Abstract
Air-to-air heat/energy recovery ventilators can effectively reduce the cost associated with ventilating a home. However, high indoor moisture levels, in conjunction with extreme temperature differences between the outdoor and indoor air can cause frost accumulation in the mechanical equipment, leading to performance degradation or failure. In this research, a demonstration house using a heat recovery ventilation system in Iqaluit, Nunavut, Canada was used to compare the performance of two frost control techniques: recirculation and electrical preheat. The advantages and disadvantages of each method are outlined to highlight the need to adapt southern strategies to ensure system functionality in the Arctic. The system was equipped with a heat recovery ventilator (HRV) with built-in recirculation technology to defrost the HRV, as well as two electric preheaters that can be used instead of recirculation and prevent frost formation. Between December 2018 and April 2019 the ventilation system’s performance was monitored for seven weeks while using either recirculation or electrical preheat. The experiments showed the ventilation system equipment consumed more absolute energy with electrical preheat than with recirculation as the frost control technique. However, when using recirculation, the ventilation system experienced more losses throughout the ventilation system, causing the whole building to consume more energy due to an increase in energy consumption by the home’s heating system. Moreover, the quantity of outdoor air that was restricted while using recirculation made electrical preheat the superior option for this ventilation system design. The energy use of the ventilation system with electric preheat enabled was 35% lower on a per volume of outdoor air basis. Contrary to some belief that preheating is a poor approach for frost control in heat/energy recovery ventilators, this research finds that preheating can be a more energy efficient method to provide ventilation if controlled well.
Highlights
An Inuit Health Survey evaluated 1,901 homes in northern Canada and found 20% contained mould [1], indicating a need for proper ventilation
The performance of the ventilation system when using preheat was adjusted by scaling the energy consumption of the two electrical preheaters based on the temperature difference between the preheater setpoint and the measured outdoor air temperature for both test periods
It is often thought that preheat consumes more energy than other frost control methods, an experimental study in Iqaluit, Nunavut, Canada showed that this method can be acceptable if controlled well
Summary
An Inuit Health Survey evaluated 1,901 homes in northern Canada and found 20% contained mould [1], indicating a need for proper ventilation. High indoor moisture levels, in conjunction with the extreme temperature difference between the outdoor and indoor air temperature can cause problems, such as frost accumulation in the mechanical equipment, which can cause the performance of equipment to degrade [3] or system failure [5]. For this reason, frost control methods should be used to ensure ventilation systems maintain functionality in cold climates. Some research has been conducted to evaluate the performance of individual frost control methods; a limited amount of research has been conducted to compare the performance of frost control methods within ventilation systems in extremely cold climates
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