Laboratory measurements have shown that when pressure differences are applied across wall and roof elements, the majority of the pressure drop takes place across the vapour barrier . Similarly , field measurements have shown that the majority of the leakage in Norwegian buildings occurs at the joints in the vapour barrier , at wall / floor joints , around penetrations of the vapour barrier and through holes in the vapour barrier . Prior to 1980, the standard vapour barrier in Norway was 0.06 mm thick polyethylene sheeting.
This paper presents results of air leakage measurements on brick walls and concrete block walls, used as outer or inner leaf of a cavity wall. The results are obtained using a pressure box on a series of test walls. The variable parameters that are examined: workmanship, pointing of the joints andplastering of the inner leaf. Out of the results can be concluded that, in general, only a plastered wall can guarantee a sufficient airtightness.
The actual heating load of a building differs often from the designed load. One reason for this is the uncontrolled ventilation through a building envelope. The heating load of air infiltration has, in practical calculations, been calculated according to the predicted leakage flow rate and to the indoor and outdoor air temperature difference. We suggest, however, that the value of transmission heat losses should be corrected by a factor, Nusselt number, because of the thermal interaction of leakage flows and conduction heat transfer in wall structures.
It has been estimated that 15% of the energy used for building services in the United Kingdom is consumed in industrial buildings. A large proportion of this is thought to relate to infiltration and ventilation. There has been very little information produced concerning infiltration rates in industrial buildings because of the difficulty in making accurate measurements. During the past three years, British Gas has made ventilation and building leakage measurements in a number of industrial and other large buildings in the UK.
Ventilation has a considerable influence on both the indoor air quality and energy consumption of buildings. Three parameters can be identified which are of key importance in the assessment of ventilation behaviour: air change rate, interzonal air flows, air leakage characteristics. This paper describes measurement techniques which enable these parameters to be evaluated. The listof techniques presented is not exhaustive and the descriptions given are not particularly detailed.
Sections include: measuring procedure air tightness of facades; evaluation of measuring air tightness in practice; infrared thermography; thermographical research in air tightness, ability to detect air tightness deficiencies with thermography; ability to quantify air leakage; architectural analysis of airtightness deficiencies; recommendations.
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