HUMAN beings spent 22-hours a day in the built environment and yet little attention is paid for ensuring that the buildings are free of pollution, are sustainable and environment-friendly. The United Nations Environment Programme (UNEP) report cautions that if the current practices of construction do not change, expansion of the built environment will destroy or disturb natural habitat and wildlife on 70 per cent of the earth’s land surface by 2032.
According to the report, the world population has more than doubled since 1950, with major growth having taken place in the developing countries. During the next 20 years, about 98 per cent of world population growth will occur in developing countries. By 2007, around half of this population will be living in urban areas.
In the developing countries, the share of population living in cities is expected to reach 40 per cent before the end of this decade, compared with less than 20 per cent in 1950. Some 60 per cent of the world’s fastest growing larger cities are in low-income countries. In terms of farmland alone, urbanization claims 40,000 sq km per year.
According to a Worldwatch publication, buildings are responsible for 40 per cent of the world’s total energy use; 30 per cent of raw materials consumption; 25 per cent of timber harvest; 35 per cent of the world’s carbon dioxide emissions; 16 per cent of freshwater, 40 per cent of municipal solid waste destined for local landfills and; 50 of ozone-depleting chlorofluorocarbons (CFCs) still in use. Buildings also affect watershed, habitat, air quality and community transportation.
Conventional building construction revolves around preparation of building plans, their approval and construction. Sustainable building construction, on the other hand, is a holistic and multidimensional approach, which includes, the materials assessment, processes used for construction, its influence on environment, transportation, indoor environmental quality and, the disposal of waste. Thus “construction” is only a part of sustainable building construction.
Like any other project, buildings and their construction have major environmental impacts. These includes raw material extraction and consumption, energy use, air pollution (emission of greenhouse gases), dust emissions during construction, indoor air pollution, noise pollution, use of water, solid waste and water generation, land-use modification, site clearance, aesthetic degradation (in the context of Karachi, this aspect is very strong), health risks for construction workers and building occupants, impacts of transportation of building materials to site (truck-related vehicle emissions; increased traffic and, the impacts on road traffic.
Similarly, there are many buildings in Karachi, where indoor air is so polluted that one gets suffocated. Ozone from copying machines, methyl alcohol from spirit duplicators, butyl methacrylate from signature machines, trinitrofluorenone from laser printers, ammonia and acetic acid from blueprint machines and, formaldehyde from carbonless copy paper can be found indoors where ventilation rates are poor. Radon, formaldehyde, volatile organic compounds, pesticides and biogenic particles (sources of asthma and allergies) are some of the most common indoor air pollutant. Legionnaires’ disease (pneumonia, cough, respiratory problems) is caused by a bacterium, Legionella pneumophila, which thrives on poorly maintained air-conditioning system. In Karachi, bronchial asthma caused by the indoor air is common.
To make the buildings sustainable in Karachi, the building regulatory agency needs to change its old conventional role and adopt a holistic approach to the buildings control and construction. Sustainable buildings (also known as green buildings, or eco-efficient buildings) have many salient features tagged to them. “Cradle-to-cradle design” pertains to the concept of viewing building materials as a closed-loop cycles of production, use and reuse.
There is no wastage of material. Cement, for example, is one important building material. Its production produces carbon dioxide, nitrogen oxides, sulphur oxides, dust, dioxins and furans (dioxins and furans are carcinogenic). So, if judicious use of cement is made and use of concrete (mixture of cement, water and aggregates) is optimized, exploring reuse options, wherever technically possible, one can reduce the consumption of resources [materials, energy (electricity, gas)] and reduce environmental pollution.
Another term used is the, ‘life-cycle assessment’ LCA) which means evaluation of environmental impacts associated with the production and use of a system, from first stage to the last. In case of cement, this means extraction and their transportation, use of fuel, gas, water and electricity, manufacture of cement, transportation to the site, making of concrete, erecting, painting and dismembering of column and its fate after dismembering.
Natural resources are the basis of life today and for future generations. Judicious use of natural resources, including recycling and reuse, can make them sustainable, thus usable for future generations.
In view of water shortages, its use in buildings has become major concern. Water conservation could be adopted, which would reduce its consumption by as much as 30 per cent. Optimizing the building orientation, so as to capture summer breeze and take advantage of shading provided by nature, can help in reducing the air-conditioning loads.
Use can be made of natural lighting, entailing savings of electricity. Construction can be done in such as way, so as to minimize production of waste. ‘Volatile organic compounds’ VOC) emissions are harmful for health. Designers can specify materials with no or low VOCs. Design should ensure that no indoor air pollution is caused and the air exchange rates (expressed as air change per hour) are such that they maintain adequate ventilation. Finally, landscaping with features so as to provide natural outlook, compatible with the natural environment can make building environment friendly.
The local building authority needs to have a environmental action agenda which should aim at reducing environmental impacts of buildings and keep urban environments clean and liveable. The agenda should target resource efficiency, waste reduction, human risks, environmental risks and environmental pollution prevention. It should ensure that future construction do not generate increased transportation. It should restore ecological functions, urban green areas (protect what is left of Karachi’s natural system) by managing built environment through sustainable orientation.
Some possible tips for solution could be: no building be allowed within 30 meters of any wetland and, on land whose elevation is lower than 1.5 meters above the mean sea-level; making carpooling/vanpooling mandatory in buildings in areas, which face traffic jams; buildings should have native or adopted vegetation; buildings should reduce heat islands (thermal gradient difference between developed and non-developed areas); buildings should not trespass light (night sky pollution); buildings with relatively large roof area, should have the provision of harvesting rainwater for landscaping and cleaning; building developers should submit annual reports on indoor air quality; buildings should not have CFC-based refrigerants in the air-conditioning systems and, halons in fire suppressing systems; buildings should optimize energy performance; buildings should make maximum use of renewable energy (the proposed 541-meter high Freedom Tower at ground zero, Manhattan (New York), will have wind turbines to generate part of the electricity); buildings should have an area, earmarked for separation and collection of recyclables; non-smokers should not be exposed to ‘environmental tobacco smoke’ (ETS); non-smokers’ problem can be easily handled by providing a designated smoking place, where powerful exhaust fans exhaust the smoke outdoors.
Rational building designs and materials selection can help in reducing the environmental impacts. Prudent strategy can actually improve the deteriorated environments and increase the comfort of building occupants.
In Karachi, when there is any violation of the building laws, the building regulatory agency demolishes the violated portion of the building. It would be very helpful for the environment, if the building regulatory agency dismember, deconstruct or disassemble the violated portion of the building, so that, the dismembered or disassembled parts can be reused or recycled, rather than having it demolished and, turning it to waste (a resource depletion), which is a loss to the public. It is known that, one person’s waste, can be a useful material for another person.