Thermal comfort in naturally ventilated and air-conditioned buildings in humid subtropical climate zone in China

A thermal comfort field study has been carried out in five cities in the humid subtropical climate zone in China. The survey was performed in naturally ventilated and air-conditioned buildings during the summer season in 2006. There were 229 occupants from 111 buildings who participated in this study and 229 questionnaire responses were collected. Thermal acceptability assessment reveals that the indoor environment in naturally ventilated buildings could not meet the 80% acceptability criteria prescribed by ASHRAE Standard 55, and people tended to feel more comfortable in air-conditioned buildings with the air-conditioned occupants voting with higher acceptability (89%) than the naturally ventilated occupants (58%). The neutral temperatures in naturally ventilated and air-conditioned buildings were 28.3°C and 27.7°C, respectively. The range of accepted temperature in naturally ventilated buildings (25.0∼31.6°C) was wider than that in air-conditioned buildings (25.1∼30.3°C), which suggests that occupants in naturally ventilated buildings seemed to be more tolerant of higher temperatures. Preferred temperatures were 27.9°C and 27.3°C in naturally ventilated and air-conditioned buildings, respectively, both of which were 0.4°C cooler than neutral temperatures. This result suggests that people of hot climates may use words like “slightly cool” to describe their preferred thermal state. The relationship between draught sensation and indoor air velocity at different temperature ranges indicates that indoor air velocity had a significant influence over the occupants’ comfort sensation, and air velocities required by occupants increased with the increasing of operative temperatures. Thus, an effective way of natural ventilation which can create the preferred higher air movement is called for. Finally, the indoor set-point temperature of 26°C or even higher in air-conditioned buildings was confirmed as making people comfortable, which supports the regulation in China that in public and office buildings the set-point temperature of air-conditioning system should not be lower than 26°C.

[1]  J. F. Nicol,et al.  Understanding the adaptive approach to thermal comfort , 1998 .

[2]  Chungyoon Chun,et al.  Thermal comfort in Japanese schools , 2003 .

[3]  S. Sharples,et al.  A comparative analysis of short-term and long-term thermal comfort surveys in Iran , 2002 .

[4]  P. Fanger.  Moderate Thermal Environments Determination of the PMV and PPD Indices and Specification of the Conditions for Thermal Comfort , 1984 .

[5]  Z. Lian,et al.  Field study of a thermal environment and adaptive model in Shanghai. , 2006, Indoor air.

[6]  R. J. Dear,et al.  Thermal comfort in the humid tropics: Field experiments in air conditioned and naturally ventilated buildings in Singapore , 1991 .

[7]  A. P. Gagge,et al.  Standard Effective Temperature - A Single Temperature Index of Temperature Sensation and Thermal Discomfort , 1973 .

[8]  F. Nicol.  Adaptive thermal comfort standards in the hot–humid tropics , 2004 .

[9]  Chandra Sekhar,et al.  Thermal comfort evaluation of naturally ventilated public housing in Singapore , 2002 .

[10]  Gail Brager,et al.  Developing an adaptive model of thermal comfort and preference , 1998 .

[11]  N. Wong,et al.  Thermal comfort for naturally ventilated houses in Indonesia , 2004 .

[12]  Nyuk Hien Wong,et al.  Thermal comfort in classrooms in the tropics , 2003 .

[13]  Tri Harso Karyono,et al.  Report on thermal comfort and building energy studies in Jakarta—Indonesia , 2000 .

[14]  Demetrios J. Moschandreas,et al.  Thermal Comfort Investigation of Naturally Ventilated Classrooms in a Subtropical Region , 2007 .

[15]  P. Fanger,et al.  Upper limits for indoor air humidity to avoid uncomfortably humid skin , 1998 .

[16]  K. W. Mui,et al.  Adaptive comfort temperature model of air-conditioned building in Hong Kong , 2003 .

[17]  R. J. Dear,et al.  Thermal comfort in the humid tropics. Part I. Climate chamber experiments on temperature preferences in Singapore , 1991 .

[18]  Gail Brager,et al.  Thermal comfort in naturally ventilated buildings: revisions to ASHRAE Standard 55 , 2002 .

[19]  Wu Shao-hong.  On Subtropical Zone of China , 2006 .

[20]  R. Dedear,et al.  Validation of the predicted mean vote model of thermal comfort in six Australian field studies , 1985 .

[21]  M. Fountain,et al.  Laboratory studies of the effect of air movement on thermal comfort: a comparison and discussion of methods , 1991 .

[22]  J. F. Nicol,et al.  Thermal comfort: use of controls in naturally ventilated buildings , 2001 .

[23]  Ruey Lung Hwang,et al.  Field experiments on thermal comfort in campus classrooms in Taiwan , 2006 .

[24]  Ya Feng,et al.  Thermal design standards for energy efficiency of residential buildings in hot summer/cold winter zones , 2004 .

[25]  R. Dedear.  Developing an adaptive model of thermal comfort and preference , 1998 .