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Housing: Insulation

Volume 475: debated on Tuesday 29 April 2008

To ask the Secretary of State for Communities and Local Government what estimate she has made of the number of properties in England unsuitable for cavity wall insulation; what proportion of the total housing stock this represents; what reports she has received on the reasons why cavity wall insulation is inappropriate in some circumstances; and what effect such circumstances are likely to have on her Department's ability to meet its targets on improving the energy efficiency of existing housing stock. (201317)

The Explanatory Memorandum for the Carbon Emissions Reduction Target includes an estimate of the number of cavity walls in GB that can not be insulated for the following reasons:

High rise blocks of flats.

Cavity width less than 50mm (or less than 40mm) if UF foam is used.

Walls below ground level.

Finlock gutters (unless they have been lined)

Water penetration or rising damp (unless treated)

Timber, steel, concrete or stone walls.

Walls exposed to driving rain (unless the outer leaf is in good condition and appropriate to the locality).

We estimate that there are currently 7.3 million homes in Great Britain with unfilled but fillable wall cavities and around 807,000 homes with unfillable cavities, for the reasons set out above. We estimate that around 2.9 million cavities will be filled under the Carbon Emissions Reduction Target.

However, the insulation industry has informed the Department for the Environment, Food and Rural Affairs (DEFRA) that improvements in technology mean that some of these cavities can now be filled; for example, three of the main insulation companies have installed cavity wall insulation in blocks of flats up to 45m, and CIGA (the cavity wall insulation guarantee agency) has assured DEFRA that cavity wall insulation is regularly retrofitted to homes in areas of driving rain (for example, Cornwall, Shetland and the Hebrides) provided that the external leaf of the building is in good condition. We therefore believe that the figure of 807,000 unfillable cavities in Great Britain is an over-estimate.