Experimental Investigation of the Impact of Environmental Conditions on the Measurement of Building Infiltration, and its correlation with Airtightness

The air infiltration of a building, which fundamentally depends on its airtightness, can be a significant contributor to its heat loss.  It can also be affected by other factors such as external terrain, leakage distribution, sheltering factor and environmental conditions. The infiltration rate of a detached UK house was monitored for 2 months in early 2018 using constant concentration and decay tracer gas methods under various temperature and wind conditions. Different temperature differences across the building envelope were achieved by heating up the indoor air with the assistance of fan heaters. Various wind conditions were covered by carrying out tracer gas tests continuously over a few days during which different wind conditions were captured. The external pressure distribution on each side of the building envelope was also monitored using differential pressure transducers. The impact of the wind on the external pressure distribution was investigated in order to understand how the building pressures across the envelope of the test house is affected by different wind conditions. Hence, better understanding on how the wind physically affects the infiltration can be gained. Initial results agree with previous findings that both wind and stack effects are two dominant environmental factors that affect the infiltration rate. Differential pressure measurements confirmed the relevance of wind speed and direction.