This study examines the influence of heat recovery ventilators (HRVs) on energy savings in high-rise residential buildings to determine optimum operation schedules. Field measurements were conducted in two actual residential buildings, and computer simulations were performed to predict energy savings by the HRVs. Measurement results showed that energy consumption in each building was reduced when the HRVs were operated in line with recommended ventilation rates and comfortable temperature ranges. The HRVs achieved greater savings of energy during winter than summer. Simulation results showed that the HRVs contributed to the annual savings of heating and cooling energy by 9.45% and 8.8%, respectively, when the ventilators were operated continuously for 24 h. More energy was saved as the operating hours of the HRVs increased. The continuous operation of HRVs was effective for the savings of energy and to maintain recommended ventilation rates. The HRVs achieved effective energy savings and maintained necessary ventilation rates in high-rise residential buildings where natural infiltration was minimal, due to tightly sealed building envelopes. This study suggests that the influence of HRVs on the improvement of indoor air quality needs to be examined in conjunction with energy savings by HRVs. (c) 2011 Elsevier B.V. All rights reserved.