Massive construction activities associated with the development of habitat have numerous environmental impacts and unless tackled properly may create ecological imbalance. In developing countries like India material producers and builders often use traditional, less energy efficient techniques or old fashioned highly polluting equipments. There is often a lack of knowledge about how to make production clean and energy efficient. Improvements might also be hindered by lack of capital, availability of indigenous equipments and weak management practices both in material production and their usage at construction sites might be other reasons for this status. Inadequate government policies and enforcement mechanism to encourage designers and builders to adopt environment friendly technologies in construction and standards and building regulations also cause continued use of energy intensive materials and technologies.

Complex, highly dispersed and resource demanding nature of activities in the construction sector contributes to the loss of important and limited natural resources like timber, metal and mineral resources which later on imposes severe stress on the environment. Construction activities also attributes towards release of ozone depleting substances that damage the ozone layer. There is a need of a concerted, integrated approach for building eco habitat which alone can minimise the adverse impacts on the environment and reduce the consumption of natural resources over the building life.

There is growing concern about increasing land dereliction, caused by extraction of sand, gravel and clay, etc., which alternately reduces the land available for habitat development. Brick making activity alone consumes, at present, an equivalent of 300 mm depth from 100,000 hectares (1000 sq km) of fertile land. Similarly the pressure on raw materials like limestone to manufacture cement and energy requirement to produce these materials are required to be addressed.

Construction activities can be detrimental to coasts and water esources, which can become critical in some areas. The extraction of sand and gravel from river beds and beaches can have serious environmental consequences like precipitating soil erosion. The use of coral as an aggregate or building stone is also common in parts of India. Logging practices causes increased rate of erosion, increased sediment loads, and also affect habitats for plant and river organisms downstream. It is, therefore, necessary to strictly implement the coastal zone regulations for all construction activities.

Forests are an important natural resource base, which play a crucial role in the conservation of watersheds, prevention of soil erosion and balancing the eco-system. Forests are also sources of domestic energy supply such as wood for cooking and heating and of fuel for brick and lime production in rural areas. There is also increasing concern about the destruction of the tropical forest and the adverse impact of this on the environment. Managing the forest in a sustainable manner, so as to minimise the rate of deforestation, is therefore, imperative and should be given highest priority.

Non-renewable resources used in construction include fossil fuels, metals and minerals such as stone and clay. Supply of some of these may last only a few decades. Although more pockets of these resources are discovered and new technology might extract more than is possible today, the rate at which the reserves are depleting means consumption must be controlled and renewable resources must replace these traditional materials.

The construction sector is a major user of energy. Energy is required for manufacturing materials, for transportation and for construction of buildings. Apart from initial energy usage, there is also need for energy to operate buildings during its life time.

Embodied energy in buildings is related to the production of raw materials used for construction, while construction activities and transportation account for a smaller proportion. This can be classified in three categories:

A considerable amount of energy is used in buildings during their lifetime. This energy is required for heating, cooling, ventilation, lighting, cooking and other domestic activities.

The energy use patterns inside buildings vary a great deal according to occupants’ behavior, type of structure and location of buildings. In residential buildings, urban and rural patterns tend to be very different. Household income and climate have major influences both on the type of energy sources and end-use patterns.

Architects and engineers have a crucial role to play in designing buildings to minimise energy use for active climatisation and lighting. A good approach is to take advantage of natural means such as solar radiation and winds and use the building as a collector, storage and transfer mechanism. The knowledge of passive techniques is well developed but is unfortunately not yet effectively practiced.

A large number of industrial and agricultural wastes have found wide acceptance as alternatives to clay, limestone and various other argillaceous and siliceous materials in the production of bricks, tiles, cement, concrete slab and ceramics.

Table 1 Indicates a list of well established industrial, mining and mineral wastes and by-products and their use in production of building materials as developed in India.

Use of agro-industrial wastes not only helps in tackling the environmental problems but at many instances actually improves the properties and durability of building materials.

Scientific studies for in-depth analysis of available technologies for changeover to alternative fuel sources in manufacturing materials that will reduce Green House Gas emissions requires to be initiated. This need is being increasingly realised through the establishment of environmental regulatory mechanisms to ensure installation of pollution control systems which have already been developed and are commercially available in the country.

Any human settlement requires sufficient source of water for daily and other needs. With the rising population and over exploitation of ground water resources, it is important to conserve water. Rain water harvesting needs to be incorporated in the building bylaws as a mandatory requirement.

Integrated Waste Management is essential to ensure appropriate disposal and recycling of agricultural, municipal and industrial waste and preventing the indiscriminate abuse of precious land for dumping garbage. Sustainable waste management practices are required not only for municipal garbage but also for industrial refuse or bio-medical waste.

The analysis to discern the impact of the construction industry on the environment is very complicated. To assess how different materials and operations influence the environment over a longer period of time, it is worth considering a life cycle approach to materials and buildings.

Products achieving good ratings in life cycle assessments are based on renewable raw materials, produced with methods using low amount of energy and having low pollution, sound and non-hazardous for the users, etc.

Many industrial countries have developed the so-called eco-labeling schemes to promote production of environmentally friendly products. Products that meet the requirements get the eco-label, which works as a "guarantee" for consumers that the particular product is environmentally friendly. The increasing awareness among consumers of the importance of protecting the environment have made eco-labels important tools to market products.

In view of various details given in preceding paragraphs, it is important to focus on eco-habitat.

Eco buildings are designed to meet certain objectives such as protecting occupant’s health: improving employee productivity: using energy, water and other resources more efficiently; and reducing the overall impact to the environment. This is possible if an integrated approach to building design, at the initial stage itself, is followed which involves judicious use of application of:

The range of eco design features is very diverse with options that include energy efficient materials, passive solar considerations and structural and mechanical components. These all work together to create a building that is attractive and functional, saves utility costs over the life of the structure and has minimal impact on the environment.

A practical and integrated approach, based on achievable targets and realistic courses of action formulated on the basis of understanding of prevailing situation is required.

Based on the Global Plan of Action of the Habitat Agenda guidelines, actions are required to be formulated at national and state level on the following:

S. K. Gupta
Dy. Chief (TDE&IC)
Building Material Technology Promotion Council