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The language and terms used within the energy industry can sometimes be confusing. Therefore the Utility Centre have compiled a list of terms and there definitions to help avoid confusion.

  • Advanced Meter

Meters that automatically pass accurate meter readings to energy suppliers

  • Amp

An amp is electrical current

  • Annualised Advance

The actual rate of consumption over a period between two actual meter readings 

  • AQ (Annual Quantity)

The term used to describe the annual consumption of a gas customer’s meter

  • Apparent Power

Apparent power is equal to the product of volts and amps

  • Applying supplier

The future supplier of a meter, also known as the incoming supplier or new supplier when subject to a transfer

  • Available Supply Capacity (ASC)

The maximum amount of electricity that can be drawn via the meter at any point. Measured in KVA

  • Balancing and Settlement Code (BSC)

The rules that govern the settlement and metering systems in the electricity market. Managed by ELEXON

  • Big 6

The major energy suppliers in the UK: BGB, SSE, nPower, E.ON, Scottish Power and EDF

  • Buy-Out Fund

Where a supplier is unable to meet the RO they must make payments into a fund for renewable investment

  • Calorific Value (CV)

The quality of gas measured by the release of energy when gas is completely combusted under specified conditions

  • Capacity

As ASC, the maximum amount of electricity that can be drawn via the meter at any point. Measured in KVA

  • Change of tenancy

The situation where a business energy customer moves in to a premise without a contract being in place

  • Climate Change Levy (CCL)

Introduced in 2001 and levied on businesses to incentivize the use of renewable to increase efficiency and reduce carbon emissions

  • Communications Service Providers (CSP)

The telecommunications businesses, Arqiva  & Telefónica who will facilitate the full functionality of smart metering

  • Consumption

The absolute usage of a meter, derived from the meter advance and applicable to any time period, most often annual 

  • Contract End Date

The end of a fixed price period, the supplier will supply past this date until the supply end date

  • Contracts for Differences (CfDs)

Replacement for RO, mechanism for top-up payments to renewable plants when electricity price is below a set level

  • Correction Factor

The measure used to convert cubic meter gas units into kWh, the standard correction factor is 1.02264

  • Credit Score

A snap shot indicator of a business’ credit worthiness used to determine the products, rates and terms suppliers will offer 

  • D0010 – Meter Readings

The flow that communicates Meter Readings taken from a customer meter to the industry

  • D0019 – Metering System EAC/AA Data

Derived from the D0010, the flow communicates the estimated annual consumption of a meter

  • D0036 – Validated Half Hourly Advances for Inclusion in Aggregated Supplier Matrix

The flow that contains the meter readings, demand and advances of a Half Hourly Meter

  • D0055 – Registration of Supplier to Specified Metering Point

Registers the supplier’s intent to register a meter to their portfolio

  • D0057 – Rejection of Registration

Reports a rejection of the D0055 because certain critical industry data does match that held by MPAS

  • D0058 – Notification of Termination of Supply Registration

Informs the incumbent supplier that the new supplier is intending to take ownership of the meter on the date stated

  • D0064 – Notification of an Objection to Change of Supplier Made By the Old Supplier

Notification that the incumbent supplier is ‘objecting’ to the transfer of the meter point to the new supplier

  • D0067 – Notification of an Objection to Change of Supplier Sent to the New Supplier

Sent to the new supplier to inform them that the incumbent supplier has objected to the transfer of the meter

  • Data Aggregator (DA)

The entity that sums the meter readings gathered in order to identify the demand levels in any combination of meters

  • Data Collector (DC)

The entity that collates the meter readings and attributes them to metering systems, customers and suppliers

  • Data and Communications Company (DCC)

The entity responsible for linking the 53 million smart meters with the systems of the energy suppliers and network operators

  • Data Flow

Flows transmitted between the MOP, DC, DA, MPAS, Supplier and Distributor via the DTN facilitating actions in the competitive market

  • Data Retriever (DR)

The ‘man in the van’ who reads meters; in a Smart Meter this can simply be a SIM card

  • Data Service Provider (DSP)

The entity that operates the system controlling the movement of smart meter messages, a smart meter era DR and DC

  • Data Transfer Catalogue (DTC)

The dictionary of the various flows, activities and participants within the DTN

  • Data Transfer Network (DTN)

The data network that enables automated communications between the relevant market participants facilitating change of supplier activity

  • DECC (Department of Energy & Climate Change)

The government department responsible for the energy industry & which controls Ofgem

  • Deemed rates

Standard charges applied to Change of Tenancy customers before they agree or refuse a contract with the incumbent supplier

  • Delphi

The numeric score provided by Experian to represent a business’ credit worthiness

  • Distribution Network (Distributor)

The 14 ‘regional’ networks that connect to the transmission system and manage electricity distribution to homes and businesses

  • DUoS (Distribution Use of System)

The charges related to a meter’s usage of the distribution network representing around 18% of the average business energy bill

  • Economy 7 Meter

A two-rate meter to provide cheaper energy off-peak between 1am and 8am and commonplace in bakeries and take-aways


The party that manages the BSC focusing on settlement processes, metering systems & managing supplier adherence to industry rules

  • Embedded generation

Small scale generation, often renewable, that is in place at a site of an energy consumer and not a generator

  • Energy Ombudsman

Part of the Ombudsman Service covering  the communications, energy, property and copyright licensing industries to whom escalated complaints are made

  • Energy Supplier

The entity that is the retail business who bills and services end user customers e.g. BGB, nPower, E.ON

  • EAC (Estimated Annual Consumption)

The term used to describe the forecast annual consumption of a electricity customer’s meter in lieu of an Annualised Advance

  • Evening Weekend Meter

A two-rate meter measuring day & evening / weekend usage. Commonplace in bakeries and take-aways

  • Evening Weekend & Night Meter

A three-rate meter measuring day evening / weekend & night usage. Commonplace in pubs, nightclubs and restaurants

  • Feed in Tariff (FIT)

A scheme to incentivise renewable energy generation. Levied on all consumers to reward those businesses with eligible generation

  • Fossil Fuel Levy (FFL)

A forerunner of Climate Change Levy, introduced in 1989 and which has been rated at 0 since 2002


The private business contracted to operate the MRA as MRASCO and the SEC

  • Generators

The producer of electricity using coal, gas, hydro, oil, wind or waves but whose fundamental principle remains the same

  • GWH (Giga Watt Hour)

1,000,000 kWh, 1,000 MWH

  • Global Complex

The connected nature of the globalised energy market whereby e.g. demand in Japan can affect supply and price in the UK

  • Grid

The network that transports energy from source to destination. Also describes the payment market between suppliers & generators

  • GSP (Grid Supply Point)

The point in each regional distribution network where the transmission network connects to it

  • Half Hourly Data (HHD)

Data sourced from a half hourly meter delivering 17,520 recordings of demand from each meter

  • Half Hourly Meter (HH Meter)

A high demand meter (>100kW) that records and transmits usage every half hour

  • Higher Distribution Cost Levy (Assistance for Areas with High Electricity Distribution Costs)

A charge to reduce the cost of the distribution of electricity in certain areas such as the North of Scotland.

  • Incumbent supplier

The current supplier of a meter, also known as the outgoing or old supplier when subject to a transfer

  • Industrial & Commercial

Those customers that consume more than 300,000kWh of gas or electricity per annum and often those electricity customers fitted with a half hourly meter.

  • Interruptible Supply

Specialised contracts for intensive gas users to cut demand in peak periods to balance the network 

  • kVA (Kilo volt amperes)

A measure of the difference between real and apparent power arising because of inefficiencies in electrical transmission

  • kW (Kilowatt)

A measure of power output or demand of a particular item, it is equal to one thousand watts

  • kWh (Kilowatt hour)

A measure of power taken over time; 1,000 watt-hours or 3.5 mega joules

  • Levy Exempt Power

Electricity from a non-fossil fuel source of generation e.g. renewable energy and therefore not liable for CCL

  • Line Loss Factor (LLF)

A multiplier applied to a meter & used to estimate the losses in transporting energy along the distribution network

  • Liquidity

Availability of commodity in a traded market, the higher, the stronger liquidity and lower the influence of a single transaction

  • LNG (Liquid Natural Gas)

Gas converted & compacted to less than 1/600th of its gaseous state to facilitate ease of transportation over long distances

  • Load Factor

The absolute consumption divided by the maximum energy ‘demanded’ at a specific point as measured by a Maximum demand meter 

  • Load Profile

The pattern of a meter’s electricity usage by period to a half hour granularity. Eight profile classes represent standard profiles 

  • Losses

Energy is lost during transportation, metered demand is therefore subject to a loss factor to gross up demand to include losses 

  • Maximum Demand (MD)

The maximum energy ‘demanded’ by a metering system at a specific point

  • Maximum Demand Meter (MD Meter)

A meter that measures the maximum energy ‘demanded’ at specific points & the absolute consumption to provide the load factor

  • Measurement Class

The aggregation & settlement classification for a meter i.e. Non Half Hourly or Half Hourly

  • MWH (Mega Watt Hour)

1,000 kWh 

  • Meter advance

The gap between two meter readings derived by subtracting the earlier read from the later 

  • Meter Asset Manager (MAM)

The entity who maintain the meter installed in a premise 

  • Meter Asset Provider (MAP)

The entity who owns the meter installed in a premise 

  • Meter Operator (MOP)

The collective name for the MAM and MAP, the owner and maintainer of a the meter installed in a premise 

  • Meter Serial Number

The non-unique serial number of a gas or electricity meter, used to identify the meter and not the supply point 

  • Meter Timeswitch Code (MTC)

Identifies the rate/time periods that a meter will support to measure meter consumption across differing periods

  • Micro Business

A business using under 100,000kWh of electricity, 293,000kWh of gas, with fewer than 10 staff and turnover less than €2m

  • Micro Watt Hour

1,000,000th of a kWh 

  • Milli Watt Hour

1,000th of a kWh

  • M Number (MPRN, Meter Point Reference Number)

The unique reference applied to the gas supply point in a premise, the gas industry version of the S Number 

  • MPAN Core

The unique reference for a metering system at a supply point. The ‘bottom line’ of the S Number 

  • MPAS

The 14 regional areas that hold centralised data about each customer meter and supply point 

  • MRA (Meter Registration Agreement)

The rules that govern the DTN and underpin the registration processes of the electricity market. Managed by MRASCO.


The organisation that is contracted to develop and manage the MRA. Operated by GEMSERV. 

  • National Grid

The Company that owns the electricity transmission network and the gas pipeline network 

  • Network Code (The Uniform Network Code)

The legal framework of the gas industry designed to facilitate competition. 

  • Objection

The process within the registration window where the supplier blocks the transfer due to debt or contracts being in place 

  • Ofgem

The non-customer facing industry regulator responsible for the competitive energy market, a non-ministerial government department reporting to DECC 

  • Out of Contract rates

Punitive rates charged to customers who have refused contract terms yet remain on supply with the supplier. 

  • Pass Through Charges

Elements of the energy price that can be changed and passed through under the contract terms e.g. levies, transportation & metering costs. 

  • PWH (Peta Watt Hour)

1,000,000,000,000 kWh, 1,000,000,000 MWH, 1,000,000 GWH, 1,000 TWH. 

  • PP10

HMRC’s Climate Change Levy Relief Supporting Analysis document intended to prove, via supporting analysis, a business’ claim for relief. 

  • PP11

HMRC’s document to inform an energy supplier of the level of relief to be applied against a business’ CCL liability.

  • Producer

The entity who extracts gas through on and offshore wells and deliver it to the market. 

  • Profile Class

A classification representing one of 8 generic demand shapes approximating when a typical customer uses their energy.

  • Profile Class 1

A standardised load profile for domestic unrestricted customers using a single rate meter

  • Profile Class 2

A standardised load profile for domestic unrestricted customers using an economy 7 two-rate meter

  • Profile Class 3

A standardised load profile for non-domestic unrestricted customers using a single rate meter

  • Profile Class 4

A standardised load profile for non-domestic unrestricted customers using an economy 7 two-rate meter

  • Profile Class 5

A standardised load profile for non-domestic Maximum Demand (MD) with a Peak Load Factor (LF) of less than 20%

  • Profile Class 6

A standardised load profile for non-domestic Maximum Demand (MD) with a Peak Load Factor (LF) of between 20% and 30%

  • Profile Class 7

A standardised load profile for non-domestic Maximum Demand (MD) with a Peak Load Factor (LF) of between 30% and 40%

  • Profile Class 8

A standardised load profile for non-domestic Maximum Demand (MD) with a Peak Load Factor (LF) of over 40%

  • Reactive Power

Created when current and voltage are not in phase, measured in var and also known as apparent power 

  • Real Power

Real power is the amount of actual power that can be drawn from a circuit. 

  • RECs (Regional Electricity Companies)

The pre-privatisation era description of monopoly regional energy businesses e.g. MEB, now nPower or EMEB, now E.ON

  • Registration

The process by which a customer is transferred from their existing supplier to their chosen new supplier 

  • Registration Window

The 28-day period prior to the intended transfer date within which the new supplier applies for registration of the meter. 

  • Regulator

Ofgem, the non-customer facing industry regulator responsible for the competitive energy market, a non-ministerial government department reporting to DECC 

  • Rejection

The process within the registration window where MPAS rejects the application due to mis-matching industry data 

  • Renewables Obligation (RO)

An obligation placed on UK electricity suppliers to source a set % of their energy from renewable sources. 

  • Renewable Obligation Certificates (ROCs)

Certificates of provenance, under the RO presented to Ofgem to prove the source and status of the energy.

  • Retail Price

The final price for energy that the customer pays. Consisting of wholesale energy, transportation, metering, losses, levies, & supplier margin.

  • Seasonal Time of Day Meter (STOD)

A complex meter with up to 56 rates across night, day, peak & other periods measured separately by season. 

  • Settlement

The process, in the electricity market, total and individual demand is apportioned to each supplier, customer & GSP group 

  • Settlement Period

Each half hour in the electricity market is a settlement period within which total and individual demand is apportioned 

  • Settlement Register

A register on a meter related to a time period & used in the industry settlement process to determine usage

  • Shipper

The entity that arranges for the gas transporter to move the gas from the producer to the customer.

  • Smart Energy Code (SEC)

The multiparty agreement that sets out the contractual relationship between the DCC and the DCC Service Users. Operated by GEMSERV.

  • Smart Meter

Meters that automatically pass accurate meter readings to energy suppliers and which support other functions including enabling smart appliance operation.

  • Smart Meter Roll-Out

The government project to install 53 million Smart & Advanced Meters between 2015 and 2020

  • SME (Small & Medium Enterprise)

Independently owned businesses Small: below £2.8m turnover & 50 employees Medium: below £11.2 million turnover & 250 employees

  • S Number

A unique identifier used in the electricity market to define the supply point for a meter and its generic characteristics.

  • Soft Credit Check

A credit check that leaves no footprint on financial records yet determines the products, rates and terms suppliers will offer

  • Spill

Embedded generators releasing surplus energy to the ‘grid’ to take advantage of price opportunities as a traditional generator would

  • Standard Meter

A single rate meter, providing a single tariff for all units used. Ideal for offices, shops & cafes.

  • Storage

Primarily gas however small amounts of electricity can be stored, with new technologies exploring long-term mass electricity storage. 

  • Supply End Date

The final date a supplier supplies a meter, after which they no longer hold responsibility for the energy delivered. 

  • TWH (Tera Watt Hour)

1,000,000,000 kWh, 1,000,000 MWH, 1,000 GWH 

  • Therm

The historic measure of gas consumption, equal to 100,000 BTU (British Thermal Units) and 29.3 kWh 

  • TPI (Third Party Intermediary)

A broker, consultant, agent or price comparison website, i.e. any non-supplier party involved in the business energy sales process. 

  • TNUoS (Transmission Use of System)

Charges for a meter’s usage of the transmission network, varying by length & location representing 7% of the energy bill 

  • Top Line

The first 8 digits of the S Number displaying Profile Class, Meter Timeswitch Code and Line Loss Factor. 

  • Transco

Part of National Grid, the company that owns the gas pipeline network of the UK 

  • Transmission Network

The wires and pylons that carry electricity from generators to the distribution networks. Owned and managed by National Grid 

  • Transportation

The charges for and process by which gas and electricity is delivered from the generator to the meter point.

  • Transporter

The entity, primarily National Grid Transco, that transports gas from the producer to consumers. 

  • Triad

The three highest demand points between November and February, used to determine transmission charges applied to the largest businesses.

  • Vertical integration (VI)

The principle of a business owning more than one area of the energy chain: generation, transportation, metering and/or supply.

  • Volt

A volt is electrical pressure.

  • Watt

A watt is real power.

  • Wholesale Market

The energy market where suppliers, generators, traders and customers purchase electricity and gas via bilateral contracts or through energy exchanges.