Analysis of the variable heat exchange efficiency of heat recovery ventilators and the associated heating energy demand

• Published in: Energy and buildings Vol. 172; pp. 152 - 158
• Main Authors: Choi, Youn-hee, Song, Doosam, Seo, Donghyun, Kim, Joowook
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.08.2018; Elsevier BV
• Subjects: Air quality; Demand; Efficiency; Energy; Energy demand; Energy recovery; Energy recovery ventilator; Enthalpy; Field measurement; Heat exchange; Heat exchange efficiency; Heat loss; Heat recovery; Heat recovery systems; Heat transfer; Heating; Indoor air pollution; Indoor air quality; Indoor environments; Lab test; Laboratory tests; Mechanical ventilation; Outdoors; Residential buildings; Sensible heat; Simulation; Temperature gradients; Ventilation; Ventilators; Field measurement; Heat exchange efficiency; Simulation; Lab test; Energy recovery ventilator
• ISSN: 0378-7788; 1872-6178
• DOI: 10.1016/j.enbuild.2018.04.066

•Long-term measurements were taken to estimate the effectiveness of an ERV system in a residential building under actual outdoor and indoor conditions.•The heat exchange effectiveness of the ERV system fluctuated according to the outdoor temperature changes, unlike the constant effectiveness provided by ERV manufacturers.•In the simulation results, the heating load and the heating energy demand when heat exchange effectiveness was variable were 88% and 69% higher, respectively, than in case where heat exchange effectiveness was constant. Energy recovery ventilators (ERV) have become popular in Korea for their use in minimizing heat loss in ventilation and maintaining indoor air quality (IAQ). The performance of ERV systems is determined by laboratory tests under prescriptive indoor and outdoor conditions. Typically, a fixed heat recovery efficiency of the ventilation system is used in building energy simulations. In this study, in order to analyze the heat recovery efficiency of an ERV under actual operating conditions, long-term field measurements were performed in a residential building in the winter. The results showed that the enthalpy heat recovery efficiencies fluctuated between 25% and 70% depending on the outdoor conditions. The sensible heat recovery efficiencies were between 30% and 65% and were proportional to the temperature difference between indoors and outdoors. The heat exchange efficiency of ERV was not constant but varied according to changes of indoor and outdoor conditions under actual operating conditions. A simulation method was used to analyze the effect of the ERV's variable heat exchange efficiency on heating energy demand in the heating season. Two cases were analyzed. Case 2 analyzed the variable heat exchange effectiveness of the ERV based on the field measurements. Case 1 examined the fixed effectiveness proposed by the manufacturer. Simulation results showed that the heating energy demand in Case 2 was 69% higher than that in Case 1. This means that the heating energy demand may be underestimated if the heat exchange efficiency of the ventilation system is assumed to be constant in the simulation.