Thermal performance characteristics of unshaded courtyards in hot and humid climates Amirhosein Ghaffarianhoseini a , Umberto Berardi b, * , Ali Ghaffarianhoseini c a Department of Geography, Faculty of Arts and Social Science, University of Malaya (UM), Kuala Lumpur, Malaysia b Department of Architectural Science, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada c School of Engineering, Faculty of Design and Creative Technologies, AUT University, Auckland, New Zealand article info Article history: Received 10 November 2014 Received in revised form 17 January 2015 Accepted 1 February 2015 Available online 7 February 2015 Keywords: Outdoor thermal comfort Urban microclimate Hot and humid climate Courtyard Urban design abstract In recent years, there has been a growing interest in the design of courtyards for the microclimatic enhancement of outdoor spaces. However, there is still little knowledge regarding the thermal perfor- mance characteristics of courtyards, particularly in hot and humid climates. This study evaluates the ability of unshaded courtyards for providing thermally comfortable outdoor spaces according to different design configurations and scenarios, including the orientations, height and albedo of wall enclosure, and use of vegetation. The software ENVI-met was used as a tool for simulating the thermal performance of courtyards in the hot and humid climate of Kuala Lumpur, Malaysia. The PMV and the number of hours per day that a courtyard could be enjoyed once the proposed design suggestions were implemented are assessed. Likewise, the Physiologically Equivalent Temperature (PET) index allowed to further explore the thermal comfort conditions of courtyards. As a result, guidelines are proposed in order to optimize the design of courtyards towards enhancing their thermal performance characteristics. In particular, the study shows that according to design parameters such as the building height ratio, an abundance in the amount vegetation the courtyard can achieve an acceptable level of thermal comfort for the tropics and may be enjoyed by its users for a long duration of daytime even during the noontime. Finally, this paper stresses that only well designed courtyards may represent a valid option for sustainable built environments. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Modeling the relationship between buildings and the sur- rounding outdoor environment is a multidisciplinary imperative for urban climate and outdoor thermal comfort [1e3]. In view of the negative impacts of the urban heat island effect, particularly on energy use, air quality and human health [4] and its significant influence on urban comfort [5], meteorological studies which previously focused primarily on the meso-scale (10e40 km) have recently started to focus on the micro-scale (less than 1 km). This is due to the importance of the microclimate of outdoor spaces and urban canopy layers as significant elements of contemporary urban areas [3e5]. Given the growing interest in outdoor thermal comfort and urban life [6], various attempts have been made to study the im- pacts of courtyards on natural ventilation and thermal comfort [7e9]. In fact, several potential benefits can be achieved by con- trolling the micro-scale characteristics of outdoor spaces through courtyards. The impact of courtyards in some climates has been assessed qualitatively and quantitatively by using field measurements and computer modeling [1,10e14] However, there have been very few studies [2,15,16] that focus on the tropical climate where, due to high temperatures and relative humidity levels, the utilization of courtyards merits detailed investigations. In the context of the tropical climate, cooling effects in outdoor spaces can be enhanced by reducing the solar radiation received by the ground [17]. This study aims to evaluate quantitatively the thermal effects of a courtyard in Malaysia and to suggest guidelines to design more sustainable built environments in this climate zone. 2. Thermal effects of courtyards A courtyard is an enclosed outdoor or semi-outdoor space sur- rounded by buildings and open to the sky. Courtyards were pri- marily adopted in vernacular buildings in parts of Asia, the Middle * Corresponding author. Tel.: þ1 416 979 5000x3263; fax: þ1 416 979 5153. E-mail address: uberardi@ryerson.ca (U. Berardi). Contents lists available at ScienceDirect Building and Environment journal homepage: www.elsevier.com/locate/buildenv http://dx.doi.org/10.1016/j.buildenv.2015.02.001 0360-1323/© 2015 Elsevier Ltd. All rights reserved. Building and Environment 87 (2015) 154e168