Traditional Malay house has characteristics of the passive thermal design that naturally practices climatic design strategies. Currently, Urban Heat Island (UHI), causing an increase in energy consumption for cooling purposes, especially in the residential sectors. Consequently, modern building construction has a poor passive thermal design. This study aims to assess the thermal performance of Negeri Sembilan traditional Malay house towards sustainable practice in the tropical environment. The main finding shows that house openings allow natural cross-ventilation, while less strategic house orientation towards climate factors and lightweight materials used contributes to the uncomfortable of the interior spaces reaches as much as 35ºC during the peak time of the day. This study highlights ideas and knowledge in improving the construction technology for modern architecture to produce an effective indoor thermal performance in a tropical environment.