Making tall urban buildings green is necessary, but it will solve only a part of the problem
It appears that our understanding of the urban ecosystem in our cities will continue to limit our competence in providing environmentally and ecologically sustainable alternatives for urban habitats. One solution, experts argue, is to go vertical, while improving all the other needed services like roads, water and waste disposal. These are all no doubt”politically convenient” potions for the pains of our urbanitis. But as we advance into the 21st century, the economic costs of excessive growth and the associated instability is forcing us to see through the glitter of aluminum facades, neon signs and the romantic conquest of clouds by high-rise structures. Given the scarcity of land, the increasing population density of our cities is only adding to the pressure on available resources.
As a result, the first casualty has been the green spaces, the flood plains of the rivers and mangrove jungles in coastal cities which are the lungs and kidneys of these polluted urban centres. The second casualty is the excessive consumption of building materials produced from natural resources rendering these production lands desertified at the end of production cycle.
The only alternative to this are green habitats and lifestyles which have emerged during the past two decades. Green buildings are typically constructed using materials made from fly ash, inert portions of solid and hazardous wastes and from pulverized construction debris. Fake wood, wall panels and insulation boards from waste biomass, agricultural wastes as well as wasted woods and plastics recovered from garbage are available. Paints free from heavy metals and made from non-toxic organic dyes and pigments and using water as solvent rather than carcinogenic organic solvents and thinners are encouraged in green buildings.
The architecture of green buildings is such that they are capable of harvesting solar radiation for lighting, cooking and water heating. From their inception, green buildings need to minimise consumption of potable water by installing water saving devices.
Recently, the Maharashtra government appointed a committee to study the proposals of high rise buildings (more than 21 storeys or 70m height) and recommend the suitability of design features and approve the structures. In some high-rise proposals approved by the committee, several green provisions were made mandatory to minimize its environmental and ecological footprint.
For example, the domestic water supply to these high rise buildings will be 90 litres of potable water per person per day. Sewage water will be treated to high standards and reused it for the flushing, landscaping and gardening. Mumbai thus is the first city making sewage water treatment and reuse mandatory for all high-rise buildings. The committee has also tried to motivate developers in improving other environmental services like solid waste management, fire safety and energy conservation.
These features will enable these structures to qualify for the green building certification. The rating system for this is the most versatile and widely adopted green building certification system in the world. The Indian Green Building Council is working on a rating system to suit the Indian context. Reportedly, the commercial potential for constructing green buildings in India is four billion dollars.
Yet, making tall urban buildings green will solve only a part of the urban crisis. The other big problem is the inadequacy of collection and treatment of sewage and garbage disposal. Presently, our garbage is being dumped into poorly engineered landfills or low-lying areas, waste water barely treated and disposed in an environmentally unsound manner (only 25 per cent sewage in India gets some kind of treatment). It is high time that we see the problem of urban waste management in an integrated manner with other infrastructure and service issues.
The writer is Head of the Centre for Environmental Science & Engineering, IIT Mumbai.