Developing a combined intake and exhaust vent for heat recovery ventilation in cold climates

Abstract

Heat recovery ventilation systems have become increasingly popular in modern residential buildings, particularly in cold climates. This has led to the research and development of supporting technologies, such as combined intake/exhaust vents. Conventionally, the intake and exhaust airflows of a heat recovery ventilation system use separate vents and penetrations in a building's envelope; combined intake/exhaust vents package these airflows together and use only one penetration. This simplifies heat recovery ventilation system installation and can lead to higher operating efficiencies; the implications are reduced up-front and operating costs as well as broadened access to heat recovery ventilation. Unfortunately, in cold climates, existing combined intake/exhaust vent designs are susceptible to frost accumulation, a mode of failure. The aim of this work was to develop a combined intake/exhaust vent more suitable for cold climate use: the Arctic Dual Hood. The design was developed in iterations informed by experimentation. These experiments included climate chamber evaluations and field performance comparisons. This design process produced a functional prototype with favorable frost mitigation characteristics compared to an existing combined intake/exhaust vent design, as determined through the field performance comparisons. Additionally, this prototype observed the constraints and met the performance requirements imposed by the American Society of Heating, Refrigeration, and Air-Conditioning Engineer's Standard 62.2: Ventilation and Acceptable Indoor Air Quality in Residential Buildings.