Energy and Buildings 46 (2012) 3–13 Contents lists available at SciVerse ScienceDirect Energy and Buildings j ourna l ho me p age: www.elsevier.com/locate/enbuild Determining operation schedules of heat recovery ventilators for optimum energy savings in high-rise residential buildings Sang-Min Kim a , Ji-Hyun Lee b , Sooyoung Kim c , Hyeun Jun Moon d,∗ , Jinsoo Cho e a Institute of Technology and Quality Development, Hyundai Engineering and Construction Co., Ltd., Yongin 446-716, Republic of Korea b Graduate School of Culture Technology, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea c Department of Housing and Interior Design, Yonsei University, Seoul 120-749, Republic of Korea d Department of Architectural Engineering, Dankook University, Yongin 448-701, Republic of Korea e Department of Computer Engineering, Kyungwon University, Seongnam 461-701, Republic of Korea a r t i c l e i n f o Keywords: Heat recovery ventilator Optimum operation schedule Energy savings Natural infiltration Heat exchange Residential building a b s t r a c t 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. © 2011 Elsevier B.V. All rights reserved. 1. Introduction A building envelope is the physical separator between the interior and the exterior environments of a building that helps to maintain the comfortable indoor environment and to facili- tate the micro climate control of the building. The envelopes of high-rise buildings constructed in recent decades in Korea are made of materials with high thermal resistance. These build- ings have strong air tightness in order to minimize heat loss and gain through the envelopes. This design contributes to the sav- ings of heating and cooling energy in buildings, but it also causes important ventilation issues by cutting off natural infiltration rates through the envelopes. While the air tightness applied to build- ing envelopes is effective for energy savings, it reduces infiltration rates, and consequently results in the deterioration of indoor air quality. Due to these problems, appropriate alternatives have been applied to solve the problems caused by the tightly sealed ∗ Corresponding author. E-mail address: hmoon@dankook.ac.kr (H.J. Moon). envelopes of buildings [1–4]. In particular, ventilation systems that assure necessary ventilation rates with energy savings effectively should be adapted to the high-rise buildings and operated prop- erly, since insufficient ventilation rates are critical factors that cause severe dissatisfaction in indoor environments. It is commonly understood that heat recovery ventilators (HRVs) are effective for saving energy and maintaining necessary ventilation rates. The type of heat recovery ventilators that reuse the heat ejected from indoor spaces have been effectively utilized in high-rise buildings in coun- tries in Asia and Europe [5,6]. A variety of studies have been conducted to examine the influ- ence of heat recovery systems on building energy performance [7–12]. These studies have proved that the application of heat recovery ventilators conserves energy for heating, but that more energy for cooling is necessary to handle particular outdoor con- ditions in summer. Other studies have shown that heat recovery ventilators that are capable of exchanging latent and sensible heat have successfully reduced heating and cooling energy together [13]. However, the operation of heat recovery ventilators is ineffective when the outdoor enthalpy is lower than the enthalpy of indoor air, while outdoor humidity is higher than that of the air supplied to the conditioned space [9,14]. 0378-7788/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.enbuild.2011.10.053