Glossary of Terms

Automated Meter Reading - automatic collection of data from meters which is transferred to a central database for billing and/or analysis.

The expected or nominated annual consumption of gas at a supply point. Also referred to as AQ.

Annual quantity. The sum of the annual consumption of all meters on a site. Measured in kWh or Therms.

Annual quantity. The sum of the annual consumption of all meters on a site. Measured in kWh or Therms.

Automated Meter Reading - automatic collection of data from meters which is transferred to a central database for billing and/or analysis.

Electricity availability charges are based on an agreed level of required capacity and should be set at just above the anticipated maximum demand.

Code governing the operation of the balancing mechanism and the imbalance settlement process and the relationships and responsibilities of all electricity market participants.

The mechanism by which electricity demand is matched with electricity generation as near to real time as possible. It currently operates from three and a half hours ahead of delivery of the power up to the actual time of delivery.

The load continuously supplied by generators into the electricity networks over a period of time that demand does not fall below.

Minimum demand experienced by a generating plant.

This relates to the British Thermal Unit Correction Factor, which transfers the volume of gas to a measure of heat. This figure changes on a monthly basis, according to the ambient pressure and temperature of the gas within the system and is the multiplier by which cubic feet as a volume is(...)

The property of a capacitor that determines the quantity of electric energy that it can store.

A device consisting of two conducting surfaces separated by an insulator and having the ability of storing electric energy. Also called a condenser. Capacitors can be installed to control and improve the power factor.

Supply Capacity (or Availability) is a limit on monthly maximum demand agreed between the user and the regional distributor (normally via the supplier). Measured in kVA.

An intensive energy users requirement to reduce carbon emissions measured in Tonnes.

Climate change Agreement - a Gov't scheme in giving discounts to large energy users against their carbon emmisssion costs - CCL

A customs and excise levy charged to most commercial users of electricity since 2001. The levy is applied at a fixed rate per kilowatt hour.

Used by suppliers to calculate gas bills. The correction factor and the calorific value are the two variables used in the process of converting gas volume (as measured by the meter in cubic feet or cubic metres) into a measure of energy in kilowatt hours (kWh). Charges are based on kilowatt hours.

A power generation plant which produces electricity and uses the waste heat generated to warm a building or buildings. This may be small scale inside a factory or large scale where heat from a power station is used to provide heating for a local district containing domestic, commercial and(...)

Climate change Agreement - a Gov't scheme in giving discounts to large energy users against their carbon emmisssion costs - CCL

A customs and excise levy charged to most commercial users of electricity since 2001. The levy is applied at a fixed rate per kilowatt hour.

A power generation plant which produces electricity and uses the waste heat generated to warm a building or buildings. This may be small scale inside a factory or large scale where heat from a power station is used to provide heating for a local district containing domestic, commercial and(...)

Communication charges cover the cost of the telephone line or cellular link used for remote access to the electricity meter. This applies to half-hourly metered sites only. Communication charges can be billed to the customer by either the meter operator or the supplier.

Used by suppliers to calculate gas bills. The correction factor and the calorific value are the two variables used in the process of converting gas volume (as measured by the meter in cubic feet or cubic metres) into a measure of energy in kilowatt hours (kWh). Charges are based on kilowatt hours.

An intensive energy users requirement to reduce carbon emissions measured in Tonnes.

Unit of measure for volume of gas recorded by imperial meters.

Unit of measure for volume of gas recorded by metric meters. One cubic metre = 35.31 cubic feet.

The area of land within a boundary surrounding a property when not crossed by public highways, rail lines etc. Gas meter points sharing common ownership, purpose and curtilage may be aggregated to reduce transportation charges.

This relates to the British Thermal Unit Correction Factor, which transfers the volume of gas to a measure of heat. This figure changes on a monthly basis, according to the ambient pressure and temperature of the gas within the system and is the multiplier by which cubic feet as a volume is(...)

The organisation appointed to aggregate electricity meter reading data received from data collectors to forward to suppliers.

A gas supply point whose consumption is measured each day by means of a data logger.

The organisation appointed to aggregate electricity meter reading data received from data collectors to forward to suppliers.

The organisation responsible for collecting, processing and validating the meter reading data which is then passed on to the data aggregator.

Device fitted to a meter that can record, store and transmit readings and measurements.

The organisation responsible for collecting, processing and validating the meter reading data which is then passed on to the data aggregator.

If the amount of electricity supplied to a commercial site is less than 33 kWh per day and gas supplied less than 145 kWh per day respectively over a billing period then de minimis applies and VAT is charged at the reduced rate (currently 5%).

The rate at which electric energy is used in any instant or average over a period of time. Usually expressed in kilowatts (kW) or kilovolt-amperes (kVA). See also Maximum Demand.

The consumption of electricity in half-hourly intervals actually used on a national basis.

When large gas users turn down their gas usage in response to prices. See also interruptible supply. Distribution Network Operators (DNOs) DNOs are ex-Public Electricity Suppliers that came into existence on 1 October 2001. There are currently 14 Distribution Network Operators (DNOs) in the UK.

Charges relating to electrical losses that occur as electricity is transmitted through the lines of the DNO (see below).

Manages the installation and upkeep of their cabling and the distribution of electricity from the point where it leaves the transmission system to the supply point. They are also often referred to as the host Regional Electricity Company (REC).

Charge levied by the DNO for the transmission of electricity through its local network.

A gas supply point whose consumption is measured each day by means of a data logger.

One of 14 local distribution companies responsible for maintenance of the local distribution zone.

A site with an annual gas consumption of less than 73,200 kilowatt hours or 2,500 therms.

Extra High Voltage.

The balancing and settlement code company that procures and provides services to administer and implement the balancing and settlement rules. Signatories to the BSC contribute to the costs of Elexon. Charges are levied to recover the costs of running Elexon.

Typically, emissions reduction schemes set a cap for total emissions for each participant over a period and allocate each participant tradable units, called emissions allowances, up to the cap. Participants buy and sell emissions allowances and at the end of the period must hold allowances or(...)

The limit on emissions applicable to a participant over a period of time used to allocate emissions allowances.

Countries and companies can earn tradable emissions credits by undertaking projects that reduce emissions over and above what would occur in a business as usual scenario.

Countries and companies can trade emissions allowances and emissions credits. Emissions trading is one of the Kyoto mechanisms for reducing emissions of greenhouse gases contributing to climate change.

The quantity of gas that a shipper is entitled to put into the system at a particular input point on a day.

Countries and companies can trade emissions allowances and emissions credits. Emissions trading is one of the Kyoto mechanisms for reducing emissions of greenhouse gases contributing to climate change.

The quantity of gas that a shipper is entitled to withdraw from the national transmission system in order to meet the requirement of its customers on a day.

A geographical gas distribution area wholly contained within a local distribution zone which groups supply points together that, on a peak day, receive gas from the same national transmission system offtake point(s). Supply points in the same exit zone attract the same exit capacity charge rate.

Extra High Voltage.

A guaranteed supply of natural gas that will not be subject to interruption.

A firm supply of gas is one that is guaranteed for a fixed period and will not be subject to an interruption or closure.

An agreement to buy electricity from another party at a specified time in the future at a specified price with money changing hands at the delivery date.

Coal, natural gas and fuels derived from petroleum.

Factors other than psychological or technical that influence the price development on the physical or futures market, e.g. physical supply and demand, stock levels, currency exchange rates, interest rates, weather forecasts etc.

Similar to a forwards contract these are normally traded through an exchange on standard contract terms with profits or losses calculated and paid daily.

Period commencing 06:00 1 October through to 06:00 1 October the following year.

In relation to a settlement period, the time 3.5 hours before the start of that settlement period. It defines the moment when bilateral contracting ends and the Balancing Mechanism for each associated trading period begins.

Producer of electricity.

The equivalent to one thousand megawatts or one million kilowatts (kW).

Point between transmission and distribution systems where responsibility for electricity supply transfers from National Grid Transco to the local REC.

The equivalent to one thousand megawatts or one million kilowatts (kW).

Half-Hourly data. Electricity consumption data recorded every half hour and collected by the metering system.

Describes measurement of electricity consumption in half hourly intervals through a meter complying with the relevant Code of Practice (COP). COP3 for 1MW+ sites or COP5 for sites with demand over 100kW and up to 1MW.

Describes measurement of electricity consumption in half hourly intervals through a meter complying with the relevant Code of Practice (COP). COP3 for 1MW+ sites or COP5 for sites with demand over 100kW and up to 1MW.

High Voltage. Supply voltage above 1000 volts (1kV).

HM Customs & Excise.

High Voltage. Supply voltage above 1000 volts (1kV).

Industrial and Commercial (non-domestic sector).

Situation where there is a difference between the amount of power produced (supply) and the amount of power contracted or sold (demand).

Cost to supplier of being in an imbalance situation.

A site with an annual gas consumption of more than 73,200 kilowatt hours or 2,500 therms.

A cable connection allowing electricity to flow between two countries or markets. There are interconnectors between the north of England and Scotland and between the south of England and France.

Gas supply that may be interrupted by Transco or supplier to maintain the transmission/distribution system to allow supplies to firm gas consumers when there is a constraint on the system. Customers with an interruptible gas supply must have an alternative power supply should an interruption(...)

An interruptible supply is one whereby an agreement has been reached with the user that the service may be interrupted throughout the year, for a pre-determined nuAn interruptible supply is one whereby an agreement has been reached with the user that the service may be interrupted throughout(...)

Kilovoltampere. Unit of measurement for electricity available capacity and in some cases maximum demand. Referred to as KVArh when used to measure reactive power.

A unit of power, equal to 1,000 Watts. A watt is the standard power unit and a measurement of demand, including maximum demand.

A measure of electrical energy. One kilowatt hour (kWh) of energy is the energy produced by one kilowatt acting for one hour. Electricity and gas meters record in kilowatt hours and electrical and now gas consumption is billed in kilowatt hours.(kWh) Gas used to be billed in therms but that(...)

Kilovoltampere. Unit of measurement for electricity available capacity and in some cases maximum demand. Referred to as KVArh when used to measure reactive power.

A measure of electrical energy. One kilowatt hour (kWh) of energy is the energy produced by one kilowatt acting for one hour. Electricity and gas meters record in kilowatt hours and electrical and now gas consumption is billed in kilowatt hours.(kWh) Gas used to be billed in therms but that(...)

An international agreement signed in December 1997 that introduced emissions targets to be achieved by the period 2008 - 2012.

Exemption from the Climate Change Levy on the electricity to which the LEC relates. LECs are issued for electricity generated from renewable sources, good quality CHP and coalmine methane.

Exemption from the Climate Change Levy on the electricity to which the LEC relates. LECs are issued for electricity generated from renewable sources, good quality CHP and coalmine methane.

Ratio of average energy demand (load) to maximum demand (peak load) during a specific period. Usually stated as a percentage, or number of hours used.

Indicator within the electricity supply number of distribution line loss for a meter point.

Method used for providing short-term gas storage in which natural gas is compressed in transmission pipelines, providing additional amounts of gas to meet limited peak demands.

Oilfield or naturally occurring gas, chiefly methane, liquefied for transport or storage.

Indicator within the electricity supply number of distribution line loss for a meter point.

Oilfield or naturally occurring gas, chiefly methane, liquefied for transport or storage.

Ratio of average energy demand (load) to maximum demand (peak load) during a specific period. Usually stated as a percentage, or number of hours used.

A geographic area for which the total input and output demand for gas can be measured each day. LDZs are supplied by groups of offtakes from the national transmission system.

One of 14 local distribution companies responsible for maintenance of the local distribution zone.

Low Voltage. Electricity supply voltage below 1,000 volts.

Low Voltage. Electricity supply voltage below 1,000 volts.

Annual quantity of gas multiplied by the MAQ percentage.

Maximum aggregated daily quantity of gas to be delivered to a supply point.

The highest average electricity demand occurring in a half hour period. Maximum demand tariffs comprise of a) fixed monthly charge, b) an availability charge per kVA of the highest demand expected, c) a price per unit for day and night units, d) a maximum demand charge based on the measured(...)

The highest average electricity demand occurring in a half hour period. Maximum demand tariffs comprise of a) fixed monthly charge, b) an availability charge per kVA of the highest demand expected, c) a price per unit for day and night units, d) a maximum demand charge based on the measured(...)

The equivalent to one thousand kilowatts.

The organisation appointed to install and maintain metering equipment.

Agreement between the customer and the nominated meter operator.

Unique 21 digit number assigned to electricity meter(s) by MPAS under PRS (two tier number printed on electricity invoices preceded by an S. Top line referred to as Supplementary, bottom line as Core). Also known as Supply Number.

Meter Point Administration Service. Provides information regarding electricity supply to properties in their distribution network areas and regulates the registration process between electricity suppliers.

Gas meter reference number.

The organisation appointed to install and maintain metering equipment.

Unique 21 digit number assigned to electricity meter(s) by MPAS under PRS (two tier number printed on electricity invoices preceded by an S. Top line referred to as Supplementary, bottom line as Core). Also known as Supply Number.

Meter Point Administration Service. Provides information regarding electricity supply to properties in their distribution network areas and regulates the registration process between electricity suppliers.

Gas meter reference number.

The equivalent to one thousand kilowatts.

Operates the high voltage national electricity transmission network and the gas transportation networks in England and Wales.

A gas metering point defining the boundary between the national transmission system and the Local Distribution Zone.

The high-pressure network of pipes that transports gas between terminals, storage facilities and Local Distribution Zones for local distribution.

Gas supply point whose meter is not fitted with a data logger and is read monthly, six monthly or at longer intervals.

A distribution system in which the secondaries of the distribution transformers are connected to common conductors for supplying power directly to a customer's service.

A document that lays out the rights and responsibilities of all those using a Public Gas Transporter (PGT) network. The Network Code is normally used to refer specifically to the PGT network.

The expected consumption of gas over a twelve month period used in a supply agreement.

The designation by National Grid Transco of a gas supply point as being interruptible, allowing Transco the right to interrupt the gas supply for operational reasons.

Gas supply point whose meter is not fitted with a data logger and is read monthly, six monthly or at longer intervals.

The pipeline network and supporting facilities that are used to transport gas around the UK.

A notice issued to a shipper who received an involuntary withdrawal indicating that they wish to retain responsibility for the supply point. Offtake Gas consumed by a site or customer.

Outlet of any control valve at any gas supply meter point.

The Office of Gas and Electricity Markets. The industry regulator.

This refers to the percentage ratio of electricity used in the daytime against that used in the night. This information is used by suppliers to quickly identify the type of profile.

The ratio of active or real power in kilowatts (kW), to apparent power in kilovolt amperes or kVA. Power Factor is normally expressed as a figure between zero and one. Unity power factor is 100% (or 1.0) power factor which is the highest available. In practice 0.99 is the highest.

A pipeline network operator, the largest of which used to be Transco, but is now National Grid.

The ratio of active or real power in kilowatts (kW), to apparent power in kilovolt amperes or kVA. Power Factor is normally expressed as a figure between zero and one. Unity power factor is 100% (or 1.0) power factor which is the highest available. In practice 0.99 is the highest.

Tradable certificates issued by generators for each whole megawatt-hour of electricity generated from eligible renewable sources. ROCs can be converted into emissions allowances in the UK Greenhouse Gas Emissions Trading Scheme.

A company that explores for gas, drills the wells and extracts gas from the seabed.

A pipeline network operator, the largest of which used to be Transco, but is now National Grid.

Licensed gas pipeline operators.

System for registering electricity supplies using Supply Numbers and MPANs.

Charge for reactive energy if the average power factor falls below a preset level, normally 0.9.

Generation of electricity from infinite resources, e.g. wind power or hydro-electricity.

Tradable certificates issued by generators for each whole megawatt-hour of electricity generated from eligible renewable sources. ROCs can be converted into emissions allowances in the UK Greenhouse Gas Emissions Trading Scheme.

Energy sources that occur naturally and repeatedly in the environment, eg from the sun, the wind and the oceans, and from plants and the fall of water. It also refers to the energy available from wastes and to the emerging clean technology of fuel cells.

An obligation on electricity suppliers to source a specified percentage of the total electricity supplied to their customers in Great Britain is from eligible renewable sources. This must be evidenced by Renewable Obligation Certificates.

An obligation on electricity suppliers to source a specified percentage of the total electricity supplied to their customers in Great Britain is from eligible renewable sources. This must be evidenced by Renewable Obligation Certificates.

The price paid in the Balancing Mechanism by a party that requires more energy to meet its contractual commitments. Prices are often volatile and very high.

A flat fee to cover the collection of electricity data by the data collector.

A half-hour period ending on the hour or half-hour.

This is the body that "settles" the distribution of electricity to establish where and to whom the generated load has been distributed to.

A charge applicable to half-hourly metered supplies. Effectively a standing charge that covers balancing and settlement.

An organisation that contracts with National Grid Transco for the use of network code transportation and storage services.

A gas supply that can be interrupted by its shipper to enable it to balance its supply and demand.

Process by which a shipper informs National Grid Transco it wishes to supply gas to a new customer supply point.

Automated Meter Reading - automatic collection of data from meters which is transferred to a central database for billing and/or analysis.

Any meter which allows for the identification of consumption in more detail than a conventional meter. Smart meters will generally also include a means of communicating information to a central data collection site for energy management and/or billing purposes.

Electricity that a generator has produced but is not able to sell.

The price paid in the Balancing Mechanism by a party that has produced more electricity than it had users to buy. Prices are very volatile and often negative, meaning that a payment would need to be made to dispose of the unwanted electricity produced.

A charge designed to average over and recover from all customers on each tariff the elements of cost which are independent of consumption. Includes the costs associated with metering, billing and customer services.

MPAN top line. Indicates the profile class and meter and time switch details.

A group of one or more meters for which the PGT shall make natural gas available for offset by the Shipper.

The price paid in the Balancing Mechanism by a party that requires more energy to meet its contractual commitments. Prices are often volatile and very high.

The price paid in the Balancing Mechanism by a party that has produced more electricity than it had users to buy. Prices are very volatile and often negative, meaning that a payment would need to be made to dispose of the unwanted electricity produced.

A contract whereby a customer must pay for a specific minimum quantity of gas irrespective of usage.

Published standard charges applied to gas and electricity supplies that are not on a bespoke negotiated contract.

Factors other than fundamental or psychological ones that influence future price developments e.g. trend indicators, moving averages, support and resistance levels etc.

Terawatt = 1,000GW.

Terrawatthour = 1,000 GWH.

A therm is an imperial measure of heat energy equivalent to 29.3071 kilowatt hours. Therms have been largely replaced by kilowatt hours as the standard unit of measure on gas bills and supply agreements.

Right of any gas or electricity supplier to have access to the national transmission system of that energy even though the system is operated and/or owned by another organisation.

Charges levied by the NGC for the transmission of electricity through the National Grid.

An electric device, without moving parts, for transferring electric energy from one or more circuits to one or more other circuits by electromagnetic induction.

The transfer of electricity at high voltage from power stations across the UK through wires on pylons to points where it can be distributed to users.

In transmitting electricity from generator to local REC area, some electricity is lost. Specific calculations have to be made by suppliers to determine the level of these losses.

Charges levied by the NGC for the transmission of electricity through the National Grid.

Movement of gas from the beachhead terminal to Local Distribution Zones.

The agreement between an independent supplier of gas and the relevant PGT, for the movement of gas within the gas network.

The charges associated with transporting gas from the beach to Local Distribution Zones. Prices are based on a distance related tariff system and vary depending on interruptible and firm supply.

The National Grid takes readings of maximum demands three times a year. The average of the three readings is used by the National Grid to calculate the transmission charges.

Terawatt = 1,000GW.

Terrawatthour = 1,000 GWH.

UK Data Collection Service. Former name of IM-Serv.

A trading arena in which electricity can be bought or sold normally up to two days ahead of real time, often via the internet.

The force that causes a current to move through some resistance, in this case, the National Grid. In industry terms, electricity moves round the main grid at a high voltage. When it is stepped down to the level of a smaller grid or an actual site it is regarded as low voltage. Low voltage(...)

Price paid on the open markets for energy only i.e. excluding transportation and distribution charges, supplier margins etc.

The company that maintains the gas sites and meters database and holds the key supply point data used throughout the industry.