Jargon Buster

Our quick guide explains some of the acronyms and terms used in the energy industry.


Annual quantity

The annual quantity of gas consumed.

Calorific value

Calorific value is a measure of the energy contained in gas. It represents the amount of heat released as the gas is burned.

Climate Change Levy

This is a levy (or tax) introduced by the Government on 1st April 2001 on the use of energy in industry, commerce and the public sector. 


Distribution Network Operator. A company that owns & maintains a network for transporting electricity.

First (Primary) and Next (Secondary) rates

We work out some of our bills using two different price bands. These used to be called 'Primary' and 'Secondary' rates, now we call them 'First' and 'Next'. The threshold at which you switch from primary to secondary prices depends on your tariff. To work out how many units we charge at the Primary (First) unit price, we divide the threshold limit by 365 days and then multiply this by the number of days your bill covers. We charge everything you use after that at the Secondary (Next) rate

kWh (kilowatt-hour)

A kWh is the unit of energy used to measure electricity and gas bills. It shows how much energy is used over time. To find out more about kWh, go to 'What is a kilowatt?'

MPAN (Meter Point Administration Number)

The MPAN (Meter Point Administration Number) is your unique electricity reference number, and is used to identify your electricity supply. 

MPR (Meter Point Reference)

This is your unique gas Meter Point Reference number, and is used to identify your gas supply. Your MPR is on your gas bill, not on the meter itself.


Meter Serial Number. A number given to identify an actual meter.


Office of Gas & Electricity Markets. Regulator for gas & electricity businesses in Great Britain.


Supply start date.

Standing charge

A standing charge is a daily amount you pay for your gas and electricity. Standing charges are used to cover our costs, such as meter reading and maintenance and the cost of keeping you connected to the grid. The price per kWh is how much you pay for the energy you’ve used, we work this out by reading your meters.

What is a Tariff Comparison Rate (TCR)?

The Tariff Comparison Rate (TCR) helps you compare different tariffs across the energy market – all suppliers have to work out the TCR in the same way.

It should only be used as a guide as the TCR is based on an assumption that everyone always uses exactly the same amount of energy each year.

The number that all suppliers use for this 'Assumed annual consumption' is Ofgem’s average for medium energy users. This currently stands at 3,100 kWh/year for electricity and 12,500 kWh/year for gas.

If you use more or less energy than this, the amount you actually pay will be different. 

Here’s an example of a TCR for our E.ON EnergyPlan electricity tariff in the East Midlands where the customer pays on receipt of their bill.

An example of a TCR

After deducting any discounts such as paperless billing we can use the unit rates and standing charge for the tariff, plus the ‘Assumed annual consumption’, to work out how much an average customer would spend - the ‘Estimated annual cost’.

This is where the TCR can help you compare between different tariffs. By dividing the ‘Estimated annual cost’ by the ‘Assumed annual consumption’ the TCR gives you an easy reference to help you pick the right tariff for you.

Please be aware that suppliers can only provide TCRs for customers on a single rate meter.  If you are billed at different rates for different times of day (for example, Economy 7) you won't be able to compare tariffs using the TCR.

What is a Tariff Information Label (TIL)?

A Tariff Information Label (TIL) is your way of seeing at a glance how our energy products compare with other suppliers to make sure you get the best deal.

To find out more information about your tariff, please visit our new tariff search page.

When you use our TIL Search page you can compare tariffs with different benefits such as paperless billing. The results will also highlight the difference if you choose to pay by fixed monthly Direct Debit. If you pay a different way your tariff will say Other Payment Methods in the title.