An investigation of the potential use of thermography for building air leakage measurements.

The heat loss associated with the external fabric of a building has been greatly reduced by the increased levels of modem insulation, but heating losses associated with cold external air flowing into a building via leakage points in the external facade are still a major problem. Some ventilation is necessary but a detailed knowledge of this leakage would enable the major heat loss routes to be blocked. A crack has been studied which has hot air of a known temperature and flowrate passing over it. This has been modelled using a finite element analysis enabling the flowrate to be calculated from the measured temperatures. Additional cracks made from various building materials have been studied using infra-red thel-mography in order to establish the flowrate and therefore quantify the air leakage. A more extensive mathematical model is now being developed using computational fluid dynamics to predict the airflow based upon a knowledge of surface and air temperatures.