Energy glossary

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Active Power

Refers to the rate at which power is produced or transferred using electrical energy. Active power rate is measured in kW and MW.

Agreed Capacity

Refers to the amount of electrical load supplied to a property, as agreed with the local Distribution Network Operator and specified in the energy contract.

Alternative Fuels

Refers to non-conventional fuels derived from natural gas or biomass materials. Ethanol, propane, methanol and compressed natural gas are some examples of alternative fuels.

Annual Quantity (AQ or AAQ)

The annual quantity of gas consumed measured in kilowatt hours (kWh)

Assistance for areas with high electricity distribution costs (AAHEDC)

These costs were introduced by the Government to reduce the distribution costs to consumers in the North of Scotland.

Automated meter reading (AMR)

Automatic Meter Reading, or AMR, is the term given to a system that provides automatic meter readings remotely, without the need for a physical visit. Such systems use mobile telephone technology to transfer consumption data, facilitating accurate billing for business users. Consumption is recorded every 30 minutes.

Available Supply Capacity (ASC)

Also known as Agreed Capacity (see above), Available Supply Capacity (ASC) is the agreed electrical load of a single given property, as established by the Distribution Network Operator (DNO).

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Balancing Services Use of System Charges (BSUoS)

Charges that are paid by electricity suppliers based on the energy taken from or supplied to the National Grid system in each half-hour settlement period.

Base Load

Refers to the lowest level at which electricity demand never drops below. For example, if a business’ electricity demand never drops below 300 kVa, the site would have a base load of 300kVa.

BCM (or bcm)

Large scale units of measurement of gas volume - Billion cubic meters.

Bear Market

A market in which prices generally are declining. An energy trading term.

Billing Period

The period of time for which you are charged for using gas and electricity by your business energy supplier.


Also known as biofuels or bioenergy, biomass refers to energy obtained from organic matter, either from a specialist plant or indirectly from commercial, industrial or agricultural products. Biomass is considered a carbon neutral energy source, given that the carbon dioxide released during generation is balanced by the CO2 absorbed by plants as they grow.

British Electricity Trading And Transmission Arrangements (BETTA)

The British Electricity Trading And Transmission Arrangements, or BETTA, refers to the UK’s single wholesale electricity energy market. Introduced in 2005, BETTA replaced the, now defunct, NETA (New Electricity Trading Agreements) scheme.


A business with the primary function of bringing together the buyers and sellers of energy. Sometimes referred to as a third party intermediary or TPI.

Building Energy Rating (BER)

Launched in 2007, the Building Energy Rating (BER) is a form of legislation in which the ventilation and heating requirements of new and existing commercial buildings are judged against a naturally ventilated building benchmark. The rating is displayed on a scale of A to G, with A being the most energy efficient and G the least.

Bull Market

A market in which prices generally are rising, opposite of a bear market. An energy trading term.

Business Rates

Business rates are a tax levied on properties used for commercial businesses. Learn what the rateable value is on your property with our handy guide.

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Calorific Value

The calorific value (CV) is a measurement of the amount of energy contained in the gas. CV is usually quoted in megajoules per cubic metre (MJ/m3). Gas delivered to your premises will have a CV of between 37.5 MJ/m3 and 43.0 MJ/m3.This is continually measured by the gas transporters for each Local Distribution Zone and passed to your gas supplier daily. It is a legal requirement to to include the CV on invoices.

Capacity Charge

A charge set by the local Distribution Network Operator (DNO), to cover investment, maintenance and repairs to the network. The charge is dependent on the Agreed Capacity of the property, and can also be called the Availability Charge.

Carbon Capture and Storage (CCS)

Carbon Capture and Storage is a three-step process in which CO2 is removed from air before or after the combustion of fossil fuels. Step 1 is capturing CO2 from the emissions produced by power stations; step 2 is transporting the CO2 to storage points, usually by pipeline; and step 3 is storing the carbon safely, often in depleted oil and gas fields.

Carbon Reduction Commitment (CRC)

Introduced by the UK government, the Carbon Reduction Commitment (CRC) is an emissions trading scheme for large corporations that are not eligible for the EU Emissions Trading. The scheme is mandatory, and applies to businesses and organisations including banks, universities, large hospitals, local authorities, central government departments and occasionally large offices.

Carbon Trading

Carbon trading controls carbon emissions by putting a limit on total emissions from certain activities or sectors. This puts a price on carbon and creates a market whereby participants can trade their carbon allowances. Allowances are initially allocated, perhaps through a free distribution or through an auction. The carbon price provides an economic incentive to reduce emissions and allows for any reductions to take place at the lowest cost across the scheme. The limit on total emissions is adjusted periodically.

Citizens Advice Bureau

Citizens Advice consumer service which offers consumer advice and information.

Climate Change Levy (CCL)

CCL is designed to encourage energy savings and the reduction of carbon dioxide emissions. The tax is imposed on all UK businesses and applies to the use of certain fuels and electricity in industry, commerce, agriculture and public administration.

Combined Half Hourly (HH) Data Charge

The cost of collecting and handling data from half hourly (HH) meter readers.

Commodity Charge

A charge levied by National Grid on the quantity of gas transported throughout the network

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Daily Contract Quantity (DCQ)

The contracted amount of gas supplied daily to a site or to a terminal.

Daily Meter (DM)

Businesses whose annual quantity (consumption) is greater than 58,600,000 kWh (or 2 million therms per annum) must be daily metered. This is a mandatory requirement.

Data Collector (DC)

An accredited organisation appointed by an energy supplier to carry out data collection for half-hourly AMR metering systems. It’s the DC’s responsibility to retrieve and validate meter reading consumption data, before passing this on to the supplier.

Data Logger

A data logger is a device used to record gas consumption and to transmit meter readings remotely — for more accurate gas billing.

Deemed Contract

A contract which applies to a business energy customer at a premises without a signed and written contract for its supply. Deemed contracts will have a default rate for supply.

Department of Energy and Climate Change (DECC)

The Department of Energy and Climate Change (DECC) was created in October 2008, bringing together energy policy previously with BERR and Defra.

Distribution Network (DN)

(Gas);The operator responsible for the operation and maintenance of the local transmission system. There are currently eight DNs in the UK.

Distribution Network Operator (DNO)

(Power);The operator of one of the 14 regional distributors responsible for maintaining the electrical network in the UK. All DNO charges are regulated by Ofgem.

Distribution Use of System (DuoS) Charges

These are the costs associated with the Distribution Network which are levied by the regional Distribution Network Operators.

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Electricity Pool

Refers to the trading of electricity between generators, suppliers and, on rare occasions, large electricity customers.

Electronic Data Interchange (EDI)

The Electronic Data Interchange, or EDI, transfers large quantities of billing data through a secure channel, and gives customers the option to receive their bill in a specific format. This is often used by large organisations looking to integrate their energy billing into their own budgeting system.

Emissions Trading Scheme (ETS)

The Emissions Trading Scheme is an EU-wide programme used for the trading of carbon dioxide and other greenhouse gas emissions, as well as carbon credits.

Energy Charter Treaty (ECT)

The Energy Charter Treaty is a multilateral framework for energy cooperation, unique under international law. The treaty is designed to promote energy security through the use of open and competitive energy markets, while adhering to the ethics of sustainable development.

Entry Point

The point at which gas is delivered into the National Transmission System, i.e. the gas terminal.

Estimated Annual Consumption (EAC)

This is the estimated electricity that will be consumed on an annual basis.

Estimated meter reading

Estimated meter readings are done by energy suppliers when they haven’t got an actual meter reading. This bill will reflect your estimated energy consumption for a defined period. By taking regular meter readings, your supplier will bill you more accurately.

European Emissions Trading Scheme

The European Emissions Trading Scheme operates in 31 countries, and forms the cornerstone of the EU’s climate change policy. The scheme works on the ‘cap and trade’ principle, whereby within the cap, organisations receive and purchase emissions allowances and trade them with one another as required.

Exit Zone

A geographical area in which a gas off-take and supply point is located.

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Feed-in Tariffs

Payments made by FIT licensed electricity suppliers to energy users who generate their own electricity They are designed to encourage the adoption of renewable energy sources and to help accelerate the move toward grid parity.

Fixed Charge

A charge levied by the energy supplier, which is separate to the standing charge. A fixed charge is normally billed on a daily, monthly or quarterly basis.

Flexible Energy Purchasing

Flexible energy purchasing, whether it be for gas or electricity, gives the customer the option to buy or sell energy at any time — making it possible to take advantage of fluctuations in the wholesale price of gas and electricity.

Fossil Fuel Levy (FFL)

The Fossil Fuel Levy was introduced to cover the cost of decommissioning nuclear generating plants in the UK. In England and Wales, the levy is set at a rate of 0.3%. In Scotland, where the FFL is referred to as the Scottish Renewable Order (SRO), the rate is set at 0.8%.

Fuel Mix Disclosure (FMD)

Launched in March 2005, the Electricity (Fuel Mix Disclosure) Act stipulates that electricity suppliers must provide customers with information on the mix of fuels used to produce the electricity supplied to them. This information, alongside other environmental statistics, is published on a customer’s bill.

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Gas Day

Gas companies may define the start and end of their “Gas Day” in terms of 06.00 to 06.00, 08.00 to 08.00 or 12.00 to 12.00. This is very important contractually.

Gas Distribution

The transportation of gas through low pressure pipeline network(s).

Gas Substation

A site on a business customer’s premises where gas pressure is reduced from mains pressure to a medium or low pressure for use on site.

Gas Transporter (GT)

A Gas Transporter (GT) is responsible for maintaining the gas supply network.

Gas-fired Generation

A third of the UK’s electric power is generated in gas-fired power stations, and the process is considered the most efficient option for large-scale electricity production. Though gas-fired generation does release CO2, the emissions are much lower than burning traditional fossil fuels, like coal.

Giga Watt (GW)

A Giga Watt, often represented as GW, is the equivalent to 1,000 Mega Watts.

Greenhouse Gas Protocol

The Greenhouse Gas Protocol, commonly referred to as GHG, is the primary standard for emissions reporting. Developed by the World Resources Institute, the GHG protocol has become the corporate standard for carbon footprint calculation — making it easy for suppliers and customers to report the emissions of a specific site.

Grid Supply Point (GSP)

Grid Supply Point (GSP) refers to the point at which energy is taken from the National Grid transmission system, before being transported into a local distribution system.

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Half Hourly (HH) Meters

A communication device connected to a meter, which a data collector can use to remotely collect half-hourly consumption data.

Half Hourly Data (HHD)

Refers to the data received from a Half Hourly Meter. This half-hourly consumption data is normally presented to the customer in a spreadsheet, allowing them to review their average consumption over a set period.

Heat Rate

The energy input per unit of time, normally expressed in kWh/h or BTU/h.

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Independent Public Gas Transporter (IGT)

An independent firm responsible for maintaining regional gas supply network/s.


A material used to stop, reduce or interrupt the flow of electricity.

Integrated Pollution Prevention and Control (IPPC)

The IPPC was introduced to minimise pollution from point sources across the EU.

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Kilowatt (kW)

A standard unit of electrical power equal to one thousand watts, or to the energy consumption at a rate of 1000 Joules per second. A bill from your current supplier will show your usage in kWh.


Kilowatt-hour is the unit of energy used in the gas industry as a basis for setting charges.

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Large Supply Point

Refers to a supply point in which the actual quantity consumption is equal to or exceeds 732,000 kWh, or 25,000 therms per annum.

Liquefied Natural Gas (LNG)

Liquefied Natural Gas, or LNG, forms when natural gas is cooled to a temperature of -160°C at normal atmospheric pressure. This condenses the gas, making it easier to transport.


Load refers to the amount of energy supplied to a specific supply point, or the amount of energy required by the electricity customer.

Load Management

Large electricity supply sites, which are flexible about when and how they use electricity, use load management to schedule their production patterns to take advantage of reductions in the price of pool electricity. Consumers that are able to manage their electricity load in line with the National Grid’s Triads could see sizeable reductions in the price they pay for energy.

Local Distribution Zone (LDZ)

The Local Distribution Zones describes the geographic area in which a network of pipes deliver gas to most of the Customer sites in the area e.g. South Wales, London. This network may be connected to private networks owned IGTs.

Low Carbon Building Programme (LCBP)

Introduced by the UK government in 2006, the Low Carbon Building Programme provides monetary funding for businesses interested in stalling on-site micro-generation technologies, as well as other low-carbon appliances.

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Maximum Annual Quantity (MAQ)

The Maximum Annual Quantity (MAQ) represents the total amount of natural gas to be delivered to a customer’s site during the contracted year.

Maximum Demand

Maximum Demand refers to the peak energy usage (in kWh) of a single Half Hour cycle during a calendar month, or between two scheduled meter reads.


Electrical unit of power equal to one million watts. Standard measure of electric power plant generating capacity.


Means a meter which conforms to s17(1) of the Gas Act and is of an appropriate type for registering the quantity of gas supplied;

Meter Asset Manager (MAM)

This is defined in the Standard Conditions of Gas Supply Licence as a person or a class or description of persons possessing the expertise satisfactorily to design, install, commission, inspect, repair, alter, reposition, remove, renew and maintain the whole or part of the Supply Meter Installation as defined in Section M, paragraph 1.2 of the Network Code as at 1 August 2007; or a person whose staff have such expertise.

Meter Point

This is the point where a meter is, or will be, connected to the gas distribution network.

Meter Point Administration Service (MPAS)

The organisation responsible for assigning the Meter Point Administration Number to all electricity and gas supply points in the UK. For more information, visit

Meter Serial Number

The Meter Serial Number is an identification number assigned to every gas and electricity meter point in the UK, across both corporate and domestic energy customers. The Meter Serial Number may contain a combination of both letters and numbers, and can normally be found stamped, ingrained or attached to the front of the meter box.


Refers to the small-scale generation of electricity, often by the business themselves. Considered a highly-renewable energy source, micro-generation can take many forms, including solar panels or domestic wind turbines.

Million Cubic Meters (MCM)

Million Cubic Meters is a unit of gas measurement, with 1 MCM equating to approximately 360,000 therms.

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National Balancing Point (NBP)

National Balancing Point refers to the point at which wholesale gas is traded within the UK.

National Grid

National Grid own and manage the UK’s primary gas and electricity transmission systems. All electricity generated in the UK is transmitted to the National Grid before being transferred to the local distribution network. National Grid is responsible for transmitting electrical power from the generator to local distribution networks.

National Transmission System (NTS)

The National Transmission System, or NTS, is a network of high-pressure gas pipelines supplying gas to around forty power stations and large industrial users from natural gas terminals. The National Grid owns the NTS, and is responsible for supplying gas to the gas distribution companies.

Non-Half Hourly Meters

Non-Half Hourly Meters require the user, or their energy supplier, to manually read the device to obtain a meter read. Non-Half Hourly Meters are normally reserved for domestic users, or small business users.

Non-Daily Metered Supply Point

A Non-Daily Metered Supply Point is a Supply Point which is required to provide meter readings on a non daily basis, e.g monthly, quarterly or yearly basis.

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This is the process by which the Old Supplier can object to the transfer and block it.


The period during a day, week, month or year when the load being delivered by a gas system is not at or near the maximum volume deliverable by that system.


The Office of Gas Electricity Markets (OFGEM) is the independent government agency who regulates the onshore gas and electricity industries in Great Britain.


Gas or electricity removed from the network to meet customer demand.

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Pass Through Charges

Pass Through Charges are items which may appear on a customer’s energy bill, covering the cost, if relevant, of any third party services involved in the energy supply chain.

Peak Demand

Peak Demand refers to the maximum demand for electricity placed on the National Grid on any given day or over any time period.

Percentage Day

Refers to the percentage of electricity used during the daytime versus the night-time. Suppliers use this information to generate and assign the customer profile.

Power Factor

Used to gauge how efficiently electricity is utilised across a site, particularly when using certain types of industrial equipment and machinery — which could reduce the capacity of the local network to supply power. DNOs often apply Power Factor charges to large consumers who use electricity inefficiently.

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A ratchet is a commercial penalty charge applied to any daily metered supply point which exceeds the agreed daily capacity during the winter period (October to May). Ratcheting is used to deter large energy consumers against setting their daily capacity below what is actually required during the winter period.

Find out more about ratchet charges


OFGEM is responsible for regulating the UK’s gas and electricity industries. Energy regulators have the power to enforce legislation and regulations on market participants — helping to ensure a fair and competitive market for energy customers.

Renewable Energy Certificates

Renewable Energy Certificates, also known as RECs and ‘green certificates’, represent the power produced from internal energy projects, usually by large industrial businesses. RECs can be traded, bought or sold, and are separate to commodity electricity.

Renewable Obligation (RO)

Renewable Obligation (RO) is the government’s primary initiative for the promotion of renewable energy practices. The programme is mandatory under the Climate Change Levy exemption scheme, and means that all electricity suppliers must contribute a certain amount of their electricity sales revenue from accredited renewable sources.

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Serial number

The manufacturer’s number stamped on each meter.

Service Industry Code (SIC)

Refers to the standard classification code for identifying the type of business conducted at a specific supply site.


Gas Shippers buy gas directly from producers or importers and contract with Gas Transporters to transport it through the Network.


The specific geographical location at which energy is supplied to, and later consumed by, an energy customer.

Small Site Peak Daily Demand

The Small Site Peak Daily Demand is calculated using the sum of consumption for all small sites.


Small and medium-size enterprise.


System Marginal Price (SMP) Buy is the highest price that gas was traded (buy or sell) by National Grid in its Network Code balancing role for delivery that gas day. An energy trading term.

SMP Sell

System Marginal Price Sell which is the lowest price that gas was traded (buy or sell) by National Grid in its Network Code for delivery that gas day.

Smart Meters

Smart meters provide customers and energy suppliers with accurate information on the amount of electricity and gas being used. Frequent capture of energy consumption data can be used to analyse energy performance, compare energy usage patterns and predict future business needs via an online management tool.


An organisation licensed to supply gas or electricity to consumers.

Supply Hourly Quantity (SHQ)

Supply Hourly Quantity refers to the maximum hourly consumption of a given supply point.

Supply Offtake Quantity (SOQ)

Supply Off-take Quantity (SOQ) equates to the maximum daily consumption of a given supply point.

Supply Point Address

This is the address at which the Supply Point is registered.

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A unit of energy measurement, often used alongside kWh. To calculate the equivalent value in kWh, multiply the number of therms by 29.3071.


A device used to adjust the voltage of an electric current. Transformers can be used to increase or decrease the voltage of an electrical power supply.


The transfer of a high-power electrical current from the UK’s power stations across the National Grid Company’s (NGC) nationwide grid system.

Transmission Use of System (TUoS)

These charges are incurred when transmitting electrical power across the National Grid network. The TUoS rate is calculated by applying a rate charge to the TRIAD demand level (see below).

Transportation Charge

The transportation charge is levied by the relevant Transporter and covers the cost of transporting gas through the relevant parts of the Gas Network. Transportation charges are calculated using three unique elements: capacity charge, commodity charge and site charge.


The National Grid uses Triads to calculate TUoS charges. A Triad is calculated by using the three maximum demand points of an electrical supply at half hourly intervals, before calculating the average total. Triad periods occur at peak times during the winter months, when the demand for electricity is at its highest.

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Unit Price

The price per unit of energy, calculated from three elements, including the wholesale energy price, infrastructure costs and the cost to serve.

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Watt (W)

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

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This is the agency owned by transporters to administer the processes that govern the gas supply chain. They operate systems that register each customer, with each meter and their supplier

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