Documentation of the differential pressure measurement method

In the differential pressure measurement method, the total volume of the area to be tested must first be determined and entered into the computer. Before the measurement can begin, one must ensure that all windows and doors are tightly closed.

A large fan is placed in the front door. The remaining part of the door is sealed airtight with foil. The fan generates either a negative or positive pressure of 50 pascals inside the building. It then measures the amount of air it must move into or out of the house to maintain the pressure difference of 50 pascals.

The more leaks there are in the house, the more air the fan has to move. Such leaks can easily be located using a thermal imaging camera or a fog machine. As seen above, the smoke moves toward any opening in the wall. This occurs due to the positive pressure, as the air escapes outward.