In-situ studies on the effect of solar control glazings on in-cabin thermal environment for hot and humid climatic zones

Thermal comfort in a passenger cabin is the basic necessity of an occupant especially in hot and humid climatic conditions. It is known that the reflective glazing solutions provide better thermal comfort inside the cabin due to significant reflection of IR part of solar radiation. However, in hot and humid climatic zones like India, significant reduction in heat load can also be achieved through cost effective solar control absorbing glazings. Thus, the present work aims to study the effect of solar control absorbing glazings on cabin inside temperatures and its impact on thermal comfort of the occupants in tropical climates. A combination of glazing sets with a range of solar energy transmission and absorption values are considered for the study. Indoor soak and cool tests are performed on a sedan model with multiple sets of solar control absorbing glass combinations. A constant ambient temperature of 38˚C and solar radiation of 1000W/m2 are maintained throughout the tests. Wind speed was simulated for a vehicle running speed of 45kmph. Net heat gain inside the cabin as a combination of various inward and outward loads of radiation through glazing is investigated. Accumulated heat is measured interms of temperatures for comparison of various glazing sets. Reduction of heat loads are compared with standard and reflective glazing sets from available measurements and literature. Best suitable combinations for front and back windshields, front and back rear doors for the chosen vehicle has been discussed with regards to total solar energy transmission through the glazings and occupant’s thermal comfort.