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Summer Investigation on Indoor Environment of Residential Buildings in Beijing and Other Four Cities

Summer Investigation on Indoor Environment of Residential Buildings in Beijing and Other Four Cities In order to understand the actual conditions of urban residential indoor environment, indoor thermal comfort and indoor air quality in Beijing during the summer season, the investigation of indoor environment was carried out in Beijing, from August 21 to August 25 of 2002. Results of this investigation were compared with the results in other cities, which was already reported. The questionnaire revealed the life style within residences of summer season, the types of air-conditioners used etc. This field survey showed that the indoor thermal comfort during the mid-day, evening hours and sleeping time in Beijing felt outside the ASHRAE comfort zone and the concentrations of formaldehyde and VOCs were relatively high in some houses. Keywords: China; indoor environment; residential building; questionnaire investigation; field measurement Authors have previously reported the winter and summer surveys of indoor thermal environment of urban 1. Introduction residential buildings in China [1, 2]. Energy consumption of China has been increasing The purpose of this survey is to look into the actual rapidly due to the recent economic growth and conditions in urban residence of Beijing during the development. This leads to serious environment summer period. The apartment houses under problems such as global warming, air pollution and acid investigation were located in urban areas of Beijing. A rains. In residential buildings of developed countries, questionnaire investigation together with measurements energy consumption used for space heating and cooling of indoor temperature, humidity and air quality were plays an important role in the total residential energy done in the summer of 2002 for Beijing. Table 1 shows consumption. On the other hand, indoor air quality has caught attention of the public in China. Volatile organic compounds (VOCs) and carbonyl compounds are a group of major indoor air pollutants that has been associated with many health effects including cancer (WHO1987). It is suspected that VOCs and carbonyl compounds are the major factor for “sick building syndrome” (SBS) (Molhave et al. 1986). In order to estimate the future trend of the residential energy consumption and indoor environment in China, it is necessary to understand the situation of the usage of facilities, the indoor thermal conditions and air quality. *Contact Author: Hiroshi Yoshino, Graduate School of Engineering, Tohoku University, Aoba 06, Sendai 980-8579, Japan Tel:+81-22-217-7883, Fax:+81-22-217-7886 E-mail:yoshino@sabine.pln.archi.tohoku.ac.jp Fig.1. Location of Beijing and (Received November 8, 2003 ; accepted April 6, 2004) the cities for measurement. Journal of Asian Architecture and Building Engineering/May 2004/54 47 the summary of this survey. Figure 1 shows the location The passive sampler suspended on breast for measuring of Beijing and the cities for measurement. Figure 2 personal exposure is shown in Fig.3. The passive gas shows the climograph [3] of cities where we have tubes (8015-066, Shibata Scientific Technology Ltd, investigated. For the climate in August, Beijing is very Japan) for VOCs and the 2, 4-dinitrophenylhydrazine hot and humid. (DNPH) cartridges (Xpsoure, Waters Ltd, USA) for carbonyl compounds were used in this study. These 2. Outline of Survey samplers for the indoor measurement were put in the 2.1 Questionnaire and Temperature Measurement living room. The samplers for the personal exposure In this study, an identical questionnaire and two liquid were fixed at the breast of household. The samplers for crystal thermometers [4] were distributed to the families the outdoor measurement were fixed inside an aluminum or relatives of teacher, the old boys of local university. flexible duct for protecting against solar and sky This method is the same as the previous investigation radiation. used [2]. The contents of the questionnaire are classified All these measurements were done in five consecutive into six key elements and tabulated in Table 2. Each days during the investigation period. family was requested to fix two liquid crystal thermometers onto the wall at a height of 1.1m above the floor in the bedroom and living room of their houses. The measurement was carried out in three different sections of five consecutive days from 6a.m.-8a.m. (morning), 11a.m.-1p.m. (mid-day) and 7p.m.-9p.m. (evening). The family was required to record the temperature readings from the liquid crystal thermometer within the interval of each of the section. The questionnaire was also completed by the family. 2.2 Measurement Detail In Beijing, several families within the distributed families were selected for further measurement. In this further measurement, three small data loggers with sensor were used to record the measurements of temperature and humidity for indoor and outdoor. Each sensor for the indoor measurement was mounted on supports at a height of 1.1m from the floor level in living room and bedroom. The sensor for the outdoor measurement was fixed inside an aluminum flexible duct in order to prevent solar and sky radiation. Regarding the measurement of air quality, passive sampling was applied in order to investigate the indoor Fig.2. Comparison of the climographs air concentration, the outdoor air concentration and the of major cities in China. personal exposure of VOCs and carbonyl compounds. Table 1. Summary of This Survey Table 2. Contents of The Questionnaire Survey 48 JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 3. Results of Questionnaire Survey 3.1 Characteristics of Buildings Figure 4 shows the floor areas of apartment unit in 2 2 Beijing. The floor areas range from 40 m to 140 m , with average area of 99.8 m . Figure 5 shows the height of building, in terms of number of stories in Beijing. Most buildings have the number of stories from 15 to 20, with average stories of Figure 6 shows the energy source for hot-water supply of apartment unit in Beijing. About 70% of the families use the town gas from natural gas, and 15% of the Fig.6. Energy for hot-water supply. families use electricity for hot-water supply. 3.2 Lifestyle Annual income is shown in figure 7. The number of effective replies is 49, that is 54% of collections. Many Fig.7. Annual income. Fig.3. Passive sampler suspended on breast for measuring personal exposure. Fig.8. At home ratio on weekdays and weekends. Fig.4. Floor areas of apartment unit. Fig.9. The relationship between occupantsí clothing and indoor Fig.5. Number of building stories. temperature in the evening. JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 49 residence replies forty thousand to sixty thousand. conditioners are not used at about 36% of the families Figure 8 reveals that 70-82% of residents in Beijing for a typical summer day. On the other hands, 61% of remain at home during the weekday from 8 a.m. to 5 the families use the air-conditioners. p.m.. During lunch hour from noon to 1 p.m., 82% of (3) Period of using air-conditioning the members of family stayed at their residences because Among the five cities, the period of using air- many residents prefer to return home for lunch. On the conditioning in Beijing and Xi’an are the shortest, as other hands, more than 90% of the residents remain at shown in Fig. 13. Based on the 50% line in Fig. 13, the home during weekend. period of air-conditioning used in Beijing is 2 months, The clothing worn by the occupants, male and female, and shorter than in Hong Kong, Shanghai and Changsha. in the evening is shown in Fig. 9, in terms of thermal From this survey, it is found that the adoption of air- resistance of clothing (clo) that was calculated by the conditioning in the cities except Hong Kong commences questionnaire for clothing. The average clo values for in the same months, however, the ending time of using male and female are 0.24 and 0.32 respectively. The clo values of male are lower than the female. 3.3 Air-conditioning and Its Usage [2] (1) Possession ratio of air-conditioner A comparison of the possession ratio of air-conditioner is given in Fig. 10 which includes the result in Beijing and other cities. About 80% of the families in Beijing have equipped air conditioners in both living room and bedroom, and most of them are split unit type. The type of air-conditioner equipped is shown in Fig.11. In Shanghai, investigation has been dane in 1998. But, it is reported by Long et al. [5] that the saturation level of air-conditioner in 2002 is 96.8%. (2) Cooling method Figure 12 shows the ratio of cooling method. The air- Fig.12. Ratio of cooling method. Fig.10. Ratio of air-conditioner equipped Fig.13. The period of using air-conditioning. in Families. Fig.14. Ratio of air-conditioner used in Families for a typical Fig.11.Type of air-conditioner equipped. summer day. 50 JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino air-conditioning in Beijing and Xi’an finishes half a the temperatures are betweenFig.19. The relationship month or a month earlier than in Changsha and Shanghai. between indoor and outdoor temperatures for This is due to the difference of the geographic location measurement period.Fig.20. The comfort zone of where Beijing and Xi’an belong to the cold region in ASHRAE in summer and indoor thermal China. environment.Fig.18. Results of the change of (4) Ratio of air-conditioning used for a typical temperature and humidity for an apartment. 21.5 C - summer day 30 C, and the changes are small in comparison to the Figure 14 shows the rate of air-conditioning used in outside temperature. From daytime to the evening, the five cities for a typical summer day. In comparison with Beijing, Xi’an, Changsha and Shanghai along, two peaks are seen in these cities during the daytime from noon to 3 p.m. of 50-70% and in the evening from 5 p.m. to 11 p.m. of 70-90%. Although the indoor temperature during the daytime is higher than in the evening, the usage of air conditioning is low. This is due to the fact that fewer residents stay at home during such time of the day. On the other hand, in the situation of Hong Kong the usage peak of air-conditioning is found throughout the night until morning. In comparison with the cities except Hong Kong, the lowest usage rate obtained in Hong Kong at 11 a.m. is lower than those observed in Beijing, Xi’an, Changsha and Shanghai at Fig.15. Operating time of air-conditioner. the same time on the day. (5) Operating time Figure 15 shows the operating time of air-conditioner per a day in Beijing. Some houses do not use air- conditioner on one hand and some houses use nearly 20 hours. The average of operating time is 9.8 hours. (6) Predetermined temperature Figure 16 shows the predetermined temperature of air- conditioner in Beijing. The predetermined temperature o o o ranges from 20 C to 30 C, with average area of 25.2 C. 3.4 Results of Indoor Temperature Measurement by Liquid Crystal Thermometer Figure 17 shows the average values and standard deviations of the temperatures in the living room, bedroom and outdoor of residents in the five cities of China in the evening. The temperatures of the living Fig.16. Predetermined temperature room in Beijing are almost the same as the bedroom, of air-conditioner. and the average is about 27 C, which is also higher than the outdoor. The situation of the indoor temperatures in Beijing is the similar to Xi’an. The temperatures of the living room in Shanghai are the highest in the five cities. 4. Results of Field Measurement 4.1 Indoor Temperature and Humidity Measurements were taken in 5 consecutive days in Beijing from August 21 (0:00 hour) to August 25 (24:00 hour) in 2002. Less families use air-conditioning during the measurement period in Beijing. However, some families are found using air-conditioning for a few hours during the measurement period. House-A is one of such houses and the result of the measurements at House-A is shown in Figure 18. House-A was built after 2000, and its outer wall is made of reinforced concrete with internal insulation of 50mm. Air-conditioners are set in the living Fig.17. Average values and standard deviations in the living room, bedroom and outdoor. room and bedroom. In both living room and bedroom, JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 51 indoor temperatures are lower than the outdoor periods. The variations of indoor relative humidity are temperature. This family uses the air-conditioners in within the range of 38%RH - 80%RH in both rooms. living room during the evening but in the bedroom during The indoor absolute humidity shows almost the same the sleeping hours. Therefore, the temperature, relative value as the outdoor except the operating time of air- humidity and absolute humidity are lower during these conditioner, and the difference is within the range of Fig.18. Results of the change of temperature and humidity for an apartment. Fig.19. The relationship between indoor and outdoor temperatures for measurement period. Fig.20. The comfort zone of ASHRAE in summer and indoor thermal environment. 52 JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 7g/kg’ - 18.7g/kg’. China. All of the personal exposures of formaldehyde 4.2 Relationship Between Outdoor and Indoor are higher than 80 mg/m . Figure 22 shows that the Temperatures [2] indoor toluene concentration is approximately between 3 3 Figure 19 shows the relationship between indoor and 25 mg/m and 405 mg/m . The other compounds are outdoor temperatures in the five cities during the shown in Table 3. The source of formaldehyde and VOCs measurement period. The sleeping hours, daytime and are expected to be indoor because of indoor evening are specified as 0:00-4:00, 12:00-16:00 and concentration/outdoor concentration ratios (I/O) are 18:00-22:00, respectively. Each plot means an average larger than 1. Most of indoor concentration/personal value during each period of each day. exposure ratios (I/P) are about 1. The concentrations of In Beijing, the temperature in living rooms is lower these chemical compounds were relatively higher in than the outdoor temperature during daytime. However, newly constructed houses. it becomes the same in the evening as outside temperature. In bedrooms, the temperature during sleeping time is higher than the outdoor temperature, except a few families that used the air-conditioners. 4.3 Evaluation of the Indoor Thermal Environment Based on Comfort Index [2] Figure 20 shows the comfort zone of ASHRAE [6] in summer and indoor thermal environment. Indoor temperature and humidity are in the ranges of 26 C - 30 C and 50%RH - 70%RH at daytime, night time and sleeping time. The indoor thermal condition of these three periods in the case of Beijing is outside the ASHRAE comfort zone. However, ASHRAE comfort zone is used under the situation that summer clothing is Fig.21. Formaldehyde concentration. light slacks and a short-sleeved shirt or a comparable ensemble with an insulation value of 0.5 clo for air movements less than 0.25 m/s. The temperature boundaries of the comfort zone can be shifted -0.6 C per 0.1 clo for clothing levels other than 0.5. o o Accordingly, it can be shifted to 1 C - 2 C high temperature side, considering clothing levels, and the thermal condition of a few families can be included in the comfort zone. Many occupants evaluated that indoor thermal environment in summer was ‘neutral or slightly hot’ during daytime and night. 4.4 Indoor Air Quality Figure 21 reveals that the indoor formaldehyde 3 3 concentration is between 14 mg/m and 898 mg/m . Formaldehyde concentration in four houses exceeds the Fig.22. Toluene concentration. standard, set as 80 mg/m by the National Standard of Table 3-1. Organic Compound concentration. JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 53 Table 3-2. Organic Compound concentration. contract No. 13574007. The authors would like to thank 5. Conclusions Prof. Rongyi Zhao (Dept. of Building Science School Questionnaire investigation for the indoor living of Architecture, Tsinghua University) and the old boys conditions together with field measurement were carried of Tsinghua University, Tongji University and Tohoku out to the urban residents (family type) of Beijing in the University for their great cooperation during the summer of 2002. Based on the results from this study, investigation. The authors also express their thanks to the conclusions are drawn as follows: Miss. Haihong Lou (Atmax Co. Ltd.) for providing her 1) Air conditioner type used in Beijing is mostly the split- data results and her advises. unit type. About 80% of the households in Beijing have air conditioners equipped in living room and References 1) Hiroshi Yoshino and Haihong Lou (2002), Indoor Thermal bedroom. Environment of Residential Buildings in Three Cities of China, 2) The air-conditioning operation period is from June to Journal of Asian Architecture and Building Engineering, Vol. 1, September. During the day, the peak period in No. 1, 129-136. operating the air-conditioning is in the daytime and 2) Hiroshi Yoshino, Shan Guan, Yu Fat Lun, Takayuki Shigeno, evening. Yasuko Yoshino and Qingyuan Zhang (2002), Summer Survey on Indoor Thermal Environment of Urban Residential Buildings in 3) Indoor temperature and humidity are in the ranges of China, Journal of Asian Architecture and Building Engineering, 26-30 C and 50-70 %RH at daytime, night time and Vol. 1, No. 2, 65-72. sleeping time. Many occupants evaluated that indoor 3) National Astronomical Observatory (ed.) (2001) Rika nenpyo thermal environment in summer was ‘neutral or (Chronological Scientific Tables), Maruzen Co., Ltd., Vol. 74 (In slightly hot’ at daytime and night. Japanese). 4) Yoshino H., Hasegawa F., Sawada K., Ishikawa Y., Akabayashi S., 4) Formaldehyde concentration in four houses exceeds Kikuta M. (1984), Analysis on regional characteristics of winter the criterion, set as 80 mg/m by the National Standard thermal performance and occupants' behavior of detached houses of China. in Tohoku city area, Transaction of the Architectural Institute of Japan, No. 345, 92-102 (In Japanese). 5) Weiding Long, Ting Zhong and Beihong Zhang (2003), Acknowledgements SITUATION AND TRENDS OF RESIDENTIAL BUILDINGS This study is supported by The Ministry of Education, ENVIRONMENT SERVICES IN SHANGHAI, Proceedings of The Culture, Sports, Science and Technology under the th 4 international Symposium on HVAC, Beijing, China, 493-498. 6) ASHRAE HANDBOOK, FUNDAMENTALS (2001). 54 JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Asian Architecture and Building Engineering Taylor & Francis

Summer Investigation on Indoor Environment of Residential Buildings in Beijing and Other Four Cities

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Taylor & Francis
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© 2018 Architectural Institute of Japan
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1347-2852
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1346-7581
DOI
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Abstract

In order to understand the actual conditions of urban residential indoor environment, indoor thermal comfort and indoor air quality in Beijing during the summer season, the investigation of indoor environment was carried out in Beijing, from August 21 to August 25 of 2002. Results of this investigation were compared with the results in other cities, which was already reported. The questionnaire revealed the life style within residences of summer season, the types of air-conditioners used etc. This field survey showed that the indoor thermal comfort during the mid-day, evening hours and sleeping time in Beijing felt outside the ASHRAE comfort zone and the concentrations of formaldehyde and VOCs were relatively high in some houses. Keywords: China; indoor environment; residential building; questionnaire investigation; field measurement Authors have previously reported the winter and summer surveys of indoor thermal environment of urban 1. Introduction residential buildings in China [1, 2]. Energy consumption of China has been increasing The purpose of this survey is to look into the actual rapidly due to the recent economic growth and conditions in urban residence of Beijing during the development. This leads to serious environment summer period. The apartment houses under problems such as global warming, air pollution and acid investigation were located in urban areas of Beijing. A rains. In residential buildings of developed countries, questionnaire investigation together with measurements energy consumption used for space heating and cooling of indoor temperature, humidity and air quality were plays an important role in the total residential energy done in the summer of 2002 for Beijing. Table 1 shows consumption. On the other hand, indoor air quality has caught attention of the public in China. Volatile organic compounds (VOCs) and carbonyl compounds are a group of major indoor air pollutants that has been associated with many health effects including cancer (WHO1987). It is suspected that VOCs and carbonyl compounds are the major factor for “sick building syndrome” (SBS) (Molhave et al. 1986). In order to estimate the future trend of the residential energy consumption and indoor environment in China, it is necessary to understand the situation of the usage of facilities, the indoor thermal conditions and air quality. *Contact Author: Hiroshi Yoshino, Graduate School of Engineering, Tohoku University, Aoba 06, Sendai 980-8579, Japan Tel:+81-22-217-7883, Fax:+81-22-217-7886 E-mail:yoshino@sabine.pln.archi.tohoku.ac.jp Fig.1. Location of Beijing and (Received November 8, 2003 ; accepted April 6, 2004) the cities for measurement. Journal of Asian Architecture and Building Engineering/May 2004/54 47 the summary of this survey. Figure 1 shows the location The passive sampler suspended on breast for measuring of Beijing and the cities for measurement. Figure 2 personal exposure is shown in Fig.3. The passive gas shows the climograph [3] of cities where we have tubes (8015-066, Shibata Scientific Technology Ltd, investigated. For the climate in August, Beijing is very Japan) for VOCs and the 2, 4-dinitrophenylhydrazine hot and humid. (DNPH) cartridges (Xpsoure, Waters Ltd, USA) for carbonyl compounds were used in this study. These 2. Outline of Survey samplers for the indoor measurement were put in the 2.1 Questionnaire and Temperature Measurement living room. The samplers for the personal exposure In this study, an identical questionnaire and two liquid were fixed at the breast of household. The samplers for crystal thermometers [4] were distributed to the families the outdoor measurement were fixed inside an aluminum or relatives of teacher, the old boys of local university. flexible duct for protecting against solar and sky This method is the same as the previous investigation radiation. used [2]. The contents of the questionnaire are classified All these measurements were done in five consecutive into six key elements and tabulated in Table 2. Each days during the investigation period. family was requested to fix two liquid crystal thermometers onto the wall at a height of 1.1m above the floor in the bedroom and living room of their houses. The measurement was carried out in three different sections of five consecutive days from 6a.m.-8a.m. (morning), 11a.m.-1p.m. (mid-day) and 7p.m.-9p.m. (evening). The family was required to record the temperature readings from the liquid crystal thermometer within the interval of each of the section. The questionnaire was also completed by the family. 2.2 Measurement Detail In Beijing, several families within the distributed families were selected for further measurement. In this further measurement, three small data loggers with sensor were used to record the measurements of temperature and humidity for indoor and outdoor. Each sensor for the indoor measurement was mounted on supports at a height of 1.1m from the floor level in living room and bedroom. The sensor for the outdoor measurement was fixed inside an aluminum flexible duct in order to prevent solar and sky radiation. Regarding the measurement of air quality, passive sampling was applied in order to investigate the indoor Fig.2. Comparison of the climographs air concentration, the outdoor air concentration and the of major cities in China. personal exposure of VOCs and carbonyl compounds. Table 1. Summary of This Survey Table 2. Contents of The Questionnaire Survey 48 JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 3. Results of Questionnaire Survey 3.1 Characteristics of Buildings Figure 4 shows the floor areas of apartment unit in 2 2 Beijing. The floor areas range from 40 m to 140 m , with average area of 99.8 m . Figure 5 shows the height of building, in terms of number of stories in Beijing. Most buildings have the number of stories from 15 to 20, with average stories of Figure 6 shows the energy source for hot-water supply of apartment unit in Beijing. About 70% of the families use the town gas from natural gas, and 15% of the Fig.6. Energy for hot-water supply. families use electricity for hot-water supply. 3.2 Lifestyle Annual income is shown in figure 7. The number of effective replies is 49, that is 54% of collections. Many Fig.7. Annual income. Fig.3. Passive sampler suspended on breast for measuring personal exposure. Fig.8. At home ratio on weekdays and weekends. Fig.4. Floor areas of apartment unit. Fig.9. The relationship between occupantsí clothing and indoor Fig.5. Number of building stories. temperature in the evening. JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 49 residence replies forty thousand to sixty thousand. conditioners are not used at about 36% of the families Figure 8 reveals that 70-82% of residents in Beijing for a typical summer day. On the other hands, 61% of remain at home during the weekday from 8 a.m. to 5 the families use the air-conditioners. p.m.. During lunch hour from noon to 1 p.m., 82% of (3) Period of using air-conditioning the members of family stayed at their residences because Among the five cities, the period of using air- many residents prefer to return home for lunch. On the conditioning in Beijing and Xi’an are the shortest, as other hands, more than 90% of the residents remain at shown in Fig. 13. Based on the 50% line in Fig. 13, the home during weekend. period of air-conditioning used in Beijing is 2 months, The clothing worn by the occupants, male and female, and shorter than in Hong Kong, Shanghai and Changsha. in the evening is shown in Fig. 9, in terms of thermal From this survey, it is found that the adoption of air- resistance of clothing (clo) that was calculated by the conditioning in the cities except Hong Kong commences questionnaire for clothing. The average clo values for in the same months, however, the ending time of using male and female are 0.24 and 0.32 respectively. The clo values of male are lower than the female. 3.3 Air-conditioning and Its Usage [2] (1) Possession ratio of air-conditioner A comparison of the possession ratio of air-conditioner is given in Fig. 10 which includes the result in Beijing and other cities. About 80% of the families in Beijing have equipped air conditioners in both living room and bedroom, and most of them are split unit type. The type of air-conditioner equipped is shown in Fig.11. In Shanghai, investigation has been dane in 1998. But, it is reported by Long et al. [5] that the saturation level of air-conditioner in 2002 is 96.8%. (2) Cooling method Figure 12 shows the ratio of cooling method. The air- Fig.12. Ratio of cooling method. Fig.10. Ratio of air-conditioner equipped Fig.13. The period of using air-conditioning. in Families. Fig.14. Ratio of air-conditioner used in Families for a typical Fig.11.Type of air-conditioner equipped. summer day. 50 JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino air-conditioning in Beijing and Xi’an finishes half a the temperatures are betweenFig.19. The relationship month or a month earlier than in Changsha and Shanghai. between indoor and outdoor temperatures for This is due to the difference of the geographic location measurement period.Fig.20. The comfort zone of where Beijing and Xi’an belong to the cold region in ASHRAE in summer and indoor thermal China. environment.Fig.18. Results of the change of (4) Ratio of air-conditioning used for a typical temperature and humidity for an apartment. 21.5 C - summer day 30 C, and the changes are small in comparison to the Figure 14 shows the rate of air-conditioning used in outside temperature. From daytime to the evening, the five cities for a typical summer day. In comparison with Beijing, Xi’an, Changsha and Shanghai along, two peaks are seen in these cities during the daytime from noon to 3 p.m. of 50-70% and in the evening from 5 p.m. to 11 p.m. of 70-90%. Although the indoor temperature during the daytime is higher than in the evening, the usage of air conditioning is low. This is due to the fact that fewer residents stay at home during such time of the day. On the other hand, in the situation of Hong Kong the usage peak of air-conditioning is found throughout the night until morning. In comparison with the cities except Hong Kong, the lowest usage rate obtained in Hong Kong at 11 a.m. is lower than those observed in Beijing, Xi’an, Changsha and Shanghai at Fig.15. Operating time of air-conditioner. the same time on the day. (5) Operating time Figure 15 shows the operating time of air-conditioner per a day in Beijing. Some houses do not use air- conditioner on one hand and some houses use nearly 20 hours. The average of operating time is 9.8 hours. (6) Predetermined temperature Figure 16 shows the predetermined temperature of air- conditioner in Beijing. The predetermined temperature o o o ranges from 20 C to 30 C, with average area of 25.2 C. 3.4 Results of Indoor Temperature Measurement by Liquid Crystal Thermometer Figure 17 shows the average values and standard deviations of the temperatures in the living room, bedroom and outdoor of residents in the five cities of China in the evening. The temperatures of the living Fig.16. Predetermined temperature room in Beijing are almost the same as the bedroom, of air-conditioner. and the average is about 27 C, which is also higher than the outdoor. The situation of the indoor temperatures in Beijing is the similar to Xi’an. The temperatures of the living room in Shanghai are the highest in the five cities. 4. Results of Field Measurement 4.1 Indoor Temperature and Humidity Measurements were taken in 5 consecutive days in Beijing from August 21 (0:00 hour) to August 25 (24:00 hour) in 2002. Less families use air-conditioning during the measurement period in Beijing. However, some families are found using air-conditioning for a few hours during the measurement period. House-A is one of such houses and the result of the measurements at House-A is shown in Figure 18. House-A was built after 2000, and its outer wall is made of reinforced concrete with internal insulation of 50mm. Air-conditioners are set in the living Fig.17. Average values and standard deviations in the living room, bedroom and outdoor. room and bedroom. In both living room and bedroom, JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 51 indoor temperatures are lower than the outdoor periods. The variations of indoor relative humidity are temperature. This family uses the air-conditioners in within the range of 38%RH - 80%RH in both rooms. living room during the evening but in the bedroom during The indoor absolute humidity shows almost the same the sleeping hours. Therefore, the temperature, relative value as the outdoor except the operating time of air- humidity and absolute humidity are lower during these conditioner, and the difference is within the range of Fig.18. Results of the change of temperature and humidity for an apartment. Fig.19. The relationship between indoor and outdoor temperatures for measurement period. Fig.20. The comfort zone of ASHRAE in summer and indoor thermal environment. 52 JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 7g/kg’ - 18.7g/kg’. China. All of the personal exposures of formaldehyde 4.2 Relationship Between Outdoor and Indoor are higher than 80 mg/m . Figure 22 shows that the Temperatures [2] indoor toluene concentration is approximately between 3 3 Figure 19 shows the relationship between indoor and 25 mg/m and 405 mg/m . The other compounds are outdoor temperatures in the five cities during the shown in Table 3. The source of formaldehyde and VOCs measurement period. The sleeping hours, daytime and are expected to be indoor because of indoor evening are specified as 0:00-4:00, 12:00-16:00 and concentration/outdoor concentration ratios (I/O) are 18:00-22:00, respectively. Each plot means an average larger than 1. Most of indoor concentration/personal value during each period of each day. exposure ratios (I/P) are about 1. The concentrations of In Beijing, the temperature in living rooms is lower these chemical compounds were relatively higher in than the outdoor temperature during daytime. However, newly constructed houses. it becomes the same in the evening as outside temperature. In bedrooms, the temperature during sleeping time is higher than the outdoor temperature, except a few families that used the air-conditioners. 4.3 Evaluation of the Indoor Thermal Environment Based on Comfort Index [2] Figure 20 shows the comfort zone of ASHRAE [6] in summer and indoor thermal environment. Indoor temperature and humidity are in the ranges of 26 C - 30 C and 50%RH - 70%RH at daytime, night time and sleeping time. The indoor thermal condition of these three periods in the case of Beijing is outside the ASHRAE comfort zone. However, ASHRAE comfort zone is used under the situation that summer clothing is Fig.21. Formaldehyde concentration. light slacks and a short-sleeved shirt or a comparable ensemble with an insulation value of 0.5 clo for air movements less than 0.25 m/s. The temperature boundaries of the comfort zone can be shifted -0.6 C per 0.1 clo for clothing levels other than 0.5. o o Accordingly, it can be shifted to 1 C - 2 C high temperature side, considering clothing levels, and the thermal condition of a few families can be included in the comfort zone. Many occupants evaluated that indoor thermal environment in summer was ‘neutral or slightly hot’ during daytime and night. 4.4 Indoor Air Quality Figure 21 reveals that the indoor formaldehyde 3 3 concentration is between 14 mg/m and 898 mg/m . Formaldehyde concentration in four houses exceeds the Fig.22. Toluene concentration. standard, set as 80 mg/m by the National Standard of Table 3-1. Organic Compound concentration. JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino 53 Table 3-2. Organic Compound concentration. contract No. 13574007. The authors would like to thank 5. Conclusions Prof. Rongyi Zhao (Dept. of Building Science School Questionnaire investigation for the indoor living of Architecture, Tsinghua University) and the old boys conditions together with field measurement were carried of Tsinghua University, Tongji University and Tohoku out to the urban residents (family type) of Beijing in the University for their great cooperation during the summer of 2002. Based on the results from this study, investigation. The authors also express their thanks to the conclusions are drawn as follows: Miss. Haihong Lou (Atmax Co. Ltd.) for providing her 1) Air conditioner type used in Beijing is mostly the split- data results and her advises. unit type. About 80% of the households in Beijing have air conditioners equipped in living room and References 1) Hiroshi Yoshino and Haihong Lou (2002), Indoor Thermal bedroom. Environment of Residential Buildings in Three Cities of China, 2) The air-conditioning operation period is from June to Journal of Asian Architecture and Building Engineering, Vol. 1, September. During the day, the peak period in No. 1, 129-136. operating the air-conditioning is in the daytime and 2) Hiroshi Yoshino, Shan Guan, Yu Fat Lun, Takayuki Shigeno, evening. Yasuko Yoshino and Qingyuan Zhang (2002), Summer Survey on Indoor Thermal Environment of Urban Residential Buildings in 3) Indoor temperature and humidity are in the ranges of China, Journal of Asian Architecture and Building Engineering, 26-30 C and 50-70 %RH at daytime, night time and Vol. 1, No. 2, 65-72. sleeping time. Many occupants evaluated that indoor 3) National Astronomical Observatory (ed.) (2001) Rika nenpyo thermal environment in summer was ‘neutral or (Chronological Scientific Tables), Maruzen Co., Ltd., Vol. 74 (In slightly hot’ at daytime and night. Japanese). 4) Yoshino H., Hasegawa F., Sawada K., Ishikawa Y., Akabayashi S., 4) Formaldehyde concentration in four houses exceeds Kikuta M. (1984), Analysis on regional characteristics of winter the criterion, set as 80 mg/m by the National Standard thermal performance and occupants' behavior of detached houses of China. in Tohoku city area, Transaction of the Architectural Institute of Japan, No. 345, 92-102 (In Japanese). 5) Weiding Long, Ting Zhong and Beihong Zhang (2003), Acknowledgements SITUATION AND TRENDS OF RESIDENTIAL BUILDINGS This study is supported by The Ministry of Education, ENVIRONMENT SERVICES IN SHANGHAI, Proceedings of The Culture, Sports, Science and Technology under the th 4 international Symposium on HVAC, Beijing, China, 493-498. 6) ASHRAE HANDBOOK, FUNDAMENTALS (2001). 54 JAABE vol.3 no.1 May. 2004 Hiroshi Yoshino

Journal

Journal of Asian Architecture and Building Engineering – Taylor & Francis

Published: May 1, 2004

Keywords: China; indoor environment; residential building; questionnaire investigation; field measurement

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