In-Situ Studies on the Effect of Solar Control Glazings on In-Cabin Thermal Environment in 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 in-cabin 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 is 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 is simulated for a vehicle running speed of 45 kmph. 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 in terms of temperatures for comparison of various glazing sets. Reductions in heat loads are compared with experimental data of non-absorbing and reflective glazing sets available in literature. Best suitable combinations for front and back windshields, front and back side doors for the chosen vehicle are discussed in view of total solar energy transmission through the glazings and occupants thermal comfort.