Development of a Numerical Air Infiltration Model Based on Pressurization Test Applied on a Church

Pressurization (Blower door) test is a well-established method, performed in order to quantify the total leakage in a building envelope. However, the Blower door results are not really adequate to use when air leakage through the building envelope during natural conditions (non-pressurized) is to be estimated. A common assumption made when estimating air leakage during natural conditions, is to assume that air leakage paths are evenly distributed in the areas of the building envelope. This assumption gives quite poor numerical model results since different leakage configurations are often situated unevenly in the envelope. In order to improve the correspondence between Blower door and air leakage model results, more information on the types and locations of the leakage paths are required as input to simulation models. This paper investigates if additional information from visual inspection and IR-thermography observations at site can increase the precision when estimating air change rates due to air leakage in natural conditions. A numerical model is developed in this study by allocating leakage in various parts of the building envelope. Leakage allocation is assessed by visual inspection and IR-thermography observations at site during the Blower door test. This procedure is tested in the case study of a large single zone church. Blower door and leakage allocation results are used in the numerical model. Model results are compared with tracer gas measurements.