Section 402.4.1.2 of the Florida Building Code, 5th Edition 2014 Energy Conservation now Mandates blower door testing for New Residential Construction. A blower door is a powerful fan that mounts into the frame of an exterior door. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings. The auditors may use a smoke pencil to detect air leaks. These tests determine the air infiltration rate of a building.