Green Roofs as Option to make Buildings , Communities and Cities and Carbon Neutral

Buildings use over 40% world’s total energy, 30% global raw material extracted, 25% timber harvested,16% fresh water withdrawal, 35% of world’s CO2 emission, 40% municipal solid waste generated and 50% ozone depleting CFC besides making 30% residents suffering from sick building syndrome. With large number of people rushing towards urban centres for living, working, healthcare, education, making livelihood and sourcing employment, energy requirements of cities, due to buildings, are going to rise sharply. As per McKinsey Global Institute Report (April, 2010), ‘India Urban Awakening: Building Inclusive Cities’, India needs to create, on annual basis, buildings to the tune of 700-900 million sqmts. Considering the large volume of built space to be created, implications of buildings in terms of resources, energy and waste, are going to be enormous. Thus buildings, as a sector, would require close scrutiny and monitoring, for effecting overall economy in the levels of energy consumption and for making cities resource efficient and sustainable. Within built environment building envelop, comprising of outer walls and roof of building, accounts for about two- third (60%)of total heat gain and heat loss within built space. Building envelop is known to be major determinant, dictating the urban sustainability besides operation and energy consumption pattern of the buildings. Accordingly, roofs and walls have to be planned, designed and constructed carefully and thoughtfully, for insulating buildings against gaining/losing undue heat and cold for making buildings sustainable, energy efficient and zero carbon. Green Roofs Green roof, as one the roof typology, is fast emerging as a preferred option for promoting sustainability in the buildings. Green roof, is defined as a space on the roof comprising of collection of greenery, planted on top of a man-made structure. Green roofs, as a solution to manage the temperature within the buildings and bringing nature into cities, have been part of the human history. The Hanging Gardens of Babylon, used an elaborate irrigation system to create terraced gardens while Europeans used traditional sod roofs for insulating houses (keeping the cold out during the cold winter months and keeping the heat in at the same time). Cities of today, are fast becoming spaces filled with buildings made of brick, mortar, glass, steel and concrete, eliminating nature and natural elements including green spaces, flora and fauna. Existing pattern of urban growth and development, has led to making cities both congested and warm, leading to rising temperature, global warming and large greenhouse gas emissions.