Effect of building envelope on thermal environmental conditions of a naturally ventilated building block in tropical climate

This article presents the effect of envelope measures on thermal environmental conditions of a naturally ventilated building block in composite climate of India. Envelope measures such as roof U-value, wall U-value, glass U-value and glass solar heat gain coefficient, roof reflectance and two combinations of these measures (total seven cases) are analysed as recommended by National Energy Conservation Building Code-India (ECBC) through prescriptive route. Subject building is modelled and simulated using dynamic thermal simulation tool. Two approaches of thermal comfort have been used in this study such as heat balance model based on laboratory study and adaptive model of thermal comfort based on field findings. Thermal environmental conditions are evaluated based on operative temperature with and without considering the effect of thermal adaptation. This study found that comfortable temperature varies from 20.3celcius to 31.5celcius based on calculation of comfortable temperature through comfort temperature equation during winter to summer season in warm climatic conditions. This study concludes that envelope with ECBC specifications offer 60% hours under comfort state which were not comfortable with conventional practiced envelope specifications of India. The same methodology is also used to investigate the effect of ECBC envelope specifications in other climatic conditions such as hot and dry, and warm and humid climate of India. Practical applications: The thermal performance of building envelope varies from climate to climate therefore care should be taken to choose particular envelope measure. This study aims to improve comfort conditions in naturally ventilated building block considering building code with/without thermal adaptation. This research would be helpful to architects, engineers and building constructors to choose the most effective or climate responsive envelope option for better thermal environment quality of the proposed building design. Use of thermal simulation tool is also recommended to examine the effect of envelope options on thermal comfort.