UK utility glossary — the terms on your bill, contract and audit, explained.

The estimated annual gas consumption (or electricity equivalent on NHH) used to price contracts, allocate profile classes and calibrate settlement.

The Standard Licence Condition rule that limits how far back a supplier can charge for previously unbilled energy; typically 12 months for microbusiness and domestic supplies.

The charge that recovers the cost of balancing the national transmission system in real time; restructured in 2023 to be paid by generators only on the demand side.

The UK's mechanism for procuring guaranteed electricity capacity in advance, paid for through a levy on suppliers and ultimately on bills.

A voluntary scheme for energy-intensive sectors to receive reduced CCL in return for meeting agreed energy-efficiency targets.

A UK environmental tax applied to non-domestic energy supply, charged per unit of electricity, gas, LPG and solid fuel.

The licensed entities responsible for collecting half-hourly meter readings (DC) and processing them for industry settlement (DA).

The Distribution Code change that introduced excess-capacity penalties for half-hourly sites that exceed their agreed Available Capacity.

A default supply arrangement that takes effect when a non-domestic customer occupies premises without an active contract; typically priced well above tendered rates.

The deliberate reduction or shifting of electricity demand by customers in response to system or price signals; a revenue and cost-saving opportunity for flexible loads.

The charge electricity suppliers pay to regional Distribution Network Operators for using local distribution wires; recovered from customers through the unit rate.

A mandatory UK energy audit scheme for large undertakings, on a four-year cycle; Phase 4 compliance deadline is 5 December 2027.

The metering and settlement regime in which electricity consumption is measured and settled in 30-minute intervals; mandatory above 100 kW measured maximum demand.

The unit of reactive electrical energy; recorded on half-hourly meters and used to assess reactive-power and power-factor charges.

The unit of apparent electrical power; used to set Available Capacity on half-hourly electricity supplies.

The standard unit of electrical and gas energy on UK bills; one kilowatt of power sustained for one hour.

A signed authorisation that allows an intermediary to obtain a customer's utility data and tender on their behalf; does not authorise contract signature.

The Ofgem programme to extend half-hourly settlement to all UK electricity customers, leveraging smart-meter data; phased delivery through the late 2020s.

The licensed entity that owns, installs and maintains a half-hourly electricity meter; contracted separately from the energy supplier.

The 13-digit number that uniquely identifies a UK electricity supply point on the central industry database.

The 6-to-10-digit number that uniquely identifies a UK gas supply point on the central industry database.

An Ofgem-defined customer category with specific contractual and complaint protections; eligibility set by employee, financial or energy-use thresholds.

A long-term contract to buy electricity directly from a generator, often used by large UK customers seeking renewable supply with a defensible audit trail.

A free register held by suppliers and network operators that prioritises support for vulnerable customers during outages and emergencies.

The classification of UK non-half-hourly electricity supplies by typical demand pattern; used to estimate consumption between meter reads.

A certificate issued by Ofgem evidencing one MWh of renewable electricity generation; underpins UK green tariff claims.

A renewal contract that takes effect automatically at the end of an initial fixed term; subject to specific notification rules under Ofgem licence conditions.

A digital electricity or gas meter that records consumption in half-hourly intervals and communicates it to the supplier remotely.

Ofgem's overarching licence-condition obligation requiring suppliers to treat customers fairly across all stages of their interaction.

A mandatory UK disclosure regime requiring large companies and quoted groups to report energy and carbon data in their directors' report.

The unique identifier for a non-household water supply point in England, used by retailers and wholesalers since the 2017 market opening.

Ofgem's reform of how residual transmission and distribution network costs are recovered; replaced volumetric Triad and DUoS residual charges with fixed bands.

The voluntary industry code that sets standards for third-party intermediaries (energy consultants); a stepping-stone to the future statutory regime.

The charge for using the high-voltage national transmission grid, recovered from suppliers and ultimately from customers.

The three highest-demand half-hour periods on the GB transmission system each winter; historically determined large customers' transmission cost share. Largely superseded by the Targeted Charging Review.