filament light bulbs.

Fossil fuels

Fuels such as coal, oil and gas which have been formed from the decomposition of ancient plant and animal matter.


The obstruction of the flow of energy from the fire or flue in a boiler. Fouling in boilers can have a significant impact on energy efficiency and potential energy and cost savings.

Fuel cell

A device capable of converting the chemical energy of a fuel directly into electrical energy. The chemicals used are usually very simple, often just hydrogen and oxygen. As the conversion involves an electrochemical process, not combustion, the process is often considered to be more energy efficient and have less environmental impact.

Fuel mix

The mix of fuels used to generate electricity. Electricity can be sourced from a variety of sources – coal, gas, nuclear and renewable.

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Gas Safety (Installation and Use) Regulations 1998

Government regulations controlling the installation and use of gas supplies and appliances. It aims to prevent injury to consumers and the public from carbon monoxide (CO) poisoning, fire and explosion. 

Gas Safety Register

Gas Safety Register is the national watchdog for gas safety in the United Kingdom. You should use a Gas Safety Register engineer for any gas, plumbing, heating or electrical work.

Gigawatt (GWh)

Electrical unit of power equal to one billion watts or one thousand megawatts.

Gigawatthour (GWh)

A unit of measurement for electrical energy equal to one billion watt hours.

Global warming

An increase in the Earth's surface temperature. Global warming has occurred in the past as the result of natural influences, but the term is today most often used to refer to warming resulting from the emissions of greenhouse gases.

Green electricity

Electricity generated from renewable sources which are considered to have a low environmental impact, eg wind or solar power.

Greenhouse gases

Gases such as carbon dioxide which trap heat into the atmosphere and contribute to the potential for global warming. Also known the greenhouse effect.


The electricity transmission system for the UK.

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A material or substance to prevent the flow of heat from one surface to another. Different types of insulation can include foam, loose fill, dead air space, lagging for hot-water pipes or blanket insulation for boilers. Effective insulation can improve the energy efficiency of your home.

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Joule (j)

A unit of measurement for energy equal to one watt-second.

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Kilowatt (kW)

A unit of measurement for power. A kilowatt equals one thousand watts.

Kilowatt hour (kWh)

A unit of measurement for electrical energy, equivalent to the power of one kilowatt operating for one hour. A bill from your current supplier will show your usage in kWh. To calculate your annual consumption, multiply the figure by 12 if you are billed monthly, or by 4 if you are billed quarterly.

Kilovolt ampere (kVA)

A unit of measurement for apparent power, equal to one thousand volt-amperes. To work out your peak energy usage in kVA you will need to phone your energy distribution company.

Kyoto Protocol

The Kyoto Protocol is an agreement made under the United Nations Framework Convention on Climate Change (UNFCCC). The Protocol is the result of negotiations in Kyoto, Japan, in 1997. It sets binding greenhouse gas emissions targets for countries that have signed and ratified the agreement (such as the UK).

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Landfill gas

Gas that is generated from the decomposition of organic material at landfill disposal sites.


The lowest rank of coal used almost exclusively as fuel for power generation. Also known as brown coal.

Liquefied natural gas (LNG)

Natural gas that has been liquefied by reducing temperature or increasing pressure. Its liquefied state means it takes up less space and makes storage and transportation easier.

Liquefied petroleum gas (LPG)

A natural hydrocarbon fuel largely made up of propane and butane. A gas at atmospheric pressure, it is liquefied by reducing temperature or increasing pressure. Its liquefied state means it takes up less space and makes storage and transportation easier.

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Megawatt (MW)

Electrical unit of power equal to one million watts.

Megawatt hour (MWh)

A unit of measurement for electrical energy equal to one thousand kilowatt hours or one million watt hours.

Meter Point Administration Number (MPAN)

A 21 digit number for your electricity supply that will be displayed in a table or a row on your current electricity bill (usually starting with the letter "S").

Meter Point Reference Number (MPR)

A unique number for your gas supply that could be up to 10 digits long. You will find this number on your current gas bill.

Meter reading

Used to determine energy consumption and for issuing a bill for energy usage for a given period. Meter readings can be submitted online or by phone.

Meter Serial Number (MSN)

A unique number used to identify a meter. The MSN will be displayed on the front of most meters.


The small-scale production of energy via mini-wind turbines, solar panels or mini generators.

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National Grid

Owner and operator of the gas and electricity network in the UK.

Natural gas

Gas consisting of methane and ethane. Occurs naturally in the Earth's crust.

Nuclear energy

Energy produced from a nuclear chain reaction of fissionable materials. Generated heat can be used to produce steam, drive turbines and generate electricity.

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Office of Gas and Electricity Markets, the regulatory body for the electricity and gas industries. It protects consumer interests and ensures they get value and choice, by promoting competition and regulating monopolies.

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Parent company

An affiliated company that exercises ultimate control over a business entity, either directly or indirectly. Centrica is the parent company of British Gas.

Photocell switch

A switch which automatically turns lights on and off at dusk and dawn so no timer is needed. Could improve energy efficiency when used in external lighting.

PP10 / PP11 certification

Certification to claim exemption or discount from the Climate Change Levy (CCL). PP10/PP11 certification must be completed and sent to HM Revenue & Customs and the energy supplier.

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Reactive power

The power returned to an electrical source by the reactive components of a circuit. Reactive power is measured in Volt-Amperes-Reactive (VAR). It is considered "unproductive" or "useless" power because the energy is stored in the electrical circuit rather than consumed. This energy is released and returned to the power source rather than used to provide energy to appliances.

Recovered energy

Heat or energy which has been recovered from a process when it would otherwise have been lost. Setting up a power plant to recover lost heat could save wasted energy and cut costs.

Refrigeration plant

A cooling plant used for air conditioning, manufacturing processes and the storage of perishable goods. Configuring a refrigeration plant to run at its optimum efficiency can help save energy.

Renewable energy

Energy from natural sources which can be replaced as it is used. Includes wind, solar and tidal energy. Using energy from renewable resources is considered to have less environmental impact and create a sustainable future for energy supplies. Centrica is currently investing over £750 million in renewable energy sources.

Right to Read

A national campaign promoting the importance of literacy. Right to Read seeks to engage volunteers from our business to become reading partners with 7-11 year old, primary school children. Right to Read is a community initiative supported by British Gas Business employees.

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Smart meters

Meters which send readings automatically and remotely at regular intervals. It means physical meter reads can be less frequent and automatic readings can be used for more accurate, up-to-date billing.

Sodium light

A light, based on an internal sodium discharge, which emits a yellow-orange light. Low pressure sodium lamps are considered to be more energy efficient and less light polluting than conventional lighting and are commonly used for night-time security and street lighting.\

Spray taps

Produce a wide spray of water, offering a greater coverage for easy and quick cleaning. Can save water and energy used for washing.

Standing charge

A fixed cost paid in addition to usage charges for gas and electricity. Standing charges cover costs like meter reading, maintenance, connection to the energy network and, in the case of gas, emergency services.

Supply address

The address where energy is supplied and used. Can be different from the billing address where bills and invoices are sent.

Supply number

A unique reference number identifying the electricity meter at your property. It contains information such as the meter type which may be required by a new supplier. It is usually shown on the front of your energy bill.


Ensuring the long-term and responsible use of natural resources. Includes investing in renewable and alternative energy sources to secure future energy supplies and minimising impact on the environment from fossil-fuel resources.


The process of switching from one energy supplier to another.

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Terawatt (TW)

Electrical unit of power equal to one thousand gigawatts.


The company owning the facilities (e.g. pipeline) by which gas or liquefied natural gas (LNG) is physically transferred to your premises.


A rotary machine which is driven by water, steam, air or gas to generate energy.

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Unit price

The price paid per unit of energy used (e.g. in kilowatt hours). The unit price includes costs such as transportation but excludes standing charges, government taxes such as VAT or the Climate Change Levy, or any other third party costs.

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Value Added Tax (VAT)

A government tax charged on most  business-to-consumer transactions in the UK, including electricity and gas supplies.


A unit of electric potential. Electrical outlets in homes are usually measured in volts.

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Warm Home Discount

The Warm Home Discount Scheme, run by the Government and energy suppliers, provides a one-off payment towards electricity bills for some of the most vulnerable households in Britain

Waste recycling

The collection of waste materials for re-use. This means that fewer new products and consumables need to be produced, saving raw materials and reducing energy consumption. British Gas is set recycling targets by the Centrica Group.

Water power

A renewable energy source where energy is generated from a water source, such as hydro-electric, wave or tidal power.

Watt (W)

A unit of electrical measurement equal to one ampere under a pressure of one volt.

Watthour (Wh)

A unit of electrical measurement equal to one watt of power supplied to, or taken from, an electric circuit steadily for one hour.

Wind farm

A group of wind turbines (up to several hundred) for generating electrical energy. They are erected in areas of high and steady wind strength, both offshore and onshore. Centrica has invested in two operational wind farms onshore in Scotland (Glens of Foudland and Braes of Doune) and is currently investing in six offshore wind farm developments (Barrow, Lynn, Inner Dowsing, Lincs, Race Bank and Docking Shoal).

Wind power

Energy generated by using wind to turn turbines and generate electricity. Wind energy is pollution-free and renewable and is considered to be the most economically viable and scaleable renewable energy source.

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