In order to locate air leakage, we use a blower door test. Before this process begins, a number of steps must first be taken; we ensure that all vents are closed, a chimney balloon is placed within the fireplace, and any extractor fans located within the home are temporarily sealed. This ensures that we close off any of the external openings to the external wall. Once this process is completed, the fan for the blower door test is then turned on and we can accurately detect air and heat leakage within your home.