EVALUATING THE PASSIVE DESIGN STRATEGIES FOR INDOOR THERMAL COMFORT IN WARM HUMID CLIMATE-CONTEXTUAL STUDY OF TRIVANDRUM, KERALA

Abstract

Kerala located at the southernmost tip of the Indian subcontinent, guarded by Arabian Sea and Western Ghats has unique climatic and architectural characteristics compared to the rest of India. With two predominant seasons i.e. rainy and non - rainy and 120 to 140 heavy rainy days per year, the region experiences a warm humid climate. Fluctuations in mean temperature are less whereas humidity shows greater fluctuations. Vernacular architecture of different regions across the world has successfully employed natural energy resources and sinks to achieve thermal comfort inside built structures. Traditional architecture of Kerala evolved with strong inclination to Climatological aspects and vernacular resources is highly significant in this regard!'Vastu Shastra", the science of buildings followed in the region ensured proper air movement and adequate ventilation inside the built forms, which can be considered as the basic requirements of any thermal efficient building located in a warm humid zone. The use of vernacular resources for construction makes the architectural typology distinctly energy efficient and sustainable. From the user responses as well as quantitative evaluations it is clear that the traditional built forms of the area are far superior in terms of thermal efficiency. The change in social settings i.e. from matrilineal joint families to nuclear families, increased cost of construction, lack of availability of materials and skilled labour etc can be attributed as reasons for the difficulties in reproducing the traditional architectural forms as such. After 1940's typical contemporary houses as seen today, built with high specific heat materials like concrete, attained dominance in the region. Contemporary architecture is influenced by rapid industrialization and witnesses thermally inefficiency and a shift towards mechanical devices for comfort. This is mainly due to the wilful ignorance of the society regarding the innumerous efficient strategies and intelligent systems used in the region since decades to achieve indoor comfort. But parallel to this there are some attempts by a few concerned architects to create thermally comfortable naturally ventilated houses in a contemporary scenario. Laurie Baker was one of the pioneers who developed cost efficient strategies for indoor thermal efficiency in a contemporary framework. His firm Costford, the Nirmithi Kendra of state government and many other eminent architects and construction activists of the region are in the process of research on the efficiency of different passive strategies with respect to the climate of the Indoor Thermal Comfort 1 2013 region. But still the percentage of houses built without any concern for achieving thermal comfort is very high. The study aims to identify and analyze the various strategies for indoor thermal comfort in domestic structures for a warm humid climatic context and to conduct case studies of successful models in this regard. Based on the literature study, case studies as well as computer based simulation modelling the various strategies and factors contributing to thermal comfort in residential structures of the region are to be analyzed. The whole residential system is divided into wall systems, roof systems and daylighting and ventilation systems and in each case possible alternatives with their thermal efficiency potential are quantified. Inferences are derived from the study and based on that the conclusions as well as recommendations are framed.