Thermal comfort conditions of shaded outdoor spaces in hot and humid climate of Malaysia Nastaran Makaremi * , Elias Salleh, Mohammad Zaky Jaafar, AmirHosein GhaffarianHoseini Department of Architecture, Faculty of Design and Architecture, University Putra Malaysia, Malaysia article info Article history: Received 23 December 2010 Received in revised form 19 July 2011 Accepted 21 July 2011 Keywords: Human thermal Comfort Outdoor spaces Hot and humid climate PET abstract In recent years, the accelerated rate of urban growth in tropical cities highlights the critical necessity of creating more outdoor spaces for leisure and recreation activities of citizens. Nevertheless, the thermal conditions and the thermal sensation of users have not been fully explored in outdoor environments of hot and humid climate. This fact elucidates the need for considering human thermal comfort in outdoor spaces with such climates. Consequently, in this research, a quantitative field study was applied to investigate outdoor thermal comfort conditions in hot and humid tropical climate of Malaysia. Thermal conditions of outdoor spaces were evaluated based upon the measurement of major climatic parameters, while the thermal perception of subjects was captured simultaneously using a questionnaire survey. The study concentrated on the shaded outdoor spaces within the campus of Universiti Putra Malaysia whereas the focus was on the students of university including local and international individuals as the respondents of inquiry. Meanwhile, the Physiologically Equivalent Temperature (PET) thermal comfort index was utilized to assess the thermal comfort conditions of selected areas. Results from this study indicated besides the substantial role of environmental factors, thermal adaptation and psychological parameters strongly affect human thermal comfort level in outdoor spaces. Moreover, this study represents that there is a significant difference between the responses of the local and the international subjects regarding the climatic conditions. The final outcome of the study contributes toward creating comfortable outdoor spaces in hot and humid contexts to enhance the quality of outdoor life in cities. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction The quality of outdoor spaces in urban areas plays a funda- mental role in quality of life within cities. Meanwhile, the rapid urbanization of the cities in recent years has increased the need for the creation of more outdoor environments for leisure and recre- ation activities of citizens [1,2]. Likewise, the condition of human comfort in outdoor spaces is vital to be considered during the design of outdoor spaces as it is affected by a wide range of parameters. Hence, creating thermally comfortable environments based on the climatic conditions is deemed to be as one of the substantial criteria during the design of outdoor spaces [3,4]. However, the studies with regard to understanding the outdoor climatic comfort conditions were mostly limited to temperate regions (e.g., [4,5,6]). Therefore, there is a significant lack of infor- mation on the thermal conditions and the importance of the role of human thermal comfort in relation with outdoor environmental quality in tropical regions [7,8,9,10]. This fact elucidates the need to investigate human comfort conditions of outdoor spaces within hot and humid climates based on the specific weather conditions along with the human parameters and the respective subjective responses. In regard with the evaluation of thermal comfort based upon the energy fluxes between body and environment, versatile thermal indices have been developed such as predicted mean vote (PMV) [11], effective temperature (ET*), standard effective temperature (SET*) [12], OUT_SET* [13,14] and physiologically equivalent temperature (PET) [15]. The PMV, ET*, and SET* indices have been designed for indoor use in accordance with the permanent envi- ronmental conditions of indoor spaces, whereas OUT_SET* and PET indices have been basically developed for calculation of the thermal comfort within outdoor environments [14]. Correspondingly, recent studies indicate that PET is the most suitable choices to assess thermal comfort conditions of outdoor environments rather than the indoor based thermal indices. The reason for aforemen- tioned fact is due to the consideration of the interrelation between human body energy balance and short- and long-wave radiation * Corresponding author. Tel.: þ60 172521617. E-mail address: Nastaran_makaremi@yahoo.com (N. Makaremi). Contents lists available at ScienceDirect Building and Environment journal homepage: www.elsevier.com/locate/buildenv 0360-1323/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2011.07.024 Building and Environment 48 (2011) 7e14