asked the Secretary of State for the Environment what he estimates would be the increase, in percentage terms, in the fabric heat loss to a heated factory of 10,000 sq m constructed with a single metal skin, compared with the same factory building constructed to a minimum current Building Regulations (England and Wales) standards.

If the factory were built entirely with a single metal skin with an insulation value (u value) of 6·5, rather than 0·7 in accordance with the present requirements, the percentage increase in the fabric heat loss would be about 830 per cent.