A recent survey of the building construction industry by the Building Commissioning Association (BCA) on the issue of duct leakage resulted in some startling statistics. Seventy-five percent of the approximately 300 respondents felt that duct leakage contributes substantially to energy loss in commercial buildings. And, 74% of the respondents also believed most of the buildings in the U.S. have significant duct leakage (greater than 15%). Duct leakage can significantly increase the energy consumption of a building, leading to increased energy bills for the owner. It increases energy costs and can result in occupant discomfort and lower productivity. This combination can transform a building intended to be a high performing building into a building that is not. So, what can be done to combat duct leakage? Test early and test often.