Green buildings, also known as sustainable, energy ef`f`icient and smart buildings, are built with the aim to minimise environmental impacts, emitting none or very little amount of greenhouse gases (GHG) and reaping maximum environmental, social and economic benefits.

Generally, the direct and indirect benefits associated with green buildings include: reduced energy consumptions, increased water use efficiency, lower environmental impacts, reduced carbon emissions and air pollution apart from increased biodiversity, aesthetic value and provision of more space for food production.

In developing countries, conventionally built residential buildings, offices, shopping centres, parks and educational institutes are dependent on non-renewable energy resources to the maximum. Compared with conventional, green buildings provide, in theory, almost equal to natural environment, promote healthy living, minimise environmental impact and enhancewater conservation.

Given the climate in Pakistan, a green rooftop is a good idea to save energy especially in summer as they provide a cooling effect whilst acting as insulators in winter. Moreover, roofs can be used for growing vegetables and ornamental plants. In the present era, roof gardens are common in modern buildings, hotels, business eentres and private residences in developed economies but very rare in the developing world.

Site selection for a green building is of prime importance. According to Charles Lockwood, the site should have a parking area, roads and easy access to public amenities. From construction point of view, less dense soil can be a better insulator as it has more air sacks, while construction material made from bio-based products including plywood panels, composites, plastic-wood composite and medium density fibre-board and hardboard originating f`rom agricultural and / or natural bio fibres such as jute, straw, corn, I`lex, etc. are recommended to be used in green buildings.

More recently, scientists have introduced nano-based structural composite materials for this purpose. These light weight composites are not only durable and low cost but have proven to be good insulators, noise absorbers and resistant to extreme weather conditions. Interior fixings such as lighting in the building, location of` home appliances installation, use of water heaters, insulation of water pipes, sealing of` ducts, application of water conservation technologies including maintenance of` water pipes result in reduced energy consumption from 30-40 per cent in a green building.

After selection of a site, the building`s (proposed) design is of utmost importance to reapmaximum benefits of a green setting.

Although construction design and orientation should be in accordance with local environmental and climatic conditions, the direction of the building, windows and doors should preferably face towards the south depending on the route of the sun. Southward facing not only ensures max imum use of natural daylight but also results in improved ventilation and reduced carbon emissions. It is a well-known fact that a building facing southwards uses maximum sunlight, conserves energy and has improved indoor air quality.

It`s often said and is a fact that green buildings have much higher construction costs, but this extra spending pays back a lot more in terms of reduced utility bills, water conservation, improved indoor air quality, health benefits, lower operation and maintenance costs, greater productivity, etc.The cost of the building varies depending upon the type of building materials and installations being used. For example, installation of energy efficient appliances in the building can be more cost effective. Passive solar system can reduce 30-50pc bills with no additional cost.

Cost-benefit analyses are usually performed before initiating construction; all models predict an extra cost to build a green site but the benefits outweigh the extra cost which should be considered as investment to reduce monthly cost in term of water conservation and utility bills, etc.

In Pakistan, the idea for sustainable green construction began in 2005 after a devastating 7.8 Richter scale earthquake that hit the northcrn belt of Pakistan. Later, severe floods notably in 2010 across the country resulting in large scale collapse of infrastructure and non-sustainable buildings strengthened the concept, but no serious efforts have been initiated neither at government nor public level.

It is a need of the hour to set up a body to work with the green buildings idea initially in big cities and then focusing gradually to smaller cities and towns. Public-private partnerships could be highly advantageous to initiate this project; if it is subsidised by the government, it would catch public attention and prove to be a motivation for sustainable construction and healthy living.

Contrary to conventional buildings which contribute to environmental degradation along with human health problems, green buildings would contribute in production of clean air, decrease impact of climate change, solid waste management, rain water harvesting, wastewater treatment and reuse. Green buildings are one of the possible solutions to cope with energy and water shortages in the country. m The authors work at the Centre fòr Climate Research and Development (CCRD), COMSATS Institute of Information Technology (CIIT) Islamabad.

Email: saeed.asad@comsats.edu.pk