Economy 7

[edit] Introduction

Economy 7 (E7) is a reduced rate off-peak differential or multi-rate tariff for electricity consumed during 7 hours overnight, when the electricity is in low demand and at its base load. The tariff requires a special meter with two different readings, one low (for the night rate) and one normal (for the standard day rate). It is usually found in homes that use electricity for both heating and hot water, often because the local area does not have access to gas.

[edit] Night storage

The heating system that is usually installed alongside E7 uses night storage heaters, which contain high thermal mass materials such as bricks, which are heated overnight when the electricity rate is cheaper. They retain this heat and release it during the day, in some cases with a small electrical fan (running on the normal tariff) to act as a blow heater. In standard night storage heaters once the bricks have exhausted their heat and cooled down the the heat source has run out until it can be heated again overnight, but some models also include standard heating elements meaning they can be used during the day but at the higher tariff.

[edit] Background

The term Economy 7 was coined by Jon Marshall, first mentioned of in 1978 and recorded in the book "Electricity Supply in the UK: A chronology by the now-defunct association of nationally-owned electricity companies; The Electricity Council. "A new off-peak tariff known as the 'Economy 7' tariff was introduced in October [1978]. It featured a seven-hour night rate some 20 per cent cheaper than most night-time tariffs, made possible by economies in the night-time operation of the system."

[edit] Other similar meters and tariffs

There are also a number of other reduced rate tariffs, which are usually determined by the geographical area of location in the UK as well as the type of meter that is installed. The most similar by name and nature is the Economy 9 (E9) which offers 9 hours of reduced rate tariff, as opposed to 7 hours. Off-peak (type 1, type 2 and type U), similarly offer differing rates between day and night as does Warmwise, offering 8 hours at a reduced rate.

These types of meter and tariff systems might also be referred as a complex tariffs and complex meters, because of the different rates and ways of measuring they offer.

Economy 10 tariff (E10), similar by name is yet more complex as it offers three different rates which amount in total to 10 hours, such as; three off-peak hours in the afternoon (e.g. 1pm - 4pm), two in the evening (e.g. 8pm - 10pm) and five overnight (e.g. 12am - 5am), Heatwise runs in the Midlands on a similar principle.

It is now possible to instal smart meters that also run on economy 7, 9 or 10 tariffs although they are less common.

[edit] Related articles on Designing Buildings

• Smart electricity tariffs‎
• Can we keep the lights on.
• Changing patterns in domestic energy use FB 76
• Developing system intelligence for optimising building electricity networks
• Economy 7, 9 and 10
• Electricity generation
• Electricity supply
• Empower community energy management.
• Energy Use Intensity
• Energy targets for buildings.
• Smart grid electricity network
• The key trends making our cities greener, safer and smarter
• The Future of Electricity in Domestic Buildings
• The use of batteries to store electricity for buildings
• TV pickup