Thermography. The effects of external factors upon thermal images. Termografering. Matningsbetingelsers inverkan pa varmebilder.

Reports an investigation of the effects of temperature differences, pressures, sun and wind conditions on a thermal image produced by thermography. This investigation is concerned mainly with measurement points associated with air leakage. Reports measurements on a single-storey timber-framed house under a pressure difference of 5,-2,-10 and -20 Pa. Finds that the importance of ahigh internal underpressure decreases with the difference between indoor and outdoor temperature and that a relatively large underpressure is required for reliable identification of leaks if the temperature difference is small. Finds that leaks are difficult to locate if there is an internal overpressure. Wind can give rise to convective air currents which are difficult to locate under calm conditios.