Determining the adventitious leakage of buildings at low pressure. Part 2 : Pulse technique

In the second part of this paper the technique that allows the direct measurement of Q4 to reduce the uncertainty by a factor of three or more is described. The key factors are : measurement of Dp a short time before and after the pulse, choice of the shape and duration of the pulse, minimising the variation of Dp during the quasi-steady period. Example of measurements are presented and comparisons are made too between the new technique, the conventional steady one and a theoretical model. Results and conclusions are presented.