Energy terms explained

The amount that a customer would have to pay for gas, electricity or both over one whole year.

A written document that suppliers must provide to each customer, each year. The Annual Statement contains a range of key tariff information, including tariff name, consumption over the previous 12 months and estimate of annual cost for the next 12 months.

Describes the interest rate for a whole year, rather than just a monthly fee or rate, as applied on a loan, mortgage, credit card etc. It is a finance charge expressed as an annual rate.

The Gas and Electricity Markets Authority, sometimes referred to as GEMA, that acts as our governing body.

Where, due to the terms of a contract, a supplier has the ability to extend the duration of an existing Fixed Term tariff or apply a new Fixed Term tariff without a consumer’s positive assent.

A back-bill is a ‘catch-up’ bill sent to you by your gas or electricity supplier when you haven’t been correctly charged for your energy use. Back-bills can be for any amount but there is a principle in place defining when and for how far back your supplier can charge you.

For more information see our Back-billing leaflet.

A factor that may limit a firm’s ability to enter the market.

A factor that may limit a firm’s ability to increase in size.

Any form of payment, saving, rebate benefit or reward that is in any way linked to a Domestic Energy Supply Product, and which involves the provision of any goods or services which do not relate to energy supply. One example is a supermarket voucher.

An opt in bundle for the purpose of this proposal is when consumers can add on additional services/products to their energy offering.

A tied bundle for the purpose of this proposal is a form of pure bundling where it is tied/mandatory to buy the entire bundle to receive all the products and services offered, ie the specific energy offering is only available with this particular bundled form.

An opt out bundle for the purpose of this proposal is a when a consumer is presented with an entire bundled product and they are required to opt out of the additional services if they wish to only purchase the energy element of the bundle or if they wish to opt out of any one of the elements of the bundled product.

A tariff which guarantees that the price per kWh for gas/electricity will not rise beyond a certain level for a fixed period.

The presentation of unit rate, or a fixed monthly/daily amount that you pay your electricity/gas supplier for maintenance and other costs, such as maintaining connection to the power network.

The Clean Heat Grant scheme (CHG) is a proposed government grant scheme designed to help increase deployment of low-carbon heating technologies. Targeted at households and small non-domestic buildings, the scheme will offer upfront capital grants to enable the installation of heat pumps and, in limited circumstances, biomass boilers.

A set of guidelines and principles to be followed by members of some profession, trade, or group. In this case, energy suppliers.

Offshore transmission licences are granted to companies to operate the pipes, cables and other assets that transport energy generated offshore to Britain's mainland.

Licences are granted through a competitive tender process which we manage. In doing so, we make sure that generators are partnered with the most efficient and competitive players in the market. This should result in lower costs and higher standards of service for power generators and, ultimately, consumers.

Usually refers to a period of time after the consumer has entered into a contract or signed up to a tariff during which they can reverse their decision without incurring any cancellation fees.

The charges for supply of electricity/gas combined with all other terms and conditions that apply, or are in any way linked, to a particular type of contract for the supply of gas/electricity to a domestic customer excluding certain matters such as dual fuel discounts, variations in charges relating to payment method, appropriate surcharges and optional additional services or products.

The part financing of one product or activity by another.

A tariff in respect of an evergreen contract which is no longer capable of being entered into by all domestic customers.

This normally applies if you move into a new business premises and don’t agree a contract. You could also be on one if your current contract ends but the supplier continues supplying energy that you use. This might happen if the original contract does not state what will happen at the end of a contract or it does not have renewal provisions.

Deemed contracts and default tariffs are usually among a supplier’s most expensive. They are your supplier's most basic offer.

These are the basic tariff an energy supplier offers. 

You could be put on a default deal if:

• you've not chosen an energy tariff (for example if you've moved into a property and not agreed a new tariff)
• a fixed-term tariff you've chosen ends and you've not asked to switch to a new one you've selected.
• your supplier exits the energy market and Ofgem appoints a new supplier to take on your energy supply. The new supplier we appoint will usually put you on their default deal until you ask to change it or switch away.

The most common type of default tariff is a 'deemed tariff' that is ‘standard variable’. Standard variable means the prices you are charged for the energy you use will go up and down with the costs to buy energy in the market. These tariffs don’t generally have an end date and won’t have a fixed-term on the contract terms and conditions, such as for your gas or electricity unit prices. 

Names of default tariffs vary. If you aren’t sure if you are on one, the supplier for your property can tell you or check a last energy bill.

An exemption from or relaxation of a rule (which may include the imposition of alternative rules).

Switching Programme Design Authority

The Design Authority (DA) owned the design baseline for the Switching Programme and made decisions on the design of the new switching arrangements that, in total, formulated the design baseline. The DA consisted of senior representatives in Ofgem from all of the policy areas affected by the Switching Programme.

A determination is a binding decision by us, including our reasons, in relation to a dispute referred to us under the Acts or the relevant licence provisions.

The circumstances in which a dispute between a licensed energy network company and a customer may be referred to the Gas and Electricity Markets Authority (“the Authority”) for determination are set out in: Ofgem guidance on determination of disputes. 

Individual determinations are published on our Electronic Public Register.

A method of payment where a fixed or variable amount is taken from a bank account each month, quarter or year.

Any form of payment, saving, rebate benefit or reward that is in any way linked to a Domestic Energy Supply Product. One example is the dual fuel discount.

A customer that uses energy for non - commercial purposes.

Companies who sell energy to and bill domestic customers in Great Britain.

A type of energy contract where a customer takes gas and electricity from the same supplier (or two affiliated suppliers).

This is where you take both your gas and your electricity from the same supplier. A supplier may offer a discount off your bill if you buy both your gas and your electricity from them.

A particular type of electricity meter where the tariffs have a control unit that allows the supplier (or distribution company) to switch the metered supply remotely by radio teleswitch. The RadioTeleswitching Access Provider controls the radio switches, and therefore heating load, following instructions from the supplier.

Where the average costs of producing a good or providing a service falls as output increases.

A type of tariff that has different unit rates for consumption during the day and during the night. The number following Economy refers to the number of hours for which night-time rates are available.

A communication from a supplier to a consumer, indicating that the fixed term period of the consumer’s energy supply contract is due to expire, and setting out the arrangements that the consumer will default to and the options available to the consumer to act in response to this notification.

The use of gas and/or electricity as a source of heat and power. Usage is measured by an energy meter.

The device used to record how much gas and/or electricity is used.

An energy company licensed by Ofgem to supply gas and/or electricity.

This is the company your pay for your energy usage. They buy energy in the wholesale market and sell it on to customers. You can shop around and choose who your energy supplier is.

When we talk about or publish data on energy suppliers, we sometimes classify them by their share of customers in the retail market:

• Small suppliers: hold less than 1% of the market in both fuels (gas and electricity)
• Medium suppliers: hold less than 5% of the market in both fuels (gas and electricity) and 1% or more in a single fuel (gas or electricity)
• Large suppliers: hold 5% or less of the market in at least one fuel (gas or electricity)
• Large legacy suppliers: have held at least 5% of the market in either fuel since the government transferred the ownership of gas and electricity from public to private ownership in the 1980s.

Tariffs are what energy suppliers charge you for gas and electricity. If you don't know what your energy tariff is, contact your energy supplier or check your last energy bill. 

You can find your supplier's contact details on your gas or electricity bill. If you don’t know who your supplier is see Who is my gas or electricity supplier?

You should talk to your supplier or look at their website to see what tariffs they have available and if you can pay less. You can also use a price comparison website to see if another supplier can offer you a better tariff. A list of Ofgem approved online comparison services are available at Ofgem Confidence Code.

If you’ve never switched energy supplier or have switched only once, you’re likely to be on a more expensive ‘default’ tariff. Default tariffs, including standard variable tariffs, are a basic tariff from an energy supplier. Find out about the default tariff price cap

A prepayment meter tariff means you pay upfront for your gas or electricity use. You can ‘top up’ using an app on your phone, by text or through a token or key card at a shop. Find out about the prepayment tariff price cap

These are the costs of government programmes to save energy, reduce emissions and encourage take up of renewable energy. They also include the cost of social programmes like the Warm Homes Discount.

Find out more about these at Environmental and social schemes

When an energy supplier tries to take over a gas or electricity supply by mistake. As a customer, you’re protected by the ‘Erroneous Transfer Customer Charter’. This is outlined in the electricity Meter Registration Agreement and gas Supply Point Administration Agreement industry codes. All energy suppliers must follow the charter. You could get compensation if this happens to you.

Estimate of the amount of energy used in a particular period of time, for example over the last three months.

The estimated cost of energy to a consumer over a 12 month period, based on a specified methodology and the best available information about that consumer’s consumption.

A tariff which is for a period of an indefinite length and which does not contain a fixed term period.

A tariff with specific terms applying to the contract conditions. Usually these lock-in a price for a fixed period, amongst other services.

A tariff where the price per kWh for gas/electricity will not change for a set period of time.

A tariff with a fixed end date.

The pipe carrying the hot water flow leaving an installation.

Those households who need to spend more than 10 per cent of their annual income on fuel to maintain an adequately heated home are considered to be in fuel poverty.

Fir more information visit the main Great Britain Security and Quality of Supply Standard (GB SQSS) page.

A scheme that allows householders to improve the energy efficiency of their homes and repay the cost through energy bills.

Full information can be found on Green Deal: energy saving for your home. 

The Green Gas Support Scheme (GGSS) is a government environmental scheme that provides financial incentives for new anaerobic digestion biomethane plants to increase the proportion of green gas in the gas grid.The scheme is open to applicants in England, Scotland and Wales for four years from 30 November 2021.

Registered participants will receive quarterly payments over a period of 15 years. Payments are based on the amount of eligible biomethane that a participant injects into the gas grid. For more information please see the webpage for the Green Gas Support Scheme. 

A tariff that is promoted primarily on the basis of its association with renewable energy sources and/or climate change mitigation.

This allows suppliers to offer competitive deals underneath the set level of a price cap. It is calculated as a proportion of other cost elements.

A consumer who annually uses 5.100 kWh of electricity and/or 23.000 kWh of gas.

We calculate network costs using the Ofgem Supply Market Indicator (SMI). This is our 12-month forward look at the pricing trends and costs which make up an average energy bill. The network costs represented in the SMI do not take account of the costs that generators are charged for using the gas and electricity networks.This portion forms a small part of electricity wholesale costs.

We estimate the domestic charges received by suppliers from network companies and assume that these charges are directly passed on to customers through bills. However, in practice, suppliers may choose to allocate these costs across their customer base in a different way. You can find out more on our SMI page.

The balancing charge (BSUoS) recovers the cost of the day to day operation of the network by the System Operator. These costs depend on the 'balancing' actions that the operator may take to ensure our supply of energy matches demand.

Back to The energy network: how it works for you

Customers of an electricity supplier who are located within  the supplier's original ex-PES region.

See ex-PES suppliers.

These include supplier operating costs, and are inflated by the Consumer Price Index.

An organisation that can help consumers to switch energy tariffs.

Kilowatt-hour is a unit used to measure energy consumption in both electricity and gas.

The large energy suppliers (often also called the 'Big Six') are the companies that hold supply licences and supply most of the energy to domestic households in the GB market. They are:

Centrica plc (parent company of British Gas), E.ON UK, Scottish and Southern Energy (SSE), RWE npower, EDF Energy and ScottishPower.

All energy companies must operate under a licence condition (or exemption/exception) if they supply gas and/or electricity services. These are administered by Ofgem and relate to the Gas Act 1986 and Electricity Act 1989.

A consumer who annually uses 2.100 kWh of electricity and/or 11.000 kWh of gas.

A discount that is paid at a pre-specified point in time if the consumer does not switch energy suppliers.

The process of splitting customers, or potential customers, in a market into different groups, or segments.

The proportion of total customers (usually as proxied by the number of meter points) within a market that are registered to a particular supply group.

A consumer who annually uses 3.300 kWh of electricity and/or 16.500 kWh of gas.

A megawatt hour. Equal to 1000 kWh.

An MPAN (Meter Point Administration Number) is the number that identifies your electricity supply. The MPRN (Meter Point Reference Number) is the same thing, but for your gas supply. These numbers allow energy companies to identify your home. You’ll find them on your energy bill or you can contact your local network operator to find out.

A meter reading based on the actual amount of energy you’ve used.

Your business is classed as a 'microbusiness' if it either:

• has fewer than 10 employees (or their full-time equivalent) and the yearly turnover, or yearly balance sheet, is not more than €2 million.
• uses less than 100,000 kWh of electricity a year
• uses less than 293,000 kWh of gas a year

An amendment to the terms and/or conditions (including price, but excluding contract duration) of a consumer’s energy supply contract, mutually agreed between the supplier and the consumer. The consumer would not be obliged to accept the proposed variation. The variation can only be binding following express agreement from the consumer.

These include the costs to build, maintain and operate the gas pipes and electricity wires run by the network companies who transport energy to your property. 

Suppliers are charged by network companies for this, and pass on this cost to their customers. We limit network costs carefully though price controls. This is because you can't normally choose which network company you use.

Back to Energy market facts and figures

Network operators run the pipes and wires that bring gas and electricity to our homes and businesses. There are different owners in different parts of Great Britain. The exception is gas transmission, which is owned and operated by National Grid Gas.

Transmission network operators take energy from gas fields or power plants where it is generated and carry it on big pipes or cables nationwide and to distribution networks.

Distribution network operators run the smaller pipes or wires that take energy locally to homes and businesses. You'll usually contact them if you have a power cut or supply problem.

An entrant that does not have an incumbent customer base.

A tariff that is not a Time of Use (ToU) tariff.

The body established by the Enterprise Act 2002 (which replaced the Office of Director General of Fair Trading) with functions that include enforcing consumer protection law and competition law, reviewing mergers and conducting market studies.

We are the independent energy regulator for Great Britain. Our priority is to make a positive difference for consumers by promoting competition in the energy markets and regulating networks.

Ombudsman Services: Energy means the Ombudsman Services provided to Energy Suppliers and Energy Network Operators. The Ombudsman’s principal aim is to receive complaints made by complainants in accordance with the Ombudsman’s Terms of Reference and to consider and, where appropriate, investigate such complaints in order to encourage and/or facilitate the terms of their resolution, settlement and/or withdrawal.

Where a consumer does not receive a paper version of a bill or statement of account and would need to access the internet and use a computer or communication device.

A discount provided to a customer with online account management.

A tariff for the supply of electricity/gas which may only be entered into via a website, and/or a tariff which must be managed fully or partly by a customer via a website.

A tariff that is available to new and existing domestic customers at any given time.

Where a customer receives all communications electronically.

A supplier that owns enough stock in another supplier to have control of management and operations of that supplier.

A method by which a consumer pays for energy. Payment methods are classified into three main categories: direct debit, standard credit and prepayment.

This is based on your actual consumption and is a projection of your future yearly charge. You could compare the personal projection for your current tariff with a personal projection given to you for an alternative tariff by your current supplier, an alternative supplier or a switching site.

The Point of Connection determination activities relates to activities associated with existing Distribution Networks in the metered and unmetered connections market.

For more information visit the Point of connection sub-group page.

A method of payment where consumers pay for credit to their account. Their meter deducts credit from the account based on the amount of energy used by the consumer and the rates that apply to the consumer’s tariff.

This is the difference between the money an energy company receives from their customers and the costs they have to deliver that energy. The ‘margin’ is not just the profit energy companies make. This is because they must pay tax and fund debt payments plus other obligated costs from this money. 

A prepayment meter tariff means you pay upfront for your gas or electricity use. You can ‘top up’  using an app on your phone, by text or through a token or key card at a shop.

A limit on how much suppliers can charge you per unit of gas or electricity. Price cap levels are set by Ofgem based on how much it costs, on average, to get energy to your home.

You could be protected by:

• prepayment price cap (sometimes called a ‘safeguard tariff’)
• a default tariff cap, introduced by the UK government.

Price caps won’t limit your total bill. This will vary depending on how much energy you use.

A figure that can be used to compare the cost of the tariff you are on against alternative tariffs from your own or other suppliers. Also called the Tariff Comparison Rate (TCR). The TCR is calculated as the estimated yearly bill, divided by the amount of energy used each year by a typical low, medium or high user of electricity. The TCR takes account of any standing charge and the unit rate(s) that make up the tariff. The TCR is not based on your personal consumption and should be used as a guide only.

If a supplier increases the price of a tariff or varies any term which could cause disadvantage to the consumer, then under our licence obligations it must notify the consumer at least 30 days in advance of the date on which the price increase (or other variation) takes effect.

The most important terms of a supply contract, including the charges, duration, amount of any termination fees and any terms which may reasonably be considered to significantly affect the evaluation by the consumer of the contract under which they are supplied with energy.

The Priority Services Register is a free service provided by suppliers and network operators to customers in need. Each energy supplier and network operator maintains its own register. To be added to the Priority Services Register, you simply need to contact your energy supplier.

You can receive the services available if you:

• are of pensionable age
• are disabled or chronically sick
• have a long-term medical condition
• have a hearing or visual impairment or additional communication needs
• are in a vulnerable situation.

If you live with a child aged under five, network operators also offer priority services relevant to your needs. You may also be eligible for priority services from your supplier if you live with a child aged under five. Contact them to find out about the services they provide. 

The free services that may be available for priority services customer include:

• Advance notice of planned power cuts. If you are medically reliant on your supply you can arrange for the company that runs your local network (the network operator) to give you advance notice of planned power cuts (for example, where they plan to carry out engineering work).
• Priority support in an emergency. This could involve your local network operator providing alternative heating and cooking facilities in the event of supply interruption.
• Identification scheme. This is to reassure you that callers, for example meter readers, are genuine. Suppliers have to provide additional support to help you identify someone acting on behalf of their company, such as arranging a password or showing an agreed picture card upon visit. 
• Password protection. Network operators must offer to agree a password with you (or your representative) that can be used by any representative of the company to enable you to identify them.  
• Nominee scheme. Customers can ask their supplier to send communications (such as account statements or bills) to someone you have nominated (for example a family member or carer) who has agreed to receive them.
• Arrangements to ensure that it’s safe and practical for you to use your prepayment meter. For example, moving a prepayment meter if you are unable to access it safely to top it up.
• Meter reading services at appropriate intervals. If no person occupying the premises is able to read the meter and there isn’t anyone else that the customer can nominate to read the meter on your behalf, your supplier may be able to read it for you.
• Accessible information. Account and bill information in an accessible format, for example in larger print or braille.

See more information on the assistance available through the Priority Services Register for people in need.

Someone who buys raw material (eg timber) and processes it. They can use fuel from their own wood to process and sell on, but can also buy fuel from others to sell on. They must meet the land and emissions criteria.

This is the name we gave to the prepayment price cap when we extended it to 1 million vulnerable households who receive the government’s Warm Home Discount in 2017. This is to reflect the fact that this price cap specifically covered some vulnerable customers. Since these Warm Home Discount customers will be covered by the default tariff price cap from 1 January 2019, this price cap will revert to being called the 'prepayment price cap'.

Industry regulation without our binding licence conditions or rules contained in legislation. However, if self regulation is not operating as we would hope, licence conditions may be introduced.

A prompt to consumers that they can consider switching tariff or supplier.

Suppliers which operate in the domestic gas and electricity market but do not hold significant market share. This can refer to all suppliers other than the Big 6

Smart meters are the new range of gas and electricity meters which the government wants installed in all households and businesses in Britain by 2020. 

Through a display in your home, they give you almost immediate information on your energy use easily explained in pounds and pence. This means you can better manage what you are using and when, which could help you to save money and reduce emissions. 

Smart meters will also bring an end to estimated billing. They can communicate directly with your energy supplier in near real-time. So you won't need to wait for someone to come and read your meter, and your bills will only be based on what you've used. 

We want to make sure innovation helps consumers. So we're supporting the transition to smart meters as one of number of activities in our Smarter Markets Programme.

When you pay after getting a bill rather than by a direct debit or prepayment meter arrangement. You might do this once a month or quarter. You usually have to pay within 28 days.

The legally binding conditions that licensed gas and electricity suppliers must meet to supply to domestic and non-domestic customers, in accordance with the Gas Act (1986) and Electricity Act (1989).

A standard variable tariff (SVT) is a supply contract with an indefinite length that does not have a fixed-term applying to the terms and conditions. It’s an energy supplier’s basic offer. If a customer does not choose a specific energy plan, for example after their fixed tariff ends, they are moved to an SVT until they choose a new one. A customer can also make an active choice to select an SVT.

Our data shows that standard variable tariffs are usually more expensive than other deals available in the market. For information and advice on energy shopping, see: How to switch supplier and shop for a better deal.

A written policy and procedure that outlines broad standards of integrity and business ethics.

A fixed monthly/daily amount that you pay your electricity/gas supplier for maintenance and other costs, such as maintaining connection to the power network.

A fixed monthly or daily amount that you pay your electricity or gas supplier for maintenance and other costs, such as maintaining connection to the power network.

Where fluctuations in price through the duration of a contract are set out before the contract is signed.

These are the costs associated with running a retail energy business, including sales, metering and billing.

An additional and exceptional charge added to the usual energy charge(s). This often happens where a supplier requires a customer to pay a fee for leaving a contract before the contract end date.

This is the process of changing gas or electricity supplier. Visit our guide to switching supplier to find out more.

The costs incurred by customers in finding and switching supplier. Switching costs are classified into a variety of categories, including: transaction costs, contractual costs, uncertainty costs, psychological costs, shopping costs and search costs. In addition to the above, firms can also incur costs when customers switch supplier.

An online comparison and switching service that helps consumers to compare prices on a range of products and services.

The period in which a consumer is eligible to switch supplier, in response to an End of Contract Notification, in which they will not be subject to any Termination Fees or be required to notify their supplier of their intention to switch.

One of the key outputs of SCR launched in 2017 is the development of a Target Operating Model (TOM) to deliver market-wide half-hourly settlement. To achieve this, the following design bodies were set up:

• a Design Working Group, chaired by ELEXON, which designed the preferred TOM and transition approach. The Design Working Group concluded its work when the final report was delivered to Ofgem in August 2019.
• a Code Change and Development Group, chaired by ELEXON, which is developing the outstanding areas of the TOM designed by the Design Working Group and identifying the areas of the industry codes and subsidiary documents which require amendment to implement the TOM
• an Architecture Working Group, chaired by ELEXON, which is developing the system architecture design required to enable the preferred TOM
• a Design Advisory Board, chaired by Ofgem, which provides a strategic assessment of market-wide half hourly settlement recommendations, and advise the Ofgem Senior Responsible Owner

The Design Working Group discharged their duties when they delivered their final report in August 2019. We are now in the development phase of the TOM design, and the Code Change and Development Group and Architecture Working Group have been meeting every month since December 2019.

Updates on the work that is being carried out in the AWG and CCDG can be found in our MHHS monthly newsletter. All editions of our newsletter can be found in the Newsletter section below. If you are interested in specific areas of the detailed TOM design, links to all the papers from CCDG and AWG discussions organised by detailed design area can be found on the Electricity settlement reform page of the Ofgem website.

The package of charges and conditions that a supplier offers you for providing electricity, gas or both.

The Tariff Information Label gives you key information about your energy tariff. It aims to help you easily compare your tariff with others available. Suppliers have to give a Tariff Information Label for each of their tariffs, in a clear and easy to understand form free of charge. You’ll usually find the label on your energy bill or annual statement, and suppliers must publish a label for each of their live tariffs on their website. You can directly request it from your supplier too, and they must also provide it when informing you about the principal terms of a contract.

The label includes the key features of a tariff, which usually includes things such as:

• Supplier’s name
• Tariff name
• Tariff type (e.g. fixed or variable)
• Payment method (e.g. Direct Debit)
• Unit rate* – measured per kWh, this is the price you pay for the energy you use
• Standing charge* - a fixed monthly/daily amount that you pay your electricity/gas supplier for maintenance and other costs, such as maintaining connection to the power network
• Tariff end date (if applicable)
• Price guarantee – if the price is guaranteed until a given date this is shown here
• Exit fees – if the supplier charges a penalty for switching from a tariff before its end date, the level of the amount is shown here

You may need to provide your address or postcode to access an online Tariff Information Label, but should not need any other information.

*The label will state whether these charges are inclusive or exclusive of VAT

A method of direct marketing in which a salesperson solicits prospective customers to buy products or services over the phone.

Where part of their contract, these are the contractually agreed fees a customer must pay if they terminate their contract before the agreed contract end date.

The term Third Package refers to a package of EU legislation on European electricity and gas markets that entered into force on the 3rd September 2009. The purpose of the Third Package is to further liberalise European energy markets. DECC is primarily responsible for its transposition in Britain and had to do this by the 3rd March 2011.

Third Party Intermediaries (TPIs) are companies that can offer advice and products to assist with a range of functions including energy procurement, efficiency and management. They can include switching websites, energy brokers and energy efficiency advice providers who interact with energy consumers.

If you use a TPI as a business consumer, you may pay them directly or, more often, indirectly through your supplier. In the latter case your supplier may charge you a fee linked to your consumption, or a flat rate, which the supplier then transfers to the TPI.

Third Party Intermediaries: what your business needs to know

A tariff where the charges vary by the time when the energy is consumed, for example through different unit rates for energy consumed during the day and during the night.

This is a tariff where the price per kWh for gas/electricity will vary in reference to other prices or indices. This can be the price of another tariff from another supplier, although we are proposing these tariffs will no longer be able to track the price of tariffs offered by suppliers, but only a published stock exchange quotation or index or a financial market rate over which the supplier has no control.

Typical Domestic Consumption Values (TDCVs) are industry standard values for the annual domestic gas and electricity used by a typical consumer. You’ll find them in energy suppliers’ communications, on their website and on price comparison sites where they are used to calculate the cost of a typical energy bill.

They also underpin the Tariff Information Label (TIL) and Tariff Comparison Rate (TCR).

Below you can view representative typical domestic consumption values for 2015. The current TDCVs came into force on 1 September 2015. You can use these to more easily compare between supplier tariffs on a like-for-like basis. They provide a useful starting point, but it’s still important to find out what’s right for you based on more personalised information.

Typical Domestic Consumption Values 2015

An amendment to the terms and/or conditions (including price) of a consumer’s energy supply contract, which is provided for in the contract and is at the sole discretion of the supplier.

One kilowatt of power being used for one hour. It is the same as a 40-watt light bulb being left on for 25 hours. Also known as a ‘unit’ of energy.

The monetary amount that is chargeable in respect of each unit of gas/electricity consumed.

The additional costs involved in supplying prepayment, Warm Home Discount and default tariff/standard variable customers compared to credit customers, inflated by the Consumer Price Index.

A tariff for which the supplier can amend the standing charge / unit rate(s) at its discretion.

An amendment to the terms and/or conditions (including price) of a consumer’s energy supply contract.

Many things can make us vulnerable or put us in a vulnerable situation. You could be considered vulnerable if you:

• have reached your state pension age
• are disabled or have a long-term medical condition
• are recovering from an injury
• have a hearing or sight condition
• have a mental health condition
• are pregnant or have children under 5
• have extra communication needs (such as if you don’t speak or read English well)
• cannot safeguard your welfare or the welfare of other members in your household because of your age, health, disability or severe financial insecurity
• are eligible for the Priority Services Register – a support service for vulnerable people.

You might be in a vulnerable situation for other reasons if your situation isn’t listed. For example, if you need short-term support after a stay in hospital or have financial difficulties. If you aren't sure, always speak to your supplier or network operator and explain your situation.

Citizens Advice can also help

• Call on 0808 223 1133 or use their online webchat
• For textphone, dial 18001 followed by the helpline number.

Or in Scotland contact Advice Direct Scotland

• Visit the energyadvice.scot website
• Call 0808 196 8660 or use their online webchat
• Email energyadvice.scot.

The Warm Home Discount (WHD) is a government scheme aimed at tackling fuel poverty in Great Britain. Under the scheme, larger energy suppliers support people who are in fuel poverty or are at risk of it.

Find out more at Warm Home Discount.

A tariff that is offered by a licensed energy supplier but uses the brand name of a non-licensed entity (excluding a brand name of the corporate group to which the licensed supplier belongs). The price and terms of the tariff may replicate those of the licensed supplier or may be modified to suit the specific needs of the brand. The legal relationship between the customer and the licensed energy supplier remain unchanged irrespective of the brand utilised for sales and marketing purposes.

The "Big Six" is the name sometimes collectively given to the six larger energy companies who supply most of Britain's gas and electricity. Each of them generate electricity, and deliver both gas and electricity to our homes and businesses. They are:

- Centrica plc (three retail brands: British Gas, Scottish Gas and Nwy Prydain in England, Scotland and Wales respectively)

- E.ON UK

- Scottish and Southern Energy (SSE)

- RWE npower

- EDF Energy

- ScottishPower

Back to Energy market facts and figures

There are 14 electricity distribution network operators, owned by six ownership groups. 

There are eight gas distribution network operators, owned by four ownership groups. See below for a detailed list of the individual operators against their ownership groups. 

This is the amount energy companies pay to buy gas and electricity which they then sell to you. They may buy from the wholesale market, have a contract with an electricity generator, or be part of a company generating its own energy. Wholesale gas is often bought in advance. If suppliers don't buy enough, they may have to buy more which can be at a higher price depending on the market.