Thermal bridges are parts of the building envelope where, due to the two-dimensional or three-dimensional character of the heat conduction, either the inside surface temperatures are rather low, which can cause condensation, or the heat losses are rather high. In this paper thermal bridges are analyzed by numerical methods, shortly described in the first section. They are based on energy balance techniques.
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 concern that a large number of housing units across Canada, and in particular, through Atlantic Canada are exposed to potential damage from wood rot due to moisture trapped within exterior walls caused a joint task force of Canada Mortgage and Housing Corporation and Canadian Home Builders Association representatives to address the "drying of walls" issue. Included in their mandate was a field research project in Atlantic Canada. The project, undertaken by Oboe Engineering Ltd. and AD1 Limited.
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.
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