Green roofs for salubrious cities

The Environmental Planning and Coordination (EPCO) of Madhya Pradesh have taken an admirable initiative for promoting “green construction”. Quite obviously, the state is gradually becoming concerned about the urban environment and the progressive adverse impact on it of the burgeoning construction activity. Numerous multi-crore projects are either in progress or are on the anvil in major towns of the state. In Bhopal, for instance, one such project is already in progress. Clearly, the initiative is indicative of the government’s rising anxiety to forestall the environmental degradation that massive construction activity inevitably entails.

That large scale construction in urban areas causes a rise in ambient temperature is a well-known phenomenon. Many of our towns, like Dehra Dun, Bangalore, Pune and Bhopal, which once were considered green and idyllic with pleasant and equable climate, have now heated up because of massive, thoughtless construction witnessed therein during the last few decades. Much of their old attributes could, however, have been retained had recourse been taken to “green construction”. Apart from being eco-friendly, it would have kept their ambience well within the comfort zone, retaining their salubrious attributes. Unfortunately, this didn’t happen as environmentalism has been a little late in taking roots in this country.

While “green construction”, with all its environmental benefits, can be made a reality by suitably organising/incentivising the relevant aspects of the construction industry governments, in the meantime, could encourage the concept of “green roofs”. These are also to a great extent environment-friendly. Massive constructions taking place in all urban concentrations are propelling demands for energy, besides heating up their environment. Green roofing, if introduced, particularly in large constructions/complexes, could mitigate to a large extent their ill-effects

“Green roofs” are not the ones that are strewn with plants in pots or containers. The term refers to a roof that is partially or wholly covered with vegetation and soil on top of a waterproofing membrane. Not an unknown phenomenon, one recalls at least one building around 20 years ago in South Mumbai on the roof of which fairly good-sized trees could be seen swaying in the breeze from the road below.

Historically speaking, however, green roofs first came up in Germany on top of low-cost apartments during the post-industrial constructions in the late 19th Century. The roofs were topped with gravel, sand and grass to protect the constructions from fire. Germany saw a second wave of “green roofs” during the 1980s to bring the fast-disappearing vegetation back into cities. Subsidies helped create around 63,500 square metres of green roofs by 1996. Made a legal requirement for all large construction projects, Germany today is estimated to have 10% of all its roofs “greened”.

It is not Germany alone where green roofs have taken off in a big way. France, Austria, Switzerland and other European have climbed on to the bandwagon. Switzerland has one of Europe's oldest green roofs, created in 1914, on a water-treatment plant in Zurich. Europe, currently, is estimated to have 15 million square metres of green roofing. Becoming increasingly popular in the US, the 2.5 acre-roof of San Francisco's new California Academy of Sciences building is being greened as habitat for indigenous species. While the largest expanse can be found at the Ford Motor Company’s plant in Michigan, Chicago’s City Hall is another well-known example. Fukuoka, in Japan, has 35,000 plants of 76 species on the terraces of its Prefectural International Hall as a compensatory measure for gobbling up the park it was built on.

World over cities are taking to green-roofing for their obvious public and private benefits. Among the major public benefits are insulation of buildings from extremes of temperature, reducing their energy requirements for heating/cooling thus preventing further global warming, re-creation of brownfield habitats of ecological value fostering regeneration of their bio-diversity; mitigation of air-borne pollution and risks of floods and enhancement of their visual appeal. More importantly green roofs cool overheated cities by reducing the Urban Heat Island Effect (UHIE) which makes urban concentrations, with their hard reflective surfaces, hotter than their rural surroundings (Chicago’s City Hall roof has been found several degrees cooler than the surrounding roofs). Besides, depressed UHIE reduces ground-level ozone, contributing to a healthier urban community.

Private benefits include, inter alia, substantial savings on energy for internal heating/cooling, provision of drains and storm water management. Besides insulating the building from external noise, green roofs extend aesthetic advantage, providing congenial spaces for rest and recreation. They even have economic value. A hotel in Vancouver saved more than its investments on its green roof by growing herbs it used in its cuisine and a farmer in Chhattisgarh grew his crop on his small rooftop patch. What’s more, they increase the value of the property.
As retrofitting of existing roofs is eminently feasible the central and the state governments could launch a campaign and incentivise green roofing, particularly in large constructions/complexes, for its all-round benefits, more so for the wellbeing of the rapidly growing urban communities. An enactment on German pattern could also be considered