Various aspects about green buildings are given here.
What is a green building?
A green building depletes as little of the natural resources during its construction and operation. The aim of a green building design is to
- Minimize the demand on non-renewable resources and maximize the utilization efficiency of these resources when in use
- Maximize reuse and recycling of available resources
- Utilization of renewable resources.
It maximizes the use of efficient building materials and construction practices; optimizes the use of on-site sources and sinks by bio-climatic architectural practices; uses minimum energy to power itself; uses efficient equipment to meet its lighting, air-conditioning, and other needs; maximizes the use of renewable sources of energy; uses efficient waste and water management practices; and provides comfortable and hygienic indoor working conditions.
The following aspects of the building design are looked into in an integrated way in a green building:
- Site planning
- Building envelope design
- Building system design HVAC (heating ventilation and air conditioning), lighting, electrical, and water heating
- Integration of renewable energy sources to generate energy onsite
- Water and waste management
- Selection of ecologically sustainable materials (with high recycled content, rapidly renewable resources with low emission potential, etc.)
- Indoor environmental quality (maintains indoor thermal and visual comfort and air quality)
Benefits of green buildings
There are many benefits of green buildings and green development. The following are a few :
- Enhance and protect biodiversity and ecosystems
- Improve air and water quality
- Reduce waste streams
- Conserve and restore natural resources
- Reduce operating costs
- Improve occupant productivity
- Enhance asset value and profits
- Optimize life-cycle economic performance
- Enhance occupant health and comfort
- Improve indoor air quality
- Minimize strain on local utility infrastructure
- Improve overall quality of life
Process to rate green buildings
GRIHA, an acronym for Green Rating for Integrated Habitat Assessment, is a rating tool that helps people assesses the performance of their building against certain nationally acceptable benchmarks. It evaluates the environmental performance of a building holistically over its entire life cycle, thereby providing a definitive standard for what constitutes a ‘green building’. The rating system, based on accepted energy and environmental principles, will seek to strike a balance between the established practices and emerging concepts, both national and international.This tool has been adopted by the Ministry of New and Renewable Energy. This tool, by its qualitative and quantitative assessment criteria, is able to ‘rate’ a building on the degree of its 'greenness'.
Examples of green buildings
Some of the examples of green buildings are
- Govardhan Eco Village: Soil Biotechnology Design
- CESE (Centre for Environmental Sciences and Engineering) Building, IIT Kanpur, Uttar Pradesh
- Suzlon One Earth, Suzlon Energy Limited, One Earth, Hadapsar, Pune 411 028
- University of Petroleum and Energy Studies, Dehradun: Net Zero Waste Generation Design
- Indira Paryavaran Bhavan: Net Zero Building Design
This is a Net Zero Building. This means that this is a structure with zero net energy consumption where the total amount of energy used in the premises on an annual basis is more or less equal to the amount of renewable energy created on the site. “Total energy savings of about 40% has been achieved by adoption of energy efficient ‘chilled beam’ system of air conditioning. This is an innovative air conditioning system, where air conditioning is done by convection currents rather than air flow through diffusers and chilled water is circulated right up to the diffuser points unlike the conventional systems”, said an official statement.
Effective ventilation has been achieved by orientating the building in an East-West direction, separating different blocks with connecting corridors and having a large central court yard. The design is such that 75% of natural daylight is utilised to reduce energy consumption. With an installed capacity of 930 KW peak power, the building has the largest roof top solar system among multi storied buildings in India. Green materials have been used like fly ash bricks, regional building materials, materials with high recycled content, high reflectance terrace tiles and rock wool insulation of outer walls.
Reduction in water consumption has been achieved by use of low discharge water fixtures, recycling of waste water through sewage treatment plant, use of plants with low water demand in landscaping, use of geothermal cooling for HVAC system, rain water harvesting and use of curing compounds during construction. Because of the changes in the building design, a 67.3% reduction in energy consumption as compared to GRIHA benchmarks has been achieved. This is a 5-star GRIHA rated building.
- HAREDA: Solar Passive Design
- Infosys, Pocharam: Radiant Cooling Design
A green sewage management technology called Soil Biotechnology has been used to, which helps in recovering about 95% of the sewage water and reusing it for landscaping, etc. It is an attempt towards water conservation and preventing water pollution. This system consists of an impervious containment and incorporates soil formulated granular filter media, select culture of macro organisms such as earthworms and plants. Combined grey and black water from the cottages is collected and transported via underground sewage network to a central location.
The process by design integrates with the natural bio-geochemical cycles of nature. Purification takes place by absorption, filtration and biological reaction. The process operates in aerobic mode, thus eliminating the possibility of foul odour.The processed water can be reused for gardening, agriculture and supporting marine life. This project has achieved a 5-star GRIHA rating.
Incorporation of solar passive techniques in a building design helps to minimise load on conventional systems such as heating, cooling, ventilation and lighting. The campus has an air conditioned area of 1912 m2 and a non-air conditioned area of 2328 m2. This campus falls in the composite climatic zone, predominantly requiring cooling and heating in summer and winter respectively to maintain thermal comfort for the occupants.
Design of an Earth Air Tunnel using the geothermal property of the earth has been resulted in a reduction of more than 15% of the building cooling load. Efficient condenser cooling through a on-site water body and use of thermal energy storage has increased the efficiency and reliability of the air conditioning system.
Building design and envelope has been optimised through selection of appropriate wall and roof construction and through adoption of solar passive methods to provide shading devices for windows and roof, which would reduce energy demand to condition the spaces. The high performance glass for windows, while allowing light inside, does not allow heat and also keeps office cool from inside during the day, decreasing the load on HVAC systems. There is a 47% reduction in energy consumption and 65% reduction in water consumption as compared to GRIHA benchmarks. This a 5-star GRIHA rated building.
Suzlon One Earth is a 100% renewable energy campus with both on- and off-site renewable energy, that includes solar and wind. Out of this, 7% of the total energy consumption comes from 18 on-site hybrid wind turbines, solar panels and photovoltaic cells and 93% of the remaining is from off-site wind turbines. This building has 154.83kW renewable energy incorporated. 100% of the outdoor lighting and the communication server are run on renewable energy resources. The orientations of the blocks are such that the majority of building facades face North, South, North-west and South-East. This enables adequate day lighting and glare control. Glazing on the first and second floors has been shaded from direct solar radiation using louvers. High efficiency mechanical systems integrated with the efficient building envelope ensure that the energy consumption of the building is reduced significantly. This is a ‘Net Zero Energy for Lighting’ building. The energy consumption is met through on-site generation.
The HVAC scheme is designed innovatively combining various energy efficient components like pre-cooling of fresh air, heat recovery/exchange mechanisms to minimise overall energy consumption. Photovoltaic systems, and micro wind turbines are integrated in the design. In totality, Suzlon One Earth, with its innovative and integrated design solutions has managed to reduce its energy consumption by 47.2%, below the benchmarked energy consumption by GRIHA . This project has achieved a 5-star GRIHA rating.
The campus has ‘Net Zero Waste Generation’. A planned and extremely methodical waste management system is key to this tag. The sewage treatment plan installed in the campus is based on the activated sludge process. All the waste water generated in the campus is channelized to this sewage treatment plant (STP). The campus also has a bio-digester, which disintegrates all the organic waste generated. The bio-digester generates slurry from the organic waste while the STP releases treated water and slurry. The water is of tertiary standards and is used for irrigation. The slurry released from both sources is dried and used as manure. The excessive bio-fertiliser is packed and sold in the market.
42.73% reduction in energy consumption and 33.16% reduction in water consumption as compared to the GRIHA benchmarks have been observed by the GRIHA auditors, due to the sustainable building design practices that have been incorporated in the building. This project has achieved a 4-star GRIHA rating.
The building is one of its kind in the country in having energy autonomy by incorporating the latest and futuristic energy efficient concepts. This building is constructed based on solar passive design techniques, having building integrated photovoltaic (BIPV) system of 42.5kW capacity. Also this building also makes use of solar chimneys. A solar chimney is a way of improving the natural ventilation of a building by using convection of air heated by passive solar energy. Misting is done in the courtyard to cool the ambient air, which is circulated into the building through solar chimneys. The achieved internal air relative humidity ranges from 60-75 per cent. Evaporative cooling, cavity walls, fly ash based bricks, etc., have been incorporated. Incorporation of these features has resulted in achieving an internal temperature of about 20 degree Celsius without air conditioning. There has been 61% energy consumption reduction as compared to the GRIHA benchmark. The estimated energy consumption was to be about 30kWhr/m2/year in comparison to the consumption of about 200 kWhr/m2/year for the existing air conditioned buildings. This is a 5-star GRIHA rated project.
Infosys, Pocharam is the first commercial radiant cooled building in India. This building has proved that radiant cooling is more efficient than the conventional air conditioning system. In a conventional air conditioning system, air circulates in the room or premises to the cool surroundings. But when compared to air, water is more efficient in carrying energy that the same volume of air can carry. This property of water is used to achieve maximum advantage in a radiant cooling system. Cold water flows through pipes embedded in the slab and cools the entire slab and as a result the entire slab surface is maintained at about 20 degrees Celsius. Cooling inside the office space is achieved when the cold slab absorbs the heat (radiation) generated by people, computers, lighting and other equipment which are exposed to the slab. Fresh air is supplied through an air system to maintain a healthy indoor environment, and also to control the moisture inside the office space. The latent heat load (heat generated through release of water vapour like the one generated while we breathe out) is removed through this Dedicated Outdoor Air System (DOAS).
The radiant cooling also provides a healthier indoor air quality as there is no recirculation of air in the system. This technology also reduces the temperature of the slab improving the comfort of the occupants. The Infosys Pocharam campus has an air conditioning system which is 30-40% more efficient than the conventional air conditioning systems. 56% reduction in energy consumption and 56% reduction in water consumption as compared to GRIHA benchmarks have been observed.
Source : Innovations in Green Buildings