Please note that this is a scanned copy of a paper published in 2000, so the text is not as clear as in documents created as pdf files.

Positive input ventilation is the usual name for systems in which ’fresh’ air is supplied to a dwelling from the roof space by means of a fan. It was originally developed in the 1970s to deal with condensation in dwellings without adversely affecting the operation of open-flued combustion appliances. While there is considerable anecdotal evidence that the installation of these units can improve indoor humidity conditions, measurements of performance have been few. This paper gives a summary of the results from performance measurements made in a BRE test house and in 15 occupied dwellings. It will be of particular interest to dwelling designers, landlords and domestic property managers. 8 pages.