Performance Evaluation Of Residential Ventilation Accompanied With Air Purification In Northern China

Ventilation is commonly thought helpful for improving indoor air quality.However,this may not be true when the outdoor air is polluted.For example,in event of fog and haze in developing countries,the outdoor particulate matters?PMs?can be drawn into rooms by ventilation,resulting in poor indoor air quality.In such circumstance,ventilation must be accompanied with indoor particle filtration.An appropriate mean of ventilation and air cleaning shall assure acceptable indoor air quality and good performance in energy consumption and economy.However,most studies on ventilation and air purification assumed that the outdoor air is clean enough.Few studies addressed comprehensive evaluation of the ventilation together indoor particulate filtration in perspective of indoor air quality,energy consumption and economy.This investigation adopted EnergyPlus to evaluate residential ventilation together with air cleaning.An air-filtration module was added to the EnergyPlus software to predict indoor pollutant concentration when adopting air purifications.The accuracy of the EnergyPlus software was validated with the measurement data obtained in a test room.Then the validated software was adopted to evaluate residential ventilation with air filtration in a typical residential apartment in northern China.The ventilation schemes included the natural ventilation without air cleaning,natural ventilation with indoor particle filtration,mechanical ventilation with particle filtration,and the hybrid mode of natural and mechanical ventilation.The evaluation parameters include air change rate,CO2 concentration,PM2.5 concentration,indoor temperature,HVAC energy consumption,air-cleaning energy,ventilation energy consumption and energy bill,etc.The central and decentralized mechanical ventilation and the heat recovery performance were evaluated as well.Dynamic outdoor air rate and dynamic clean air delivery rate?CADR?for demand control were proposed to ensure that both indoor CO₂ and PM2.5 concentrations exactly meet the minimum standards.Finally,the ventilation and air purification schemes in five climate zones in China were briefly evaluated,and the affordable ventilation and indoor air quality control strategies were suggested.The results reveal that the extended EnergyPlus software was able to predict transient ventilation rates,indoor PM2.5 concentrations,air temperatures,and air-conditioner energy in good agreement with the measurement data.Air cleaners must be utilized in regions with heavy outdoor air pollution,such as in northern China.The natural ventilation together with demand-controlled particulate filtration has the lowest operating cost,though the ventilation rate may occasionally be insufficient.It is thus still necessary to check whether the chemical gaseous pollutant concentrations exceed the limit.Among the mechanical ventilation modes,the decentralized systems have a large potential to minimize utilities.The mechanical ventilation in demand-controlled operation and its hybrid with natural ventilation can further reduce the energy consumption.For mechanical ventilation with a decent outdoor air rate just getting indoor CO₂ concentration equaling to or slightly below 1000 ppm,the heat recovery does not show favorable potential to minimize the operating cost.