‘Green Building’ concept
Er. Prabhat Kishore
People spend major part of their life time indoors, i.e. inside the buildings, which may be their homes, offices, hospitals, shops, factories, educational and other places. The time varies from 60 to 90 percent depending upon the nature of jobs and livings.
According to UNEP, these buildings are a major source of carbon emissions (nearly 39%) causing global warning. Depleting natural resources, rapid industrialization and urbanization have led a negative impact on the environment and life-cycle. To tackle this source of global warming, “Green Building” concept has evolved.
A Green Building is one which uses less water, optimizes energy efficiency, conserves natural resources, generates less wastes and pollutions and provides healthier space for its occupants as compared to a conventional building. A green building in its design and construction minimizes negative impacts.
It is based on “Triple Bottom Line (TBL)” benefits, which accounts for social and environmental performances in addition to financial performance. The concept is also termed as 3P approach – People, Planet and Profits.
In India, as per census 2011, nearly 31.16 % population is living in urban areas. The government had informed Lok Sabha that by 2050, nearly 60% of population will live in cities as India’s rate of urbanization is dramatic. There has been increase in nearly 700% commercial energy consumption in last four decades and there is water shortage of nearly 225 million liter per day (mld) in major Indian cities. World Wildlife Fund (WWF) survey report reveals that, 100 cities, including 30 in India, may face acute water shortage by 2050.
In Indian context, a Green Building construction contains, as its components, all Panch-bhootas (5 manifestations of nature), i.e. Prithvi (Bhumi, earth)- Sustainable sites and materials, Apas (Jal, water)- Water efficiency, Agni (Fire)- Energy efficiency, Aakash (Space)- Daylight and atmosphere, and Vayu (Air)- Indoor environmental quality and pollution measures.
Prithvi- Material Efficiency
Materials for construction should be obtained from natural, renewal sources managed in a sustainable manner. It can be obtained locally to reduce the embedded energy cost of transportation or salvaged from reclaimed materials at nearby sites. Materials are assessed at their life cycle analysis (LCA) in terms of their embedded energy, durability, recycled contents, minimum wastes and their ability to be recycled.
In-fill development, that increases density, is inherently better than building on undeveloped (Greenfield) sites. Mixed-use development, in which residential and commercial uses are intermingled, can bring down automobile use and help to create healthy communities.
Apas- Water Management
In green buildings, water use is minimised through water efficient appliances, self-closing or spray tapes, low flush toilets or waterless compositing toilets. Use of potable water is discouraged in non-potable applications such as landscaping or indoor plumbing needs. Rainwater and Greywater (i.e. water emanating from sinks, showers, bath tubs or cloth washers) catchment systems are installed, which recycle such water for toilet flushing & irrigation purposes.
Due to urbanization, infiltration of rain water into sub-soil has decreased and recharging of ground water diminished, so “Rain water harvesting” is essential for a building. Rain water may be stored on surface for future use or may recharge to groundwater.
Agni- Energy Efficiency
Green building incorporates energy efficient lighting, low energy appliances and renewal energy sources such as solar panels and wind turbines. The passive solar design, high levels of insulation and energy efficient windows bring down the heating as well as cooling cost of the building. Passive solar power design is a part of the building itself and have heat absorbing surface materials and strategic placement of windows.
It employs sunshine to heat, cool and light the building without mechanical and electrical devices. In this design, the building should be elongated on east-west axis and its south face should receive sunlight during heating seasons. Interior spaces, requiring most light as well as heating & cooling, should be along south face of the building and less used space on the north face. The two primary elements are south facing glass and thermal mass to absorb, store & distribute heat. Compact Fluorescent Lights (CFL) are energy savers, as incandescent bulbs use only 10% of energy into light and rest 90% produces just heat.
Actually active solar power panels would be more effective and produce sufficient energy requirement of the house as India has enormous scope of renewal energy. But its upfront installation costs are high and available equipments are of poor quality and short life, which discourages the common people. The government should give emphasis for research on renewal energy, particularly solar energy, so that the good quality equipments be available at optimum rate to all sections of the society which ultimately will aid in reducing greenhouse gas emission.
Aakash- Daylight Harvesting
Natural daylight design is the way to collect and utilize natural day-light in the interior of the building, when available, to reduce the need for energy-consuming artificial lighting. Green buildings are designed to maximize that light and distribute it effectively deeper into the building.
A common design of daylight harvesting uses passive devices known as “Light shelves” to direct daylight back up and further into a space by bouncing it off the ceiling. The light shelf may be polished or reflective, and the ceiling must be of a light colour with good reflective quality. This method of providing “indirect” natural light delivers a good quality of light – diffuse and glare-free – that is superior to direct daylight and especially direct sunlight. Natural light is more pleasant, healthful and psychologically beneficial than artificial light. Daylight harvesting can reduce energy consumption and costs of building lighting by over 25%.
Vayu- Health Concerns
Non-toxic, ethical and sustainable materials should be used to improve the indoor air quality and to lessen the rate of asthma, allergy and sick building syndrome. These materials are emission free, have low VOC content and are moisture resistant to deter moulds, spores & other microbes. Indoor air quality is improved through proper ventilation system and use of materials controlling humidity. Plantation is also an important ingredient for green buildings depending upon the available space. In case of limited space in the house, Tulsi, Aloe Vera & other herbal/medicinal plants in flowerpots would be a better solution.
In foreign countries, the “Green Building” concept is gaining momentum. In India too, it needs to be popularized through enacting proper laws as well as community involvement. In first phase, all government buildings as well as manufacturing and construction industry sectors should adopt this concept and then by popularizing its benefits with sufficient proof, people should be encouraged to adopt this concept in their houses.
Life on earth is secure so long as nature is pure. So nature must be conserved, restored and used sustainably while simultaneously meeting other global societal goals through urgent and concerted efforts. For fostering transformative changes, “Green Building” concept is the pivotal solution.
(The author is a technocrat and an academician. He holds Master in Engineering from M N Regional Engineering College, Allahabad/Prayagraj)