The Research On Thermal Environment And Ventilation Behaviors In Chinese Residential Buildings

Due to differences in outdoor climates,envelope thermal properties of the buildings,form and operation of the heating and cooling systems,and ventilation behaviors of dwellers,the indoor thermal environment in different regions has distinguishing features.This study comprehensively monitored indoor air temperature,relative humidity,and air conditioner and window usage in 46 apartments in nine cities across five different climate zones in China for one year.Other related information,such as building characteristic and heating and cooling system,were derived from questionnaire survey.The results found that,during the heating period,the overheated period（>24°C）in Urumqi and Shenyang accounted for 43%and 59%of the time,respectively,while the average temperature in Chongqing in winter was around 10°C.In summer,the indoor humidity ratio was over 12 g/kg for most of time in all cities except Urumqi.The results obtained in this study can provide useful information for researchers and designers to improve thermal comfort condition in Chinese residential buildings.Occupants’interaction with windows is closely related to indoor air quality,thermal environment and energy consumption in a building.Due to climatic variations as well as individual specificity,window opening behaviors tend to vary among different cities and households.This study conducted one-year monitoring measurement on window behaviors and related influential factors,such as indoor temperature,humidity ratio and CO₂ concentration in 148 apartments in nine cities across five different climate zones in China.The results show that the probability of window opening was positively correlated with interior and exterior temperature and humidity ratio,while it was negatively correlated with indoor CO₂ concentration and outdoor PM_2.5 concentration.The probability of window opening was lowest during sleeping time（23:00～6:00）and increased sharply during wake-up time（6:00～9:00）.Occupant diversity of window behaviors in southern cities was more significant than northern cities.After classifying the households into three categories in each city by using K-means clustering,a principal component logistic model was developed for each type of household.Compared with natural ventilation,mechanical ventilation is more reliable,controllable,and comfortable.However,it will cost energy to operate mechanical ventilation system.This study investigated the usage of window and operation of mechanical ventilation system in 46 apartments in ten cities across five different climate zones in China by on-site monitoring and questionnaire survey.Overall,the mean daily natural ventilation durations was larger than mechanical ventilation durations.From north to south,with the growth of outdoor temperature,natural ventilation durations increased and mechanical ventilation durations reduced.This study proposed that thermal comfort,health,and energy saving can be regarded as three motivations for ventilation behaviors.Occupants prioritize their requirement for thermal comfort over the healthy indoor air quality（IAQ）.However,if the mechanical ventilation is available,occupants were willing to spend on energy expenditures to meet the requirement for health.Based on the obtained results,suggestions were made for achieving healthy,thermally comfortable,and energy efficient ventilation in residential buildings.