The Research About Ventilation And Indoor Pollution In Residential Buildings In Severe Cold Climate Regions Of China

With the development of urbanization,the construction area of new residential buildings in China has been increasing,and furniture decoration materials are also widely used indoors.For residents in the severe cold regions of China,the indoor air quality is not only affected by the pollution of the decoration,but also affected by the severe outdoor smog during the heating season.Poor indoor air quality will greatly affect the health of occupants indoors.Understanding the indoor pollution under the two ventilation modes of natural ventilation and mechanical ventilation is of great significance for proposing effective energy-saving ventilation means for the severe cold climate zone through the year and improving the existing ventilation problem.This study conducted a field test in 22 houses during a whole year in Urumqi,a cold climate zone,to understand the indoor formaldehyde concentration in daily and closed conditions.At the same time,4 natural-ventilated apartments and 6mechanically-ventilated apartments were selected for the construction of the Internet of Things system,and a two-year monitoring project was planned.The system includes air quality sensors,door and window behavior monitoring sensors,and mechanical ventilation system opening and closing monitoring sensors.Due to the promotion of energy-saving work,the apartments in Urumqi has good airtight performance,low infiltration air exchange rate,and high indoor formaldehyde concentration.When the ventilation is insufficient in winter,the minimum air exchange rate in the room should be guaranteed.In winter,the minimum average monthly temperature reaches-15°C,and the absolute humidity outdoor is only 1²g/kg.At the same time,due to heating requirements,outdoor particulate matter pollution is serious,and mechanical ventilation is more suitable.In the current residential buildings with mechanical ventilation systems,50%of the nighttime indoor PM2.5 concentration is higher than 35?g/m³.Statistical analysis results shows that PM2.5 concentration I/O ratio for all apartments when opening the mechanical ventilation system is about 0.35.There are 3 months in the heating season that the indoor relative humidity less than 30%in the night accounts for more than 50%of the nighttime.Therefore,this paper recommends that in the severe cold climate regions,residential buildings should be equipped with a mechanical ventilation system with sensible heat recovery module,meanwhile increasing the particulate matter efficiency ePM_2.5 of the air filters to more than 80%,and adding auxiliary humidification means indoors,people's health and comfort requirements can be achieved by this.In the summer and transitional seasons,the outdoor wind level is less than or equal to 2,accounting for 86.2%.In July and August,the outdoor average temperature is 24.5°C and 22.3°C,respectively.The average bedroom temperature is27°C and 26.7°C.The indoor and outdoor temperature difference within 6?accounted for 79.8%of the time.For window-opening and window-closing conditions in the summer,the indoor CO₂ concentrations are 456±77ppm and560±275ppm,respectively,and the PM2.5 concentrations are 9.9±8.5?g/m³ and8.0±8.2?g/m³,respectively.Regardless of outdoor pollution or meteorological conditions,it is recommended that natural ventilation is suitable in summer.