SUMMER PASSIVE COOLING POTENTIAL OF AN EXTENSIVE GREEN ROOF IN INDIAN COMPOSITE CLIMATE: A SIMULATION STUDY

Green roofs are a very important passive cooling technique which helps in reducing thermal heat gain and further reduction in temperature inside any habitable space. It relies on the thermal insulation of soil, shading by plant foliage and transpiration cooling, to reduce the indoor temperature. Green roof reduces the problem of solar roof heat gain with the help of plants. Simulations are essential tools for preliminary evaluations. It helps in foreseeing the effects of a certain technology, without physically constructing a model, which can be costly, and time taking. Green roof simulations help in predicting the outcomes of such installations without being built. The purpose of this study was to model, simulate, and compare the temperature reductions and relative humidity for a habitable room with extensive green roof, and a room without green roof, in a composite Indian climate. DesignBuilder software was used in this study. Two cases were considered for the modules, one with extensive green roof and the other with bare roof. Internal temperature and humidity data was gathered for both the cases. Simulations were performed for a period of one month i.e. from 12th May to 12th June (generally the hottest 30 days of the year), and hourly results were collected. The simulation results clearly highlight the amount of temperature reductions inside a habitable space, which is bringing the indoor environment close to the comfort range with respect to Indian context. This study hence shows that extensive green roofs are beneficial in providing better internal comfort during the summer months.