Glossary of Terms

AJAX progress indicator
Search: (clear)
  • a

  • AMR
    Automated Meter Reading - automatic collection of data from meters which is transferred to a central database for billing and/or analysis.
  • Annual offtake
    The expected or nominated annual consumption of gas at a supply point. Also referred to as AQ.
  • Annual Quantity
    Annual quantity. The sum of the annual consumption of all meters on a site. Measured in kWh or Therms.
  • AQ
    Annual quantity. The sum of the annual consumption of all meters on a site. Measured in kWh or Therms.
  • Automated Meter Reader
    Automated Meter Reading - automatic collection of data from meters which is transferred to a central database for billing and/or analysis.
  • Availability charge
    Electricity availability charges are based on an agreed level of required capacity and should be set at just above the anticipated maximum demand.
  • b

  • Balancing and settlement code
    Code governing the operation of the balancing mechanism and the imbalance settlement process and the relationships and responsibilities of all electricity market participants.
  • Balancing Mechanism
    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.
  • Baseload
    The load continuously supplied by generators into the electricity networks over a period of time that demand does not fall below.
  • Baseload Demand
    Minimum demand experienced by a generating plant.
  • c

  • Calorific Value
    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(...)
  • Capacitance
    The property of a capacitor that determines the quantity of electric energy that it can store.
  • Capacitor
    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.
  • Capacity
    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.
  • Carbon reduction Commitment
    An intensive energy users requirement to reduce carbon emissions measured in Tonnes.
  • CCA
    Climate change Agreement - a Gov't scheme in giving discounts to large energy users against their carbon emmisssion costs - CCL
  • 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.
  • CF
    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.
  • CHP
    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
    Climate change Agreement - a Gov't scheme in giving discounts to large energy users against their carbon emmisssion costs - CCL
  • Climate Change Levy
    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.
  • Combined Heat and Power
    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
    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.
  • Correction Factor
    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.
  • CRC
    An intensive energy users requirement to reduce carbon emissions measured in Tonnes.
  • Cubic Feet
    Unit of measure for volume of gas recorded by imperial meters.
  • Cubic Metres
    Unit of measure for volume of gas recorded by metric meters. One cubic metre = 35.31 cubic feet.
  • Curtilage
    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.
  • CV
    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(...)
  • d

  • DA
    The organisation appointed to aggregate electricity meter reading data received from data collectors to forward to suppliers.
  • Daily metered
    A gas supply point whose consumption is measured each day by means of a data logger.
  • Data aggregator
    The organisation appointed to aggregate electricity meter reading data received from data collectors to forward to suppliers.
  • Data collector
    The organisation responsible for collecting, processing and validating the meter reading data which is then passed on to the data aggregator.
  • Datalogger
    Device fitted to a meter that can record, store and transmit readings and measurements.
  • DC
    The organisation responsible for collecting, processing and validating the meter reading data which is then passed on to the data aggregator.
  • De Minimis
    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%).
  • Demand
    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.
  • Demand level
    The consumption of electricity in half-hourly intervals actually used on a national basis.
  • Demand-side Response
    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.
  • Distribution losses
    Charges relating to electrical losses that occur as electricity is transmitted through the lines of the DNO (see below).
  • Distribution network operator
    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).
  • Distribution use of system
    Charge levied by the DNO for the transmission of electricity through its local network.
  • DM
    A gas supply point whose consumption is measured each day by means of a data logger.
  • DNO
    One of 14 local distribution companies responsible for maintenance of the local distribution zone.
  • Domestic Site
    A site with an annual gas consumption of less than 73,200 kilowatt hours or 2,500 therms.
  • e

  • EHV
    Extra High Voltage.
  • Elexon
    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.
  • Emission allowance
    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(...)
  • Emissions cap
    The limit on emissions applicable to a participant over a period of time used to allocate emissions allowances.
  • Emissions credit
    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.
  • Emissions trading
    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.
  • Entry capacity
    The quantity of gas that a shipper is entitled to put into the system at a particular input point on a day.
  • EU-ETS
    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.
  • Exit capacity
    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.
  • Exit zone
    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
    Extra High Voltage.
  • f

  • Firm gas
    A guaranteed supply of natural gas that will not be subject to interruption.
  • Firm Supply
    A firm supply of gas is one that is guaranteed for a fixed period and will not be subject to an interruption or closure.
  • Forwards contract
    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.
  • Fossil fuel
    Coal, natural gas and fuels derived from petroleum.
  • Fundamentals
    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.
  • Futures contract
    Similar to a forwards contract these are normally traded through an exchange on standard contract terms with profits or losses calculated and paid daily.
  • g

  • Gas year
    Period commencing 06:00 1 October through to 06:00 1 October the following year.
  • Gate closure
    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.
  • Generator
    Producer of electricity.
  • Gigawatthour
    The equivalent to one thousand megawatts or one million kilowatts (kW).
  • Grid supply point
    Point between transmission and distribution systems where responsibility for electricity supply transfers from National Grid Transco to the local REC.
  • GWH
    The equivalent to one thousand megawatts or one million kilowatts (kW).
  • h

  • Half hourly data
    Half-Hourly data. Electricity consumption data recorded every half hour and collected by the metering system.
  • Half hourly metered
    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.
  • HHM
    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
    High Voltage. Supply voltage above 1000 volts (1kV).
  • HMC&E
    HM Customs & Excise.
  • HV
    High Voltage. Supply voltage above 1000 volts (1kV).
  • i

  • I&C
    Industrial and Commercial (non-domestic sector).
  • Imbalance
    Situation where there is a difference between the amount of power produced (supply) and the amount of power contracted or sold (demand).
  • Imbalance cost
    Cost to supplier of being in an imbalance situation.
  • Industrial & Commercial (I&C) site
    A site with an annual gas consumption of more than 73,200 kilowatt hours or 2,500 therms.
  • Interconnector
    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.
  • Interruptible gas
    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(...)
  • Interruptible Supply
    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(...)
  • k

  • Kilovoltampere
    Kilovoltampere. Unit of measurement for electricity available capacity and in some cases maximum demand. Referred to as KVArh when used to measure reactive power.
  • Kilowatt
    A unit of power, equal to 1,000 Watts. A watt is the standard power unit and a measurement of demand, including maximum demand.
  • Kilowatt Hour
    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(...)
  • kVa
    Kilovoltampere. Unit of measurement for electricity available capacity and in some cases maximum demand. Referred to as KVArh when used to measure reactive power.
  • kWh
    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(...)
  • Kyoto Protocol
    An international agreement signed in December 1997 that introduced emissions targets to be achieved by the period 2008 - 2012.
  • l

  • LEC
    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.
  • Levy exemption certificate
    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.
  • LF
    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.
  • Line loss factor
    Indicator within the electricity supply number of distribution line loss for a meter point.
  • Line pack
    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.
  • Liquified natural gas
    Oilfield or naturally occurring gas, chiefly methane, liquefied for transport or storage.
  • LLF
    Indicator within the electricity supply number of distribution line loss for a meter point.
  • LNG
    Oilfield or naturally occurring gas, chiefly methane, liquefied for transport or storage.
  • Load Factor
    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.
  • Local distribution zone (gas)
    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.
  • Local Distributor
    One of 14 local distribution companies responsible for maintenance of the local distribution zone.
  • Low Voltage
    Low Voltage. Electricity supply voltage below 1,000 volts.
  • LV
    Low Voltage. Electricity supply voltage below 1,000 volts.
  • m

  • Maximum annual quantity
    Annual quantity of gas multiplied by the MAQ percentage.
  • Maximum daily quantity
    Maximum aggregated daily quantity of gas to be delivered to a supply point.
  • Maximum demand
    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(...)
  • MD
    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(...)
  • Megawatt
    The equivalent to one thousand kilowatts.
  • Meter operator
    The organisation appointed to install and maintain metering equipment.
  • Meter operator agreement
    Agreement between the customer and the nominated meter operator.
  • Meter Point Administration Number
    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
    Meter Point Administration Service. Provides information regarding electricity supply to properties in their distribution network areas and regulates the registration process between electricity suppliers.
  • Meter point reference number
    Gas meter reference number.
  • MOP
    The organisation appointed to install and maintain metering equipment.
  • MPAN
    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.
  • MPAS
    Meter Point Administration Service. Provides information regarding electricity supply to properties in their distribution network areas and regulates the registration process between electricity suppliers.
  • MPRN
    Gas meter reference number.
  • MW
    The equivalent to one thousand kilowatts.
  • n

  • National Grid Transco
    Operates the high voltage national electricity transmission network and the gas transportation networks in England and Wales.
  • National offtake
    A gas metering point defining the boundary between the national transmission system and the Local Distribution Zone.
  • National transmission system
    The high-pressure network of pipes that transports gas between terminals, storage facilities and Local Distribution Zones for local distribution.
  • NDM
    Gas supply point whose meter is not fitted with a data logger and is read monthly, six monthly or at longer intervals.
  • Network
    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.
  • Network Code
    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.
  • Nominated Consumption
    The expected consumption of gas over a twelve month period used in a supply agreement.
  • Nominated interruption
    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.
  • Non-daily metered
    Gas supply point whose meter is not fitted with a data logger and is read monthly, six monthly or at longer intervals.
  • NTS (National Transmission System)
    The pipeline network and supporting facilities that are used to transport gas around the UK.
  • o

  • Objection
    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.
  • Offtake point
    Outlet of any control valve at any gas supply meter point.
  • Ofgem
    The Office of Gas and Electricity Markets. The industry regulator.
  • p

  • Percentage Day
    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.
  • PF
    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.
  • PGT
    A pipeline network operator, the largest of which used to be Transco, but is now National Grid.
  • Power Factor
    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.
  • PROC
    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.
  • Producer
    A company that explores for gas, drills the wells and extracts gas from the seabed.
  • Public Gas Transporter
    A pipeline network operator, the largest of which used to be Transco, but is now National Grid.
  • Public gas transporters
    Licensed gas pipeline operators.
  • Public registration system
    System for registering electricity supplies using Supply Numbers and MPANs.
  • r

  • Reactive power charge
    Charge for reactive energy if the average power factor falls below a preset level, normally 0.9.
  • Renewable energy
    Generation of electricity from infinite resources, e.g. wind power or hydro-electricity.
  • Renewable obligation certificates
    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.
  • Renewable sources of energy
    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.
  • Renewables obligation
    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.
  • RO
    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.
  • s

  • SBP
    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.
  • Settlement charge
    A flat fee to cover the collection of electricity data by the data collector.
  • Settlement period
    A half-hour period ending on the hour or half-hour.
  • Settlements Agency
    This is the body that "settles" the distribution of electricity to establish where and to whom the generated load has been distributed to.
  • Settlements charges
    A charge applicable to half-hourly metered supplies. Effectively a standing charge that covers balancing and settlement.
  • Shipper
    An organisation that contracts with National Grid Transco for the use of network code transportation and storage services.
  • Shipper nominated interruptible
    A gas supply that can be interrupted by its shipper to enable it to balance its supply and demand.
  • Site nomination
    Process by which a shipper informs National Grid Transco it wishes to supply gas to a new customer supply point.
  • Smart Metering
    Automated Meter Reading - automatic collection of data from meters which is transferred to a central database for billing and/or analysis.
  • Smart meters
    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.
  • Spill Surplus
    Electricity that a generator has produced but is not able to sell.
  • SSP
    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.
  • Standing charge
    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.
  • Supplementary number
    MPAN top line. Indicates the profile class and meter and time switch details.
  • Supply Point
    A group of one or more meters for which the PGT shall make natural gas available for offset by the Shipper.
  • System Buy Price
    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.
  • System Sell Price
    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.
  • t

  • Take or pay
    A contract whereby a customer must pay for a specific minimum quantity of gas irrespective of usage.
  • Tariff
    Published standard charges applied to gas and electricity supplies that are not on a bespoke negotiated contract.
  • Technicals
    Factors other than fundamental or psychological ones that influence future price developments e.g. trend indicators, moving averages, support and resistance levels etc.
  • Terrawatt
    Terawatt = 1,000GW.
  • Terrawatt hour
    Terrawatthour = 1,000 GWH.
  • Therms
    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.
  • Third party access
    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.
  • TNUoS
    Charges levied by the NGC for the transmission of electricity through the National Grid.
  • Transformer
    An electric device, without moving parts, for transferring electric energy from one or more circuits to one or more other circuits by electromagnetic induction.
  • Transmission
    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.
  • Transmission Losses
    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.
  • Transmission Use of Systems
    Charges levied by the NGC for the transmission of electricity through the National Grid.
  • Transportation
    Movement of gas from the beachhead terminal to Local Distribution Zones.
  • Transportation Agreement
    The agreement between an independent supplier of gas and the relevant PGT, for the movement of gas within the gas network.
  • Transportation charge
    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.
  • Triad
    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.
  • TW
    Terawatt = 1,000GW.
  • TWh
    Terrawatthour = 1,000 GWH.
  • u

  • UKDCS
    UK Data Collection Service. Former name of IM-Serv.
  • UKPX (UK Power exchange)
    A trading arena in which electricity can be bought or sold normally up to two days ahead of real time, often via the internet.
  • v

  • Voltage
    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(...)
  • w

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

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