English

One of the main problems about air flows pattern studies remains the experimental validation of numerical codes developped for interzone air flow and polluant diffusion prediction. A few years ago, CETHIL developped a real scale experiment made of a 88m² dwelling built in our laboratory hall in a controlled climatic environment.

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.

A branched connection is a single air flow passage connecting more than two zones. Its existence in a building has not been a critical issue for the measurement of air flows of single zones, as far as the validity or accuracy of the measurement techniques is concerned. However, with the ever increasing sophistication of building air flow measurement techniques --- which include tracer gas and multifan pressurisation techniques --- and the ever increasing use of them in multizones, it becomes increasingly desirable to examine the effect of branched connections.

The external facade of a nine storey office building has been reclad with a ventilated cavity structure with a length to height ratio greater than forty. As there is little published information regarding the likely air flows within such cavities a research programme has been set-up to investigate the ventilation and energy performance of this structure. This paper will address the cavity air flows through both theoretical and full scale measurements.

Building air flow is directly related to the building energy consumption and indoor air quality. As buildings become increasingly air tight, air flow through building background cracks becomes more important, and can account for up to half of the total building air infiltration. However, background leakage is not well understood, due to the lack of appropriate measurement methods. The multi-fan guarding zone or deduction technique provides a means for testing background leakage distributions, an important parameter for characterising the background leakage.