Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 121 (2015) 1721 – 1725
9th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC) and the 3rd International Conference on Building Energy and Environment (COBEE)
Typical Dressing Behavior and Subjective Temperature in BeijingTianjin Summer Air-conditioning Office Building Sha Lia,*, Xiaoming Qianb, Ruiliang Yanga , Yu Chena, Jiaqi Yanga a
School of Mechanical Engineering,Tianjin Polytechnic University, Tianjin,China b School of Textile Engineering,Tianjin Polytechnic University, Tianjin,China
Abstract By using field questionnaire and sweating manikin in laboratory, this research finds that in Beijing-Tianjin office building, summer air-conditioning typical clothing is short sleeves and long pants, the major material of the fabric is pure cotton. The average clothing insulation is 0.37 clo, The average moisture vapour resistance is 18.09 m2Pa/W. Compared with thermal resistance of standard clothing as set by national comfort standard, typical clothing thermal resistance is 0.13 clo lower, and corresponding subjective temperature is 0.81ć higher. So, indoor air-conditioning design temperature can be made a little bit higher than current recommended value. Subjective temperature formula in such area is amended and used for reference for office building energy conservation design and operation. © 2015 2015Published The Authors. Published by isElsevier © by Elsevier Ltd. This an open Ltd. access article under the CC BY-NC-ND license Peer-review under responsibility of the organizing committee of ISHVACCOBEE 2015. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ISHVAC-COBEE 2015
Keywords: Typical dressing behavior; clothing insulation; moisture vapour resistance; thermal comfort; subjective temperature
1. Introduction Office building is mainly used for work, and its indoor environment may directly influence staff’s physical health and work efficiency[1] . And staff’s clothing is a significant factor to assess their thermal comfort. Summer airconditioning room temperature scale as set by current international standard and state standard applies for person feeling comfortable under standard thermal resistance of clothing (0.5 clo), and here thermal resistance of clothing is
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1877-7058 © 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ISHVAC-COBEE 2015
doi:10.1016/j.proeng.2015.09.141
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closely related with local habits and climates, so there is under the necessity of considering them when determining acceptable temperature scale [2] . We have different traditional cultures, fashion and hobbies, living habits in various regions. Lots of textile are in good thermal conductivity, moisture permeability, and comfort character, and also have lower thermal resistance and moisture resistance than traditional textile[3]. Difference with description of clothing style in foreign literature, there is possibility of assessing thermal comfort inaccurately. Therefore, based on local climate, culture, economy, etc, determination of appropriate clothing comfort index could provide assistance for us to confirm kind of criteria on how to evaluate building indoor thermal or wet environment, and also to fulfill energy conservation if living in good and comfortable environment. Researches on links of clothing and comfort, done at home and abroad so far, find that mainly in European or hot region libraries or residences, different climates lead to different habits, different adaptability to climate, and different thermal resistance of clothing. Putting on or taking off clothes or change of thermal resistance can adjust thermal comfort, and that is an active method to maintain one’s conform[1] . Located in cold B zone, Beijing and Tianjin have cold climate in winter and hot weather in summer, thus their air-conditioning use days of more than 90ćЬd. Beijing-Tianjin various office buildings and comprehensive office building area rapidly increases and become main part of energy consuming. Staff working in office building has different clothings, which are determined by one’s gender, age, job, cultural background, life experience, aesthetic taste, etc. In order to study how clothing affects comfort, an field research is made in office buildings featured on concentrated air-conditionings in Beijing and Tianjin centre, and research includes individual background information, clothing style, material, comfort, etc, and testing of indoor environment thermal parameters as well. During the field research, those surveyed are in normal working condition, and that could provide an opportunity to accurately reflect relationship between person and environment. This research acquires a total of 532 effective questionnaires, in which 53% are from male staff, and remaining from female. Among these effective questionnaires, average height of staff is 168.6 cm, and average weight is 63.9 kg. Those surveyed are architects, teachers, bank officers, and the other three kinds; they all have lived in the region for over three years, and are well accustomed to Beijing and Tianjin cultural background and climates, etc.
2. Statistical analysis on clothing style and material Among these valid questionnaires, statistics of upper piece is shown in Fig.1. Short sleeves accounts for 83.1%, short sleeves + thin coat accounts for 7.5%, dress 7.1%, and others account for little. Therefore, typical upper piece is short sleeve in Beijing-Tianjin air-conditioning office building. Detailed material of upper piece is shown in Fig. 2. Pure cotton occupies the most, in amount of 75.7%, fiber and blending second most, separately occupy 10.9% and 8.1%, and remaining is the other materials. In case of only short sleeves, cotton occupies 78.3%. Hence, in Beijing-Tianjin summer air-conditioning office building, typical upper piece is made of pure cotton. long sleeve+thin coat 0.4%
short sleeve+thin coat 7.5%
long sleeve 1.9%
silk 1.7%
one-piece dress 7.1%
short sleeve 83.1%
long sleeve
short sleeve
long sleeve+thin coat
short sleeve+thin coat
blending 8.1%
wool 0.2% chemical fiber 10.9%
fibrilia 3.4% pure cotton 75.7%
one-piece dress
Fig. 1. Proportion of upper piece
pure cotton
fibrilia
silk
wool
chemical fiber
Fig. 2. Proportion of upper piece material
blending
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Among these effective questionnaires, lower piece proportion can be seen in Fig.3. We can find that long pants occupy 65%, short pants 20.7%, dress 12.8% and others occupy little. Therefore, typical lower piece is long pants in Beijing-Tianjin air-conditioning office building. Fig.4 describes material proportion of lower piece. Cotton accounts for most, in amount of 64.6%, others for little; provided research only on long pants, cotton occupies 66.5%. Hence, in Beijing-Tianjin summer air-conditioning office building, typical lower piece is made of cotton. kilt 12.8%
other 1.5%
chemical fiber 11.3%
blending 10.9%
other 2.3% pure cotton 64.6%
wool 3.4%
shorts 20.7%
silk 1.1%
long pants 65.0%
long pants
shorts
kilt
other
Fig. 3. Proportion of lower piece
fibrilia 6.4%
pure cotton
fibrilia
silk
wool
chemical fiber
blending
other
Fig. 4. Proportion of lower piece material
Based on link between local thermal sensation and whole thermal sensation, chest and belly, upper back and lower back, and also buttocks could lead majority whole thermal sensation, and yet shoes, socks have little influence on body thermal sensation[4]. So, this research only focuses on upper piece and lower piece, and concludes that in Beijing-Tianjin summer air-conditioning office building, typical clothing is short sleeves + long pants, and material for that is mainly made of pure cotton.
3. Thermal and moisture performance test for typical clothing Thermal performance of clothing is a key research for thermal comfort. Under the circumstance of air temperature controlled in traditional uncomfortable scope, within 26-30 ć , and PMV value controlled under 0.5,change of clothing material and air velocity could achieve better thermal comfort result[5] . Due to differences of real people and difficulties to accurately measure their heat or moisture dissipating capacity, there is no possibility of using real body to test clothing index. So heated manikin is often accepted to test clothing by many researchers[6]. Here we will use a sweating heated manikin provided by The Hong Kong Polytechnic University to test thermal and moisture performance parameters of typical clothing. According to requirements on measuring clothing thermal insulation and moisture vapour resistance by using a sweating heated manikin as set by GB/T 18398-2001, Standard test method for measuring the thermal insulation of clothing using a heated manikin, and ASTM F1291-2005, Standard test method for measuring the evaporative resistance of clothing using a sweating manikin[7,8,9]in School of Textile Engineering, Tianjin Polytechnic University , we take tests in a constant thermal, humidity laboratory, with indoor temperature of 20f1 ć, relative humidity of 55%+/-5%, air speed 0.2+/-0.1 m/s, and core temperature of heated manikin of 37f0.5 ć, thus maintaining its skin in constant condition of about 35ć [10]. Take naked test first to acquire manikin skin surface thermal resistance and moisture vapour resistance under still air layer; then take seminude test after wearing typical cotton long pants, proximate to testing average value; last take test after wearing typical long pants and common cotton short sleeves, thus finding clothing average thermal performance parameter, which can be seen in Table 1. After testing eight different clothing, we find that average thermal insulation is 0.0573 m2Ьć/W (0.37clo) and average moisture vapour resistance is 18.09m2Pa/W.
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Sha Li et al. / Procedia Engineering 121 (2015) 1721 – 1725 Table 1. Thermal performance parameter of summer typical clothing. No
Thermal
I
Material and color of short sleeves z1 z2 z3 z4 z5 z6 z7 z8
insulation t /(m 2 ·ć/W) 0.0591 0.0714 0.0459 0.0504 0.0526 0.0497 0.0614 0.0683 0.0573
1+1 rib, light camel Spinning denim, blue Jersey, red Mercerized cotton jersey, russet Figured cloth, black Jersey, light grey Small mesh fabric, camel grey Laplacian cloth, deep grey Average
4. Subjective temperature
Evaporative
R
Thermal/evaporative index
Im
resistance e /(m2 ·Pa/W) 11.1958 14.1672 21.6057 19.6676 16.7128 24.2128 18.7406 18.3823 18.0856
0.3201 0.3056 0.1288 0.1554 0.1907 0.1243 0.1984 0.2250 0.2060
of seated posture with typical clothing
Workers often sit in the office building, so we use relevant research results for reference to confirm thermal performance parameter of seated position with typical clothing, due to limitation of standing heated manikin. Based on international standard ISO9920, body thermal resistance at seated position has links with height and thickness of seatback. Generally speaking, office chair produces thermal resistance increment of about 0.0062-0.0264 m2Ьć/W (0.04-0.17clo) [11], so here we use its average value 0.0163 m2Ьć/W (0.105clo). Table 2 is test result on clothing thermal resistance at seated position with typical clothing and standard clothing used by international and domestic comfort standard. Table 2. Clothing thermal resistance at seated position with typical clothing and standard clothing(clo). Average value with typical clothing
Average value with standard clothing
Standing posture
Seated posture
Standing posture
Seated posture
0.37
0.475
0.5
0.605
Actual office building equips with HAVC, and its design and operation just involves physical environment, so environment variable and body variable should be considered in comfort equation. HAVC operates to offer relevant temperature that indoor body need, and that temperature is decided by body variable. Subjective temperature refers to temperature indoor people need, temperature that giving people predicted comfort based on specified rate of metabolism and thermal resistance of clothing. Formula[1]. found below shows relationship among body activity amount, clothing thermal resistance and subjective temperature, and subjective temperature can be determined upon calculating body variable, according to thermal resistance of typical clothing and standard clothing with seated posture as shown in Table 2.
tsub =33.5 3I t (0.08 0.05I t ) H
(1)
Where, It is clothing thermal resistance, H is body net heat quantity, H=M-W (M means Metabolic rate, and often values 70 W/m2 with seated position in office building; W is body caused mechanical work, W=η M (η means mechanical efficiency). Usually ¨ is not more than 10%[1] . for easier calculation. There is less likely to have still seated position all the time in the office, so here ¨ is 7.5%, and H=M-W=92.5%M. Then subjective temperature of typical clothing is 25.36ć, of standard clothing 24.55 ć, and both of them are lower than field tested air temperature, therefore such subjective temperature formula is not right for Beijing-Tianjin area. Because of the fact that thermal resistance of typical clothing is 0.13 clo lower than that of standard clothing, and that relevant subjective temperature of typical clothing is 0.81 ć higher than that of standard clothing, in Beijing-Tianjin office building, summer air-conditioning
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temperature can be made little bit higher than current recommended value. As sort of desired temperature, subjective temperature can be amended by actual calculated expectation temperature, and its amended formula (2) for such area is shown below after acquiring onsite statistics data:
tsub =33.5 0.6I t (0.08 0.05I t ) H
(2)
5. Conclusions 1. Field questionnaire survey shows that in Beijing-Tianjin office building, typical clothing under summer airconditioning is short sleeves + long pants, and they are made of pure cotton; 2. Test by using sweating heated manikin finds that for typical clothing, average thermal resistance is 0.37 clo, moisture vapour resistance is 18.09 m2•Pa/W, and that thermal resistance of typical clothing is 0.13 clo lower than that of standard clothing according to standard requirement on comfort, relevant subjective temperature of typical clothing is 0.81 ć higher than standard clothing, hence, indoor air-conditioning temperature could be made a little bit higher than current suggested value. 3. Beijing-Tianjin subjective temperature formula has been amended. References [1] B. Li, J. Zheng, R. Yao, The indoor thermal environment and thermal comfort of human body, 1st ed., Chongqing University press, Chongqing, 2012. [2] S. Jing, B. Li, N. Li, Synopsis of an international standard on thermal comfort based on thermal sensation criteria, J. Heating ventilating and air conditioning. 40 (2010) (8) 110-113. [3] G. Qiu, Y. Jiang , L. Liu, Study of new type fiber materials and the comfortability, J. knitting industry. 5 (2004) 55-58. [4] H. Zhang, Human thermal sensation and comfort in transient and non-uniform thermal environments, Ph.D. Thesis, University of California at Berkeley, Berkeley, 2003. [5] N. Ghaddar, K. Ghali, S. Chehaitly, Assessing thermal comfort of active people in transitional spaces in presence of air movement, J. Energy and Buildings. 43 (2011) 2832-2842. [6] W. Zhang, Clothing comfort and function, 2nd ed., China Textile Press, Beijing, 2011. [7] MOUHRD of the PRC, Standard GB/T 18398 – 2001, Testing method for clothing thermal resistance- Thermal manikin method, China Standard Press, Beijing, 2004. [8] ASTM, Standard F1291-2005ୈStandard test method for measuring the thermal insulation of clothing using a heated manikin, Pennsylvania, USA, 2005. [9] ASTM. Standard F2370-2005ୈStandard test method for measuring the evaporative resistance of clothing using a sweating manikin, Pennsylvania, USA, 2005. [10] X. Qian, J. Fan, Prediction of clothing thermal insulation and moisture vapour resistance of the clothed body walking in wind, J. Annals of Occupational Hygiene. 50 (2006) 833-842. [11] Y.S. Wu, Development of a sweating fabric manikin with sedentary and supine postures, Ph.D. Thesis, The Hong Kong Polytechnic University, Hong Kong, 2010.
