Research On Indoor Air Quality In Large Shopping Malls And Ventilation Improvement Strategies

China's urbanization rate have increased by 13% over the past ten years,great development of urbanization and national economy growth highlighted the commercial buildings of construction industry.The commercial buildings,where people can have fun,go for shop or dining,their energy consumption had attracted schoars' attention.However,the indoor air quality was ignored.Owing to the multifunctionality of commercial buildings,there are many kinds of commodities and high denstity cusomers.Thus,indoor air quality problems occurred with long time operation.In this respect,the paper paied attention on the indoor air pollutant and subjective perception in large commercial building.The purpose is to get the indoor air pollution level in large commercial buildings and the characteristics of indoor air pollutants distribution,then propose the improvement strategies to enjoy the better indoor air quality in commercial buildings.The indoor air parameters(temperature,humidity,velocity,carbon dioxide,TVOC and formaldehyde)and subjective perception have been tested in two large commercial buildings in Chongqing,Kunming and Tianjing city for one year,separately.And the results showed that the indoor air quality of commercial buildings in Kunming city were better than the other two cities.But all the commercial buidlings existed over-standard test point.Specifically,the mall C1 got the highest over-standard rate of TVOC and carbin dioxide,which reached 41.9%,20.7%,separately.And the mall T1 got the highest over-standard rate of formaldehyde(13.2%).The subjective perception of indoor environment indicated that the main odor was stuffy odor and the rate of sick building syndrome was 63%.Besides,fatigue was the most common syndrome and more than half shoppers thought ventilation was the most valid methods to improve the indoor air quality in commercial buildings.At last,the MySQL database named indoor air quality of commercial building was established.It can realize the query,management and statistics functions on indoor air quality.Because of the ventilation and pollution source variation,the pollutant level varied from different floors,commodity,weekday or weekends,time periods of a day,there were three questions needed to be solved by fresh air ventilation based on the difference.Firstly,as for the two questions: one is the seriously polluted underfloor and two is the higer carbon dioxide concentrations on holidays or weekends,magnifying the fresh air ratio model can improve the indoor air quality.The last one is the higher formaldehyde concentrations when the commercial buildings just open.To solve this problem,pre-purge is valid and the time of pre-purge has been calculated.In addition,computational fluid dynamic with transient simulation has been conducted to verfy the formaldehyde distribution.These provide technical support for better indoor air quality of commercial buildings.