Economy 7 heating

What is Economy 7?

This is a generic term to describe off-peak night time electricity (economy meaning cheap, 7 describing the 7 off-peak hours). In the case of Northern Ireland Electricity, the off-peak hours vary and can be between 1am to 8am in winter and 2am to 9am in summer.

Note that electricity customers need to apply for Economy 7. The cheap off-peak rate is not applied automatically and a standing charge applies (price listed as of October 2008 is £47.44 annually).

How storage heaters make use of Economy 7

Storage heaters spend their nights warming up bricks inside them using electricity when it is cheaper (i.e. the Economy 7 hours). During the daytime, these bricks release their heat and warm up your house. You can set the storage heaters, before going to bed to how much heat you want them to store, and gradually release, the following day.

6.82p per kW
(Economy 7 night time rate only)

Economy 7 standing charge applies of £47.44 a year
4.86p per kW

Based on 47p per litre=9.671kW
(assuming a good boiler operating at 95% efficiency and October 2008 average prices)
All prices quoted are dated October 2008

You can take advantage of being on Economy 7 by setting your washing machine or tumble dryer to come on at night and perhaps boil a kettle on the cheap before 8am. You also don’t need to remember to order electricity.

There are other considerations.

As you have to set the storage heaters the night before for how much heat you want, you can expect to be too hot one day and too cold the next as you frantically try to predict weather patterns. They also tend to be hotter earlier in the morning.

To compensate, lots of storage heaters also have another option - a built in blow heater that can be switched on or off at any time. If this is on outside of Economy 7 hours, you will be heating up your house at 16.96p per kWhr - over three times the price of oil (based on October 2008 prices).

It is for reasons like this that the Northern Ireland Housing Executive has been actively replacing Economy 7 storage heaters over the years for oil or gas. Storage heaters tend to be a cheap option and useful where space may be limited (such as in an apartment).