A ventilator that responds to outdoor conditions for ventilation and air filtration

Abstract

Because of haze and fog in some countries, the outdoor air is polluted and cannot be directly drawn into rooms for ventilation. A ventilator with air filtration may be required. However, as outdoor particulate concentrations vary greatly with time, it is not ideal to operate high-efficiency particulate air (HEPA) filtration continually. This investigation proposed a ventilator with multiple modes of ventilation and air filtration. The ventilator could be switched between modes according to the outdoor and indoor air conditions. The ventilation rate and indoor particle concentrations in a test room equipped with the proposed ventilator were modelled by the EnergyPlus software program and validated with experimental data. The validated model was then used to evaluate indoor air quality and energy consumption in a hypothetical apartment located in each of five different climatic zones in China. The performance of the proposed ventilator was compared to that of a market-available outdoor air blower. It was found that to obtain the same acceptable indoor air quality, the necessary operating time for the proposed ventilator in the HEPA filtration mode was approximately 70% shorter than for the outdoor air blower, and the ventilator required approximately 30% less operating energy. In some southern cities in China, mechanically driven medium-efficiency filtration was sufficient to reduce the PM2.5 concentration to the acceptable level.