IntroductionBuildings in India have been influenced from British Architecture as a result of colonization for around 200 years. Even after over 50 years of independence the fact remains that our cities are still symbolized by pre-independence buildings. For an instance Kolkata is symbolized by Victoria Memorial, New Delhi by Rashtarpati Bhawan, Chennai by Victoria Memorial Hall and Mumbai by Victoria Terminus. Buildings constructed in post independence era have little to offer in terms of architectural significance. Introduction of green building concept in the arena of architecture and planning has proved to be a landmark. Ever since the emergence of LEED concept, notable buildings such as CII GBC at Hyderabad, ITC Green Centre and Wipro Technologies at Gurgaon have been added to the list. The main reason behind the adoption of this concept is that green buildings help in increasing the efficiency with which a building uses resources, energy, water and minerals and at the same time reduces the impact of the building on human health¹ (protects the occupants from sick building syndrome) and environment. This is done through better site planning and design, construction, operation and maintenance and improves the life cycle of the building.
Like any human being or a living organism, buildings also have a life cycle which has a direct impact on the environment within the building, on the occupants of the building and also on the surroundings of the building. Raising of structures/ buildings involve the extensive use of building materials and depletion of resources such as ground cover, water, forest, energy etc. Sustainable development has now become an important aspect of real estate and construction industry. A building contributes to global environmental issues due to production of waste effluents, solid waste, carbon dioxide emissions, use of land, improper use of water, raw material and energy consumption (Source: UNEP 2007). This in fact, is a result of the operations within the building and functions performed by the occupants of the building. Energy consuming devices installed to achieve the comfort levels for the occupants of the building gives rise to heat generation which adversely affects the environment within the building and in the surrounding. Buildings are thus the major pollutants that affect the urban air quality and contribute to climate change. Buildings are the major consumers of energy during their construction, operation and maintenance. It has been estimated that about 50% of the global energy demand is estimated due to the buildings. The energy requirements in buildings are increasing at a high pace in developing countries with rising economy. Energy consumption for buildings in India accounts for 30–40% of the total energy consumption.
Though LEED concept has been introduced in 2000, but the green building concept is not new in India. As we all know that our ancestors worshipped five elements of nature: Prithvi as Earth, Agni as Fire, Jal as Water, Vayu as Air and Akash as Sky. The idea behind LEED rating also indicates emphasis on the optimum utilization and conservation of these resources. Hence it shows that the concept has been developed from Indian ethos. It ensures environmental protection, water conservation, energy efficiency, use of recycle products and renewable energy.
Significance of Climate in Green DesignKnowledge of climatic conditions of a given location is vital for a good design. Different locations within large areas have almost similar climatic characteristics which can be grouped together to form climatic zones within which climatic requirements for buildings are generally same with few differences only due to local environmental conditions. Life patterns of people, activities and behavior are influenced by the elements of climate. The basic elements viz. air temperature, solar radiation, humidity; rainfall and wind form the general climate of a place.
Bureau of Indian standards has divided Indian climate broadly into the following 5 climatic zones:
- Hot and Dry zone
- Warm and Humid zone
- Temperate zone
- Cold zone
- Composite zone
Design Features for Different Climatic Zones in India
This type of climate generally prevails in parts of northern India, Shillong, Mahabaleshwar, Ootacamund. These are generally highland regions having abundant vegetation in summer. The intensity of solar radiation is low in winter with a high percentage of diffuse radiation. Hence, winters are extremely cold. Therefore air heating panels act as an integral component of the building design to provide effective heat gain. Double glazed windows with sealing help to minimize infiltration. In summer, the maximum ambient temperature is in the range of 20– 30ºC during the day and 17–27ºC at night, making summers quite pleasant. In winter, the values range between 4 and 8ºC during the day and from -3 to 4ºC at night, making it quite chilly. Therefore it is important that windows and light shelves should be carefully integrated to ensure effective daylight distribution. The relative humidity is generally high and ranges from 70–80%. Annual total precipitation in this zone is about 1000 mm and is distributed evenly throughout the year. These areas experience cold winds in winter season. Hence, protection from winds is essential in this type of climate. The sky is overcast for most part of the year except during the brief summer. Conditions in summer are usually clear and pleasant, but owing to cold winters, the main criteria for design in the cold region aims at resisting heat loss by insulation and infiltration, and promoting heat gain by directly admitting and trapping solar radiation within the living space. Specially designed solar air heating systems should be installed at roof tops with duct systems for supplying at various places.
Example: HP State Cooperative Bank Building, Shimla
- South-facing Trombe wall and sunspace heats up the interior
- South-facing solar collectors on the roof provide warm air, which is circulated by means of ducts
- North face is protected by a cavity wall that insulates the building from prevailing winter winds
- Western wall is provided with insulation as well as double glazing
- Day lighting is enhanced by providing light shelves. Skylight on the terrace also provides daylighting
- Air lock lobbies are provided to reduce air exchange
Composite ZoneThis zone covers the central part of India. Major cities falling under this type of climate are New Delhi, Kanpur and Allahabad. This zone is rich in landscape and seasonal vegetation. The intensity of solar radiation is very high in summer with diffuse radiation amounting to a small fraction of the total. In monsoons, the intensity is low with predominantly diffuse radiation. The maximum day time temperature in summers is in the range of 32 – 43ºC, and night time values are from 27 to 32ºC. In winter, the values are between 10 to 25ºC during the day and 4 to 10ºC at night. The relative humidity is about 20–25% in dry periods and 55 – 95% in wet periods. The presence of high humidity during monsoon months is one of the reasons why places like New Delhi and Nagpur are grouped under the composite and not hot and dry climate. Precipitation in this zone varies between 500–1300 mm per year. This region receives strong winds during monsoons from the south-east and dry cold winds from the north-east. In summer, the winds are hot and dusty. The sky is overcast and dull in the monsoon, clear in winter and frequently hazy in summer. Generally, composite regions experience higher humidity levels during monsoons than hot and dry zones. Otherwise most of their characteristics are similar to the latter. Thus, the design criteria are more or less the same as for hot and dry climate except that maximizing cross ventilation is desirable in the monsoon period.
Example: Solar Energy Centre, Gurgaon
- Roof surface evaporative cooling system
- Appropriate planning in which laboratories requiring air conditioning are put together in a well-insulated building
- Hollow concrete block walls to resist heat gain by conduction
- Reflective finish on roof surface
- Windows designed for cross ventilation and day lighting. The east and west facing windows incorporate openable louvered shutters
Moderate zonePune and Bangalore are examples of cities falling under this climatic zone. Areas having a moderate climate are generally located on hilly or high-plateau regions with fairly abundant vegetation. The solar radiation in this region is more or less the same throughout the year. Being located at relatively higher elevations, these places experience lower temperatures than hot and dry regions. The temperatures are neither too hot nor too cold. In summers, the temperature reaches 30–34ºC during the day and 17– 24ºC at night. In winter, the maximum temperature is between 27 to 33ºC during the day and 16 to 18ºC at night. The relative humidity is low in winters and summers, varying from 20–55%, and going upto 55–90% during monsoons. The total rainfall usually exceeds 1000 mm per year. Winters are dry in this zone. Winds are generally high during summer. Their speed and direction depend mainly upon the topography. The sky is mostly clear with occasional presence of low, dense clouds during summers. The design criteria in the moderate zone are to reduce heat gain by providing shading, and to promote heat loss by ventilation.
Example: Centre for application of science and technology for rural areas (ASTRA), Bangalore
- Sized stone masonry with composite mortars in foundations, steam-cured stabilized blocks for ground floor load bearing walls, and soil-cement blocks for the first floor walls. The external exposed walls are coated with transparent silicone paint for protection from erosion.
- Precast chajjas and brackets are made of ferrocement.
- Reinforced block work lintels are used above openings such as doors and windows.
- Soil-cement block filler slabs are used for floors and roof. An additional weatherproof course using tiles is provided on the roof.
Warm and Humid zoneThe warm and humid zone covers the coastal parts of the country. Some cities that fall under this zone are Mumbai, Chennai and Kolkata. The high humidity encourages abundant vegetation in these regions. The diffuse fraction of solar radiation is quite high due to cloud cover, and the radiation can be intense on clear days. The dissipation of the accumulated heat from the earth to the night sky is generally marginal due to the presence of clouds. Hence, the diurnal variation in temperature is quite low. In summer, temperatures can reach as high as 30–35ºC during the day and 25–30ºC at night. In winter, the maximum temperature is between 25 to 30ºC during the day and 20 to 25ºC at night. Although the temperatures are not excessive, the high humidity causes discomfort. An important characteristic of this region is the relative humidity, which is generally very high, about 70–90% throughout the year. Precipitation is also high, being about 1200 mm per year, or even more. Hence, the provision for quick drainage of water is essential in this zone. The wind is generally from one or two prevailing directions with speeds ranging from extremely low to very high. Wind is desirable in this climate, as it can cause sensible cooling of the body. The main design criteria in the warm and humid region are to reduce heat gain by providing shading, and promote heat loss by maximizing cross ventilation. Dissipation of humidity is also essential to reduce discomfort.
Example: Auroville Ecohouse, Auroville
- Optimum orientation of built form for cooling by ventilation
- Shading of windows to reduce heat gain
- Alternative building materials such as (i) structurally insulated roof units (size 1.0m X 0.5m), developed by Central Building Research Institute, Roorkee, (ii) jack arches of hollow ceramic Gunna tiles
- A courtyard to enhance cross ventilation and provide day lighting
- Other features such as solar cooker integrated in south facing kitchen, rainfall harvesting system, biogas plant for waste management and production of methane gas for cooking, an aero- generator for domestic electric load and a thermosyphon solar water heater are also incorporated into the building design
Hot and Dry ZoneThe hot and dry zone lies in the western and the central parts of India; Jaisalmer, Jodhpur and Sholapur are some of the towns experiencing this type of climate. A typical hot and dry region is usually flat with sandy or rocky ground conditions, and sparse vegetation comprising cacti, thorny trees and bushes. There are few sources of water on the surface, and the underground water level is also very low. Due to intense solar radiation (values as high as 800-950 W/m2), the ground and the surroundings of this region are heated up very quickly during day time. In summer, the maximum ambient temperatures are as high as 40–45ºC during the day and 20–30ºC at night. In winter, the values are between 5 and 25ºC during the day and 0 to 10ºC at night. It may be noted that the diurnal variation in temperature is quite high, that is, more than 10ºC. The climate is described as dry because the relative humidity is generally very low, ranging from 25 to 40% due to low vegetation and surface water bodies. Moreover, the hot and dry regions receive less rainfall- the annual precipitation being less than 500 mm. Hot winds blow during the day in summers and sand storms are also experienced. The night is usually cool and pleasant. A generally clear sky, with high solar radiation causing an uncomfortable glare, is typical of this zone. As the sky is clear at night, the heat absorbed by the ground during the day is quickly dissipated to the atmosphere. Hence, the air is much cooler at night than during the day. In such a climate, it is imperative to control solar radiation and movement of hot winds. The design criteria should therefore aim at resisting heat gain by providing shading, reducing exposed area, controlling and scheduling ventilation, and increasing thermal capacity. The presence of “water bodies” is desirable as they can help increase the humidity, thereby leading to lower air temperatures. The ground and surrounding objects emit a lot of heat in the afternoons and evenings. As far as possible, this heat should be avoided by appropriate design features.
Example: Inspector General of Police (IGP) Complex, Gulbarga
- Passive downdraft evaporative cooling (PDEC) towers for providing comfort
- Tinted glasses to reduce glare
- Alternative building materials such as composite walls to reduce heat gain and filler slabs to reduce the quantity of concrete in the structure
- A central atrium to enhance cross ventilation and provide day lighting
- Solar PV lighting and pumps, rainfall harvesting and water conservation facilities incorporated
Thus, in brief, an energy-efficient building balances all aspects of energy use in a building – lighting, space-conditioning, and ventilation – by providing an optimized mix of passive solar design strategies, energy efficient equipment, and renewable sources of energy. Use of materials with low embodied energy also forms a major component in energy efficient building designs.
Reckless and unrestrained urbanization, with its haphazard buildings, has bulldozed over the valuable natural resources of energy, water, and ground cover, thereby greatly hampering the critical process of eco-friendly habitat development. However, it is not too late to retrace the steps. The resource crunch confronting the energy supply sector can still be alleviated by designing and developing future buildings on the sound concepts of energy efficiency and sustainability. Energy efficiency in buildings can be achieved through a multipronged approach involving adoption of bioclimatic architectural principles responsive to the climate of the particular location; use of materials with low embodied energy; reduction of transportation energy; incorporation of efficient structural design; implementation of energy-efficient building systems; and effective utilization of renewable energy sources to power the building.
India is quite a challenge in this sense. As already discussed India has been broadly divided into five climatic zones (Cold, Hot & Dry, Composite, Warm & Humid and Temperate zone). Translation of bioclimatic architectural design in the Indian context, therefore, provides experience and success stories to learn from. Several buildings have come up, fully or partially adopting the above approach to design.
- Representative Designs of energy efficient buildings in India by TERI
- Map India 2005, Climate Classification for Architects, Engineers and Town Planners
- Green Buildings in India: Lessons Learnt by S Srinivas, CII Godrej, GBC Climate and Buildings
- Traditional Architecture and Planning Techniques in Himachal Pradesh by M Jain, I Singh, SC Sharma
- Science Technology Entrepreneurs Time 2009
- Green Buildings Costs and Financial Benefits by Greging H Kats