The role of structure cooling to reduce the effect of urban heat island in Mumbai

摘要

In India, for centuries, structure cooling principles have been part of strong architectural heritage. Buildings like Taj Mahal, Gol Gumbaz and temples of Hampi are a few notable examples of naturally cooled buildings. Some have used thermal mass, some have used water, while others use the combination of both to provide thermal comfort in the building as well as outside the building. Anthropogenic activities in urban areas increase usage of devices like air conditioning for human comfort inside a building. Typically, these principles discourage any external and/or induced forms of cooling. Less use of artificial systems means less heat and emitting less greenhouse gases in the environment. In an illustrative experiment, structural cooling system is introduced in a commercial building in Mumbai (hot and humid climate) to reduce the cooling load of the conventional air-conditioning system reducing overall heat load. An air-conditioning system typically adds ~30% more heat from the compressors. This increases the ambient temperature of the area. In dense urban environments, this process escalates till a heat island is formed [Oke, T. (1982). The energetic basis of the urban heat island. Journal of the Royal Meteorological Society, 708(455), 1-24; Weng, Q., Dengsheng, L, & Schubring, J. (2004). Estimation of land surface temperature-vegetation abundance relationship for urban heat island studies. Remote Sensing of Environment, 89, 467-483]. A combination of structure cooling and an air conditioner can be used to significantly reduce load on the air conditioners. It will drastically reduce the energy consumption and resultantly the pollution in the environment. In Mumbai, India's largest city, the ambient temperatures are sometimes 40-45°C in peak summers. To reduce the cooling load of the air-conditioning system, the structural cooling system was introduced as an innovative technique to reduce heat inside the structure and also in the environment. Application of such technique will be very useful on the structures like airport, station areas and commercial complexes to reduce the heat and pollution in the environment.