Development of a multi-tracer technique for observing air movement in buildings.

A method for following air movement within buildings, which uses several different tracer gases simultaneously, has been developed. The method consists of the following sequence of operations: 1) up to four tracer gases are released at various points within the building, 2) the mixture of gases is sampled at any number of positions in the building as a function of time since the release, 3) the samples are chemically analysed to produce curves showing the concentrations of each gas stepping through time and space, and 4) the variations in gas concentrations are used to evaluate air movement through the space. Specific experiments to illustrate such air movement have been carried out and these are summarised.