air infiltration rate

Building air infiltration rate is required as an important input in the calculation of building heat loss. Tests to directly measure infiltration rates are complex and time-consuming to perform, and are therefore usually substituted with an airtightness test as a more efficient alternative. An empirical ratio, or sometimes an infiltration model, is then used to predict the building infiltration rate from the measured airtightness value. For instance, in the United Kingdom the building air permeability measured by a steady pressurisation test and reported at 50 Pa

In a cold climate such as of Montreal the air infiltration through the exterior envelope of a house has a significant impact on the heating energy consumption and cost. Although the reduction of the air infiltration rate to the level of new well-built houses can lead to the reduction of heating energy cost, the present cost-effectiveness of its implementation in the existing houses is low. The evaluation of the environmental impact of this energy conservation measure is performed using the GWP (Global Warming Potential) index.

Residential air infiltration rates predicted by a detailed multizone computational model are compared with those predicted by a single-zone model. The multizone model is created using the public domain program CONTAM96, which allows the user to break the house into a number of Zones connected to one another and the outdoors by leakage paths with user-defined characteristics. Actual floor plans for a ranch-style house and typical published leakage characteristics of residential building components are used to construct a very detailed model with roughly 2,000 zones and 7,000 leakage paths.