HC Deb 27 July 1977 vol 936 cc238-9W
Mr. Tom Ellis

asked the Secretary of State for Energy if he will publish a list in order of thermal efficiency at the point of consumption of the main forms of domestic space heating and of domestic water heating.

Dr. John A. Cunningham

Domestic heating efficiency at the point of consumption varies substantially according to type, manufacturer, age, method of installation and use, so that it is impractical to generalise. Furthermore, efficiency values on their own give a false impression of the cost and suitability of a heating system, which also depends on the initial cost, the type of dwelling, level of insulation, the price of delivered fuel or energy, the pattern of consumption, method of control, etc.

However, modern well designed and carefully controlled heating systems,

Per cent.
Space heating Electricity Radiant and convector space heaters 100
Storage heaters 80–90
Gas Radiant/Convector fire 50–60
Convector (balanced flue) 65–70
Central heating boiler 60–70
Oil Central heating boiler 60–70
Solid fuel Open fire 25–40
Open fire with back boiler 35–50
Room heater with back boiler 60–70
Central heating boiler 60–70
Water heating Electrical 75
Gas The efficiencies quoted refer to a variety of appliances. 40–55
Oil 40–50
Solid fuel 40–50

It should in addition be pointed out that the above thermal efficiencies do not include the efficiency of production, conversion and distribution of domestic fuels and energy up to the point of consumption, which varies widely between some industries.