§ Mr. Hastingsasked the Minister of Housing and Local Government if he will give an approximate estimate of the 23W relative efficiency in preventing heat loss from a room of a single glass window, a double glass window with an air space between, double glass window with air space and perspex between and an ordinary plastered brick wall.
§ Mr. H. MacmillanTaking an 11 in. plastered brick cavity wall as the standard, I am informed that a double glass window with perspex between and ¾ in. spacing is a little less efficient. A double glass window with ¾ in. spacing lets through about one-and-a-half times as much heat and a single glass window about three times as much. A brick wall built with lightweight or clinker concrete blocks for the inner leaf is warmer than a double brick cavity wall.