How do green roofs affect per capita energy consumption in residential buildings under various climate conditions?

Abstract

Green roofs are innovative techniques for creating a low-cost, sustainable environment that have been demonstrated to save energy in buildings and reduce ambient temperatures. In general, the internal temperature of a building is determined by the energy used for lighting and electrical equipment, ventilation, heating caused by light entering the building through windows, convection through the walls, and convection through the roof. In hot seasons, green roofs reduce the need for cooling by lowering the temperature of the lower surfaces of the roof, thereby lowering the internal temperature of the structure; in cold seasons, they act as insulation by reducing heat loss via convective movement through the roof. Heating and cooling costs account for one-third of the energy used in modern buildings. Green roofs may be potential to reduce heating and cooling costs. This study was conducted to address the topic of green roofs with little emphasis on roof structures and their role in maximizing energy efficiency. A one-story residential building in two non-insulated and insulated states and three climatic zones was used for dynamic simulation. The hot and humid climates of Medan, Indonesia, Najaf, Iraq, and Moscow, Russia were studied. Green roofs reduce cooling loads in hot, humid environments. Green roofs can reduce a building's energy use by 30.7% because cooling loads are the most common in this region. Increased thermal resistance reduces heating load by up to 71%. Due to the heavy cooling load in these regions, a green roof is used to save energy. Dry weather condition appears to reduce green roof performance compare to humid climate.