Leakage measurements using unsteady techniques with particular reference to large buildings

The paper describes investigations of unsteady techniques for measuring leakage of buildings. The main investigation is theoretical. The theory used accounts for compressibility and inertia and is based on a quadratic flow equation. It is therefore an advance over what has been used in the few previous investigations. In particular, it allows uncertainties due to inertia to be assessed. The investigations cover three unsteady techniques i.e., the AC and the pulse techniques and a novel DC/AC technique. It is concluded that for most buildings, the conventional steady DC technique is preferable. However, for large buildings, the DC technique becomes increasingly inaccurate and an alternative technique is required. A novel form of pulse technique is proposed and theoretical and experimental investigations are presented which indicate that it has the potential to provide a simple and quick way of measuring the leakage of large buildings.