CO2浓度拟合计算出新风量和换气次数
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Topic B3. Building ventilation, infiltration, and air distribution
Measured Air Infiltration and Ventilation Rates in Naturally Ventilated Classrooms
Peng Liu, and Xiaojian Xie*, Mei Liao, and Xiaoyu Shen Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, China
*Hale Waihona Puke Baidu
Corresponding email: xxjtulip@njnu.edu.cn
Keywords: Air infiltration, Ventilation rate, Natural ventilation, University classroom SUMMARY Measuring air infiltration and ventilation rates in college classrooms under natural ventilation conditions is of great significance for understanding and improving indoor air quality. In this paper, CO2 produced by human beings has been selected as the trace gas to measure the air ventilation rates, the concentrations of which were continuously monitored in the classrooms occupied by the teachers and students, and also after they leave. The open/close conditions of doors and windows were simultaneously recorded, as well as the number of occupants. The amount of air supply could be obtained using the two-parameter emission technique ( Stavova et al. 2006) and the least-square method to fit the curve of measured CO2 concentration changing over time during different open/close conditions of doors and windows. In this field study we found that more than 70% of the time all the doors and windows were closed during class in cold season (November, December, and March) of Nanjing. Air change rates of infiltration in most of investigated classrooms were smaller than 0.5 ACH. Ventilation rates in different classrooms when doors and/or windows open varied significantly. Opening only the doors or corridor windows could increase the ventilation rate, but can’t meet the criteria of minimum fresh air volume per person set by Chinese standards. Opening both the windows and doors at the same time could significantly increase the ventilation rate, but is not practical to improve indoor air quality in winter because of the cold climate. INTRODUCTION Most of modern humans especially the elderly and children spend about 90% of their time indoor. Indoor ventilation has a major impact on indoor air quality and human health. Many studies have shown that ventilation levels in classrooms affect thermal comfort, indoor air quality and health, and also in an indirect way the learning capacity and the performance of students. Low outdoor air supply is found to increase the risk of sick building syndrome, students’ complaints and absenteeism (Seppä nen and Fisk 2004; Deng et al. 2007; Wang et al. 2007, Sun et al. 2011). In China, classroom equipped with ceiling fans and wall-mounted split units without fresh air introduction is a much more crowded environment for students than their homes. Unlike the northern part of China, there is no heating system for classrooms during winter in many cities of hot summer and cold winter area. Thus all the doors and windows of classrooms are closed when being occupied in winter to compromise thermal comfort. Due to dense population and inadequate ventilation, high levels of CO2 concentrations are very common in many university classrooms (Liao et al. 2014), in some cases of which can be blamed on the building design. To improve the indoor air quality in the
Measured Air Infiltration and Ventilation Rates in Naturally Ventilated Classrooms
Peng Liu, and Xiaojian Xie*, Mei Liao, and Xiaoyu Shen Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, China
*Hale Waihona Puke Baidu
Corresponding email: xxjtulip@njnu.edu.cn
Keywords: Air infiltration, Ventilation rate, Natural ventilation, University classroom SUMMARY Measuring air infiltration and ventilation rates in college classrooms under natural ventilation conditions is of great significance for understanding and improving indoor air quality. In this paper, CO2 produced by human beings has been selected as the trace gas to measure the air ventilation rates, the concentrations of which were continuously monitored in the classrooms occupied by the teachers and students, and also after they leave. The open/close conditions of doors and windows were simultaneously recorded, as well as the number of occupants. The amount of air supply could be obtained using the two-parameter emission technique ( Stavova et al. 2006) and the least-square method to fit the curve of measured CO2 concentration changing over time during different open/close conditions of doors and windows. In this field study we found that more than 70% of the time all the doors and windows were closed during class in cold season (November, December, and March) of Nanjing. Air change rates of infiltration in most of investigated classrooms were smaller than 0.5 ACH. Ventilation rates in different classrooms when doors and/or windows open varied significantly. Opening only the doors or corridor windows could increase the ventilation rate, but can’t meet the criteria of minimum fresh air volume per person set by Chinese standards. Opening both the windows and doors at the same time could significantly increase the ventilation rate, but is not practical to improve indoor air quality in winter because of the cold climate. INTRODUCTION Most of modern humans especially the elderly and children spend about 90% of their time indoor. Indoor ventilation has a major impact on indoor air quality and human health. Many studies have shown that ventilation levels in classrooms affect thermal comfort, indoor air quality and health, and also in an indirect way the learning capacity and the performance of students. Low outdoor air supply is found to increase the risk of sick building syndrome, students’ complaints and absenteeism (Seppä nen and Fisk 2004; Deng et al. 2007; Wang et al. 2007, Sun et al. 2011). In China, classroom equipped with ceiling fans and wall-mounted split units without fresh air introduction is a much more crowded environment for students than their homes. Unlike the northern part of China, there is no heating system for classrooms during winter in many cities of hot summer and cold winter area. Thus all the doors and windows of classrooms are closed when being occupied in winter to compromise thermal comfort. Due to dense population and inadequate ventilation, high levels of CO2 concentrations are very common in many university classrooms (Liao et al. 2014), in some cases of which can be blamed on the building design. To improve the indoor air quality in the