ECO Design: Sustainable Buildings for a New India

Most of today’s architectural expressions demonstrate human dominance over nature. That ‘The design process should leave a minimum footprint of man-made constructions on the environment’ is the philosophy that TERI abides by. This article focuses on some basic measures advocating sustainability for new built structures. – Mili Majumdar

ECO Design: Sustainable Buildings for a New IndiaShelter is a basic human need. Building and habitats are designed and constructed to fulfill this. Since the industrial revolution, the world has witnessed incalculable technological achievements, economic and population growth, and ever increasing use of natural resources. Increased urbanization, seen today, is a result of this overall growth. The green cover and ground water resources have been forced to give way to these rapidly developing urban structures.

Energy is another major resource that is being consumed indiscriminately to meet the power demand for air-conditioning, lighting and equipment. Citing an example of the growing urban metropolis of Delhi in India- it lost its green buffer to give way to the growth of satellite towns of Noida and Gurgaon, resulting in sudden weather changes due to unobstructed hot / cold winds from neighboring States. On the other hand, had these impacts been studied earlier, preventive interventions could have been possible.

Most conventional practitioners of modern design and construction, find it easier to develop buildings in a vacuum-as if nature, place and context do not exist. Most of today’s architectural expressions demonstrate human dominance over nature. Inefficient and overuse of limited natural resources is evidently rampant. On the other hand, sustainability demands restraint over use of natural resources. Sustainability in the sector of building design is a complex concept of multidisciplinary character. Its realization requires an integrated design approach involving all key stakeholders in the process of designing, planning and constructing buildings.

The architect, landscape engineer, owner, user, electrical, mechanical, plumbing engineers and energy professionals need to work hand-in-hand to evolve a sustainable design that allows leaving a minimum environmental footprint and yet does not forego any of the modern-day comfort requirements of human beings. The basic principles of sustainable design or ‘green design’ as it is popularly known, are to aim for maximum resource conservation, to enhance efficient utilization of non-renewable resources by adopting efficient systems, and to maximize use of renewable forms of energy as well as to re cycle and reuse resources. These principles need to be applied throughout the building life-cycle e.g. during the site planning and development stage, building planning and construction, and building operation and maintenance.

Through this article, I attempt to analyze the causative reasons behind un-sustainable design, during different stages of the building life-cycle, and to measure ways and means to address these concerns. The first section of the article addresses the site planning and design phase of a building. A subsequent article shall cover the design intervention require in building planning and construction stages to save energy, water and other material resources. Health and well-being of a building’s occupants are two other important aspects in green buildings, which would also be addressed subsequently.

About TERI

TERI is a dynamic and flexible organization with a global vision and a local focus, TERI was established in 1974. As an organization, it is deeply committed to every aspect of sustainable development. From providing environment-friendly solutions to rural energy; from tackling global climate change issue to enhancing forest conservation efforts among local communities; from advancing solutions to growing urban transport & air pollution problems to promoting energy efficiency in the Indian industry, the emphasis has always been on finding innovative solutions to make the world a better to live in.

However, while TERI’s vision is global, its roots are firmly entrenched in the Indian soil. Today, it operates out of its regional centre’s in Mumbai, Bangalore, Goa, Guwahati and Mukteshwar-and has presence in Japan and Malaysia. It has also setup affiliate institutes in Washington DC, USA as TERI-NA and in London, UK as TERI-Europe.

While in its initial period, TERI’s focus was mainly on documentation and information dissemination activities; research activities in the field of energy, environment, and sustainable development were initiated towards the end of 1982. Since then, TERI has developed and implemented various projects on sustainable and energy efficient building designs and concepts.
TERI has successfully completed various projects in design and implementation of energy efficient technologies and systems for clients like IIT Kanpur, NTPC, ITC, CII and several other private and government organizations. For the past five years, TERI has also organized the annual Delhi Sustainable Development Summit (DSDS), which is swiftly gathering momentum as a major forum for the convergence of globally renowned leaders and thinkers dealing with the issue of sustainability.

Site Planning and Design

Development of a site for building purposes requires disruption and disturbance of existing natural systems. The most sustainable and environment sensitive development is one that requires very minimal site disturbance. Resource conservation measures pertaining to site planning should entail minimum disturbance and depletion. Some recommended measures to achieve efficient site planning are given below:

Preserve and protect vegetation and soil from degradation during construction

Preservation and protection of existing vegetation, particularly mature trees, is highly recommended. This is done by avoiding cut and fills in the root zones, delineating and fencing the drip line of all trees or a group of trees. Trees should also protect against damages from carving, nailing, fires or heat emitting construction activity. The top soil, in most cases, is the most nutrient rich layer that supports vegetative growth. Topsoil removal and preservation should be mandatory for projects with site area greater than 10,000 sqm. The preserved topsoil should to be re-laid for vegetative growth through a suitable process, after ensuring its nutrient contents as per laid out codes and standards. Suitable measures such as contour trenching, mulching to prevent soil erosion and run-off should also be taken.

On the design front, the site planning should reflect design strategies that promote use of green belts and protected wetland to establish an innate network of native habitats, and to support flexible spaces integrated with the landscape for community gathering or informal activities.

Reduce hard paving

Hard paved parking lots, pathways, plazas and courts should be minimized. Hard paved areas enhance imperviousness of the sit and generate a heat island effect, which causes a sharp microclimate temperature rise. By reducing perviousness of the site, hard paving also lowers the localized aquifer recharge potential. Dark colored and constructed surfaces absorb solar energy and radiate it back when the ambience is cooler. So, typically one find a sharp temperature rise in built urban areas than in green areas. Thus, design strategies should look at a combination of soft and hard landscape, use of pervious paving, use of light colored surfaces with higher solar reflective index, shaded hard paved surfaces. Planting trees and bushes adequately also help to minimize the heat island effect.

Use more native / indigenous species in the landscape

In the current design paradigm, architectural projects-particularly large residential projects, boast of extensive green cover. In effect we get to see expansive lawns, which symbolize the ‘green spaces’. Little do the largest water consumers in any landscape. Lawns needed as much as 40%-60% more water as compared to native/ indigenous plant species or trees. Native species protect the nutrients in the biomass, promote eco-diversity, and require less maintenance and water as compare to exotic species. Because of their ability to adapt to local conditions, the native communities slow down the depletion of natural resources while maintaining the character of regional landscape. Diverse communities with varying ages and characteristics – such as trees, shrubs, vines and perennials should be planted – and monocultures and invasive species should be avoided. In addition, water requirement for landscaping should be controlled thorough adoption of efficient irrigation practices e.g.  drip irrigation.

Enhance site lighting efficiency and avoid light trespass / light pollution

Site lighting is mainly used to illuminate connections between buildings and support facilities such as sidewalks, parking lots, roads, community gathering spaces, landscaped areas and for security purposes.  It must be carefully designed to avoid waste and nuisance. It must address a few basic standards such as- it should avoid over luminance; it should be properly shielded to avoid light pollution; the optical control of light is also critical. Light pollution can be defined as waste light emanating from building sites that produces glare and adversely affects the environment. Waste light does not contribute to increased night time safety, utility or security and needlessly consumes energy. Light pollution can also potentially disrupt biological cycles in plants and animals, including humans.

Recommended Practices

  • Restrict area and time for night time illumination-minimize areas on site that need to be illuminated all night. For security lighting, motion-sensors may serve the purpose, in place of constant lighting.
  • Clearly identify the actual purpose of lighting to determine minimum acceptable levels- safety and security lighting is an important part of exterior lighting. Layered lighting provides minimal ambient illumination with accents on hazards, destinations and architectural features.
  • Use energy-efficient lamps and ballasts- The most efficient new lamps produce ten times as many lumens per watt of power as a conventional incandescent bulb. Savings on operating-cost and labor, including deferred bulb replacement quickly recover the cost of re-lamping. Technologies to reduce light pollution include full cut-off luminaries, low reflectance surfaces, and low-angle spotlights.
  • Use of appropriate control strategies- simple timers of photocells can be used to turn lights on and off at appropriate times.
  • Use renewable energy sources for lighting and other outdoor power- Photovoltaic power is low-maintenance and very reliable. Its design must be specific to both the region and the site. It requires storage batteries for night time lighting. Manufacturers also offer solar path lights, steer lights, and security lights. Low voltage lighting with photovoltaic collectors should be considered for energy – efficient alternative.

Energy Efficiency in Green Buildings

One of the primary requirements of a green building is that it should have optimum energy performance and yet should provide the desirable thermal and visual comfort. The three fundamental strategies adopted to optimize energy performance in a building can be broadly classified into the following.

  • Incorporate solar passive techniques in a building design, and enhance building material specifications, to minimize load on conventional systems (heating, cooling, ventilation, and lighting)

Passive systems provide thermal and visual comfort by using natural energy sources and sinks e.g. solar radiation, outside air, sky, wet surfaces, vegetation, internal gains, etc. India has six climatic zones ranging from extreme conditions in the cold regions of Leh and Ladakh to extreme hot & dry conditions in Rajasthan. A building in a cold climate zone needs to adopt measures to maximize its solar heat gains by embracing measures like maximum exposure to the south, windows to capture heat, dark colored surfaces, high thermal mass and insulation, to retain the captured warmth of the sun OR use of design elements such as thrombi wall, sun spaces etc.

On the other hand, a building designed for a hot climate should take measures to reduce solar gain like, smaller window sizes, shaded walls, minimum exposure to the west and east. OR use of design elements like solar chimneys, wind towers, etc to maximize ventilation. Use of building materials like energy efficient glass, e.g. insulated double glass units with solar control coatings can reduce heating / cooling demand by 8-10%.

To state an example – the TERI Retreat Building at Gurgaon (a residential training complex of TERI) built in the composite climate of Delhi, employs several passive techniques to cut down its energy demand for heating, cooling and lighting. Building insulation and glare free daylight are only some of these features. Part of the building is partially sunk into the ground in order to take advantage of ground storage- and thus stabilize internal temperatures. Shading devices and fenestration have been designed to cut off summer sun and to let in winter sun. Landscaping favorably alters wind directions. Deciduous trees used in the south side of building shade the building during the summer. During winters, the trees shed their leaves to let in the winter sun.

Space conditioning of a part of the building happens through a network of underground air tunnels laid at a certain depth below ground. These earth-air tunnels stabilize internal temperatures. A solar chimney with a flat plate collector on top creates a draft and exit for hot air on the south-side rooms.

On the other hand, The TERI Conference Complex located in the hills of Uttaranchal-which is predominantly cold and cloudy- has incorporated passive techniques to allow maximum solar gain and to retain warmth in the spaces. The orientation of the building is south and southeast. Trees have been strategically planted on the northern side to buffer against cold winds, while the southern face is left exposed for maximizing energy gain from the sun. Insulation using fiberglass panels in the ceilings and walls preserve heat and absorb sound as well.

To cite another example, TERI’s Southern Regional Centre-in the moderate climate of Bangalore, has effectively used passive solar energy for enhancing comfort, and to negate adverse site impacts. The site posed a challenge with primary wind movement being from south to north, and the presence of a foul smelling nallah flowing along the southern boundary of the site. Constraint resulted in a built form to deflect the foul winds and yet ensure ventilation adequacy.

A black absorption double-wall with Cuddapah stone cladding, was built in the south to offset the negative impact of the site. The sun’s rays, heat, and the black south wall increasing the temperature of the immediate environment around (in this case being the air within the cavity). This convectional means These convectional currents are pulled away by the natural winds blowing south to north. This creates a vacuum at the top core of the structure.

To fill this vacuum air from inside is drawn up which is again pulled up by the moving convectional currents. This system of rising of hot air and drawing in of cool fresh air is a continuous process. Hence, reverse wind circulation is established by bringing in the cool fresh air from the north open face of the building and drawing it through the entire section of the structure, and removing it by convectional means up through solar wind vents. Thus, sun energy is used effectively to enhance ventilation (for better comfort levels) and deflect unwanted wind flow. It was an added advantage for day lighting as the design form evolved to maximize northern exposure. By creating atrium spaces with skylights, it is designed in such a way that natural light enters the heart of the building, considerably reducing the dependence on artificial lighting. Energy efficient lighting like efficient lamps, luminaries and control strategies further reduces lighting loads on the building.

  • Design energy-efficient lighting and HVAC systems (heating, ventilation and air-conditioning)

Once the passive solar architectural concepts are applied to a design, the load on conventional systems (HVAC and lighting) is greatly reduced. Further, energy conservation is possible by efficient design of the artificial lighting and HVAC system using energy efficient equipments, controls and operation strategies.

TERI’s experience in the CII-Godrej Green Business Centre (GBC) in Ahmadabad, shows about 35% energy saving was achieved by efficient lighting and HVAC systems. The building has received the prestigious Platinum rating by the United States Green Building Council (USGBC). The lighting power density of the proposed building was reduced by use of efficient lamps- compact florescent lamps, high efficiency tube lights, luminaries and ballasts. Further, the building being fully day lit, huge savings result by use of day linking strategies. The contribution of lighting energy savings in the overall, improved energy performance of the GBC building by 15%.

The improved HVAC system efficiency contributed to another 20% energy savings. Energy conservation measures in the HVAC system including use of efficient water-cooled chillers with high COP, variable air volume systems, efficient cooling towers, primary/secondary chilled water pumping systems, and suitable control strategies. Wind catchers designed as evaporative pre-coolers were designed for pre-cooling of fresh air input into the air handling units of the HVAC system.

  • Use renewable energy systems (Solar photovoltaic systems / solar water heating systems) to meet a part of the building load

The pressure on the earth’s non renewable resources can be eased by effective use of the earth’s renewable resources e.g. solar, geothermal, wind and biomass energy. The Retreat Complex of TERI has used a judicious combination of biomass and solar energy to meet all its energy requirements. The CII –Godrej Green Business Centre has a 23 kWp roof integrated solar photovoltaic system to meet nearly 20% of the building’s energy requirements for lighting and air conditioning.

  • Use low energy materials and methods of construction, and reduce transportation energy.

An architect should also aim at efficient structural design, reduction of use of high energy building material such as glass, steel etc. and reducing transportation energy. Use of environmentally sensitive construction materials and techniques reduce embodied energy content of buildings. Some common products are –use of flyash in building materials e.g. use of blended cement for structural systems; use of flyash based bricks and blocks etc; use of ferrocement and precast components for columns, beams, slabs, staircase, lofts, balconies, roofs etc; use of wood substitutes for doors/windows/cabinet frames and shutters.

Conclusion

Energy saving of up to 60% are achievable if buildings are designed using green design principles. The final selection of the design measures should be done after doing a cost benefit analysis of the same. Typically, the measures described have a payback period between 1-3 years. In the current perspective of increasing energy demand for powering the energy intensive systems in a building, time has come when, green design should not be an isolated effort by an inspired individual, but a standard design process which is adopted in all our future buildings.

Reference:
Vol: 48 No. 6
June2008

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