The Effects of Orientations on the Room's Thermal Performance in the Tropics Leng Pau Chung 1, a , Mohd Hamdan Ahmad 2,b Dilshan Remaz Ossen 1,c Malsiah Binti Hamid 1,d Mohammad Baharvand 1,e 1 Department of Architecture, Faculty of Built Environment, Universiti Teknologi Malaysia, Johor Bahru, Johor Malaysia 2 Institute Sultan Iskandar of Urban Habitat and Highrise, Level 4, Dewan Sultan Iskandar, Universiti Teknologi Malaysia, Johor Bahru, Johor Malaysia a pcleng2@live.utm.my , b b-hamdan@utm.my , c b-dilshan@utm.my , d malsiah@utm.my, e baharvand12@gmail.com Keywords: orientation, natural ventilation, thermal performance, windows Abstract. Thermal performance of terrace house in Malaysia very much depends on the spatial design due to limited responsive environment factors. Building orientation is one of the important responsive factors under design consideration. The main concerns of the opening’s orientation are solar radiation and wind. In Malaysia, the maximum amount of solar radiation directly affects the thermal performance and thus the orientation of the window should be designed in the way to minimize solar gain and maximize natural ventilation. This paper investigates the effect of building orientation on the thermal performance of the residential room with solar chimney. The case study house facing north was located at Kuching, Sarawak, Malaysia. The field measurement was conducted in the case study house compound on 16 may 2012 to obtain the boundaries condition for CFD (Computational Fluid Dynamic) simulation. Four cardinal orientations were selected to investigate the thermal performance via CFD in DesignBuilder. The results show that the south facing window could maintain the lowest air temperature in the indoor environment with mean air temperature of 31.78°C and air mean velocity 0.023m/s with 35°C extreme outdoor temperature and zero wind velocity. Introduction. Sustainability becomes the trend of the building industry development over the concerns of global warming in recent years. As one of the main contributors of the carbon footprint in global context, building industry has the great responsibility to reduce the emission of the greenhouse gases [1]. In Malaysia, housing considered as the major contributor of carbon emission and energy user, which contribute 30% of the total due to the critical dependents of mechanical ventilation system [2] Thus, rethinking the design for the sustainable residential building with natural ventilation system is critically important in order to ensure the sustainability no longer a myth. There are dozens of way to go sustainability; however, the best way to achieve sustainability in housing design is adapting the passive architecture development concept as strategies to improve the indoor thermal environment and reducing the dependents on mechanical cooling system [3].The orientation of building is a significant consideration in early design process for architects. Thus, in this paper the effects of four cardinal orientations on the thermal performance of the residential room in single storey terrace house that attached with solar chimney were investigated. Hot and humid climate in Malaysia considered as the most challenges climate to moderate or handle through architecture design, due to its long hour and high intensity solar radiation throughout day time, the heavily rains and prevailing winds caused by Monsoon seasons [4]. The terminology of “passive architecture” can be defined as the ‘ecological building’, ‘green building’, and ‘energy efficient’ building that shield the occupants from local climate elements which form the protective skin that create thermal comfort to occupants. Thus, from the definition of the passive architecture, other than huge roof that could protect occupants from direct solar radiation, the orientation of the Applied Mechanics and Materials Vol. 567 (2014) pp 631-636 Online available since 2014/Jun/06 at www.scientific.net © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.567.631 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 161.139.220.131, Universiti Teknologi Malaysia UTM, Johor Bahru, Johor, Malaysia-10/07/14,08:08:29)