Active power:

Also known as ‘Real Power’ or simply ‘Power’. Active power is the rate of producing, transfer or using electrical energy. Measured in watts and often-expressed in kW or MW.


An Amp is a unit that measures the rate of flow of an electrical current.

Apparent Power

The product of the voltage (volts) and the current amps. Comprises both active and reactive power. Measured in kVa or Mva.

Availability Charge:

The charge for the amount of power made available to the clients premises. It is related to the agreed supply capacity. The distribution company sets the rate and it is expressed in kVA.

Available Supply Capacity (ASC):

The agreed maximum supply capacity, measured in kVa, which a customer is allowed to take from the distribution system through their connection point. Customers pay a monthly charge for each unit of capacity. The maximum demand should not exceed the ASC.

Base Load:

The minimum amount of electricity being used during nonoperational hours.


Believing that market prices are about to fall.


The British Electricity Transmission and Trading Arrangement introduced in 2005 covering England, Wales and Scotland, replacing NETA which did not cover Scotland.

Bilateral Energy Trading:

Trading whereby two parties (for example a generator and a supplier) enter into a contract to deliver electricity at an agreed time in the future.


Believing that market prices are about to rise.

Calorific Value:

The ratio of energy to volume measured in mega joules per cubic meter (MJ/m).


These are used to add capacitance to the supply to eliminate the reactive element of the load.

Carbon Emissions Trading Scheme:

A scheme in which greenhouse gas emissions are controlled by setting a cap on total transmissions and allowing the market sectors to reach an economically balanced response via trading of emissions allowances. Allowances are allocated initially, perhaps through a free distribution or through an auction, and the total allocation is adjusted periodically.

CCGT (Combined Cycle Gas Turbine):

A gas fired electricity generation plant.

CCL Discount:

The benefits of the Climate Change Levy Discount Scheme result in up to 80% discount on the CCL in return for meeting energy or carbon saving targets.

CCL Relief:

A reduction of the CCL agreed as part of a trade sector Climate Change Agreement.

Climate Change Agreement:

An agreement between the Government and a business user, whereby a reduced rate of Climate Change Levy is payable in return for a commitment by the user to achieve certain predetermined targets for energy usage or carbon emissions. Climate

Change Levy (CCL):

A charge introduced by the Government on 1 April 2001 on UK non-domestic fuel. The Government’s aim when introducing the levy was to encourage business to use less energy, and contribute to the reduction of Carbon Dioxide emissions. Climate Change


Published in 2000, it sets out the government and Devolved Administration strategic approach to tackling Climate Change and meeting the UK’s Kyoto target of a 12% reduction in greenhouse gas emissions from 1990 levels by 2008-2012 and the domestic goal of reducing C02 emissions by 20% by 2010. CO2:

Carbon Dioxide – A Greenhouse gas. Cogeneration:

The simultaneous production of electricity and another form of useful energy (such as heat or steam) through the sequential use of energy, resulting in increased efficiency of fuel use. Combined

Heat and Power (CHP):

CHP is very efficient technology for generating electricity and heat together. A CHP plant is an installation where there is simultaneous generation of usable heat (normally for space heating) and power (usually electricity) in a single process. CHP typically achieves a 35-40% reduction in primary energy useage compared with power stations and heat only boilers.

Communication Charge:

The monthly fee payable by a customer, which covers the collection of half hourly data by the meter operator. This can be billed direct by the MOP or passed on through the current supplier.

Connection Agreement:

Agreement between client and the local distribution company (for example Central Networks in the Midlands) setting out the terms and conditions with which each are bound concerning the provision and use of the connection. Contract Price Structures: This indicates a supply offer, which has all delivery charges (DuoS & TuoS) built into the unit rates for the supply of electricity. Current


These are used to measure a load on a supply. They clamp round the cable and measure the EMF which is then converted into a current reading (A) Customers


Any structures, equipment, lines appliances or devices used or to be used by any customer and connected directly or indirectly to the Rec’s network. Data


The organisation appointed to aggregate the meter-reading data received from the appointed Data Collectors and forward it to suppliers.

Data Collector:

The organisation responsible for collecting, processing and validating the meter reading data, who then passes the information to the Data Aggregator.


The interruption of supply, so that electricity cannot flow from the network to the premises.


Department for Environment, Food and Rural Affairs. Demand Site


The planning, implementation, and monitoring of activities designed to encourage consumers to modify patterns of electricity usage, including the timing and level of electricity demand.


The requirement for power.


The permanent removal of the meter, cabling and service from the property once it is established that a supply will not be required in the future. This permanently removes the MPAN. Distribution


The local wires, transformers, substations and other equipment used to distribute and deliver energy to consumers.


Department of Productivity, Energy and Industry, formerly known as the Department of Trade and Industry. DUoS (Distribution Use of System): DUoS: