Heating and cooling losses from forced-air ducts can result in high energy costs, lead to thermal comfort problems, and -- in some extreme situations -- result in serious health and safety concerns. Reducing air leakage and conductive losses from ducts can be a straight-forward way to reduce energy use and improve comfort in homes. This book discusses the basics of air distribution and duct design; strategies to seal and insulate ducts in existing homes; accurate heating and cooling load calculations and HVAC equipment sizing.