asked the Secretary of State for Energy how much he estimates partially insulated houses cost per annum in oil equivalent as opposed to fully insulated houses.

Taking the case of a typical post-war semi-detached house in London, full heating would require about 2·0 toe a year with partial insulation of 25 mm loft insulation only. If insulated to the standards taken in the Department's booklet "Compare Your Home Heating Costs"—80 mm loft insulation—the consumption would reduce to about 1·9 toe. The addition of cavity wall insulation, if possible, would reduce consumption by a further 0·3 toe. In practice fuel consumption depends on many factors and the extent to which it is possible to insulate dwellings varies widely.

asked the Secretary of State for Energy how much he estimates failure to insulate houses costs per annum in oil and oil equivalent.

It is estimated that savings of between3 per cent. and 4 per cent. of national primary energy consumption could be gained by a combination of loft insulation, cavity wall insulation and double glazing. This is equivalent to 6 million to 8 million toe a year. But these measures may not all be cost-effective in any particular house. The potential savings due to thermal insulation are examined in greater detail in a report by the Building Research Establishment, CP56/75.