The objective of this study is to investigate the impact of duct flow resistance on residential heating and cooling energy use in systems with PSC and ECM blowers. Experimentally determined cooling performance of a unitary air conditioner was integrated with building energy simulations to predict the annual space heating and cooling energy use in two extreme climate conditions as a result of ductworks with four different levels of flow resistance of 75, 125, 175, and 225 Pa. An analysis of building energy simulation results reveals that the use of ECM blowers can generally yield electricity savings in residential central heating and cooling systems compared with the result of using PSC blowers, but the electricity savings is strongly dependent on the reduction of duct flow resistance. (C) 2016 Elsevier B.V. All rights reserved.