Reading Rick Jefferys's letter on solar heating (12 February, p 54) raises the question: whatever happened to heat recovery systems for houses?
In the late 1970s, I visited a new development of timber-frame houses in Washington, Tyne and Wear, in which heat recovery systems were installed. The system consisted of a heat exchanger which extracted heat from outgoing air and used it to heat incoming air. This was supplemented by electric heating. The houses were also triple-glazed and the roof space, walls and floor were insulated with 250 millimetre-thick rock wool. They were said to be very cheap to heat.
Such a system combined with solar heating would be very fuel efficient, so why has it not been more widely adopted? Perhaps someone could shed some light on this?
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