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

Buildings, by virtue of having large numerical value, providing space for human living and working besides being consumers of resources, energy and generators of waste play important and critical role in making human settlements, productive, efficient, livable and sustainable. No city can ever achieve sustainability, unless it is ably supported by qualitative and nature responsive passive built environment, which is carbon neutral and generator of minimum waste besides consuming minimum energy and natural resources. Buildings, by virtue of its fabric, structure, materials, structure,
material and construction technologies, are known to be largest consumers of energy, resources and generators of waste.

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.

Heat islands created in the urban areas, has led to sharp rise in demand and consumption of large fossil fuel-based energy, for keeping the buildings cool, warm and livable. Green roofs, offering variety of benefits in making buildings cool and bringing nature back, are fast returning to the cities. More and more urban buildings are opting for installing roof gardens,
making addition of rooftop planters and permitting the growth of vegetation. Germany, as a nation, has emerged as the global leader, with more than 14 percent of all roof area already made green.

Advantages- Green Roofs
Green roofs are known to be providers of numerous physical, social, economic and environmental benefits not only to the built environment, people and communities but also to the city, climate and human livability, in terms of ;

  • Reducing urban flooding ; reducing air pollution- Increasing oxygen production; improving air quality; purifying air; encouraging biodiversity, minimizing greenhouse gas emissions, removing air particulates; reducing carbon-footprints of buildings; improving property value and marketability; promoting economy, generating employment
  • Creating green elements; Improving aesthetics in building and neighbourhood;
  • Promoting qualitative living, working and promoting well-being of people through green environment; reducing stress; making people happy, heathy and more productive
  • Promoting utilization of unused roof space
  • Overcoming deficit of green spaces in the congested/core areas of city.
  • Making building operationally efficient and cost-effective; regulating the indoor temperature and reducing the ambient temperature; reducing energy costs ; providing natural insulation for buildings.; reducing/ lowering air- conditioning demand
  • Elongating the life of roof; providing natural protection against extreme heat –enabling green roofs to last– twice as long as traditional rooftops.
  • Making solar panel more efficiency; reducing the temperature on the roof; reducing energy costs.
  • Insulating buildings against noise- providing a quieter environment, both inside building.
  • Making buildings safe against fire by providing additional fire-resistant layer through plants with lot of moistures.

Way Forward

Green roofs offer enormous social , physical, economic and environmental advantages to the individuals, owners, communities, city , nation and planet earth, in terms of; making buildings cost-effective, energy efficient; consuming limited energy and resources; bringing nature into buildings/ city; reducing urban heat island; reducing the intensity of storm water and saving cities from flooding; reducing global warming and lowering carbon footprints of the buildings/city; conserving rainwater water; meeting deficiency of green spaces in congested parts of cities; making optimum use of available unused roof space without increasing the building footprints; promoting economy; generating employment; promoting socialization and security; making people happy, healthy and more productive; bringing birds back to the cities; growing vegetables and making cities self-sufficient in daily needs; eliminating transportation and refrigeration of vegetables; increasing value of properties; empowering cities to become zero-carbon.
Despite numerous benefits green roofs offer, major obstacles in promoting the green roof remains the non-availability of affordable and proven technologies and high initial cost. Green roofs typically cost two to three times more than a non-green roof. Although green roofs are not simple to construct or cheap to maintain, yet numerous benefits they offer in long term outweighs, the initial cost concerns. Over time, green roofs, pay for themselves besides making large contribution to the urban sustainability and urban environment. For creating awareness about the benefits and for promoting green roofs, cities need to launch pilot programs encouraging the installation of green roofs by offering financial and other benefits. However, reputed technical institutions like IITs/NITs needs to be roped in to promote research in evolving cost-effective and operationally efficient design of green roof, considering the different climate zones prevailing in India.

Green roofs should also be included as part of study curricula of all technical institutions to make students aware about the principles, concepts and technologies to be used in the planning, designing, construction and maintenance of green roof. Bye-laws applicable at the local level also need review and redefinition to facilitate the creation of green roofs in the city. Our capacity to promote the acceptability of green roof in the urban context, will hold the key to decarbonizing the cities and make them sustainable, livable and carbon-neutral.

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