Edu-leaders

Across the world, with concerns for environment dominating the collective psyche, green campuses have become the byword. Institutions everywhere are taking the lead in going natural to cut down on carbon footprints. Green cooling is among the concepts adopted by campuses to beat the summer heat without carbon-emitting air-conditioners.

Green concepts dominate the planning stage itself. Thinking about green cooling during the design process provides opportunities to incorporate some of the basic principles of sustainable design, including passive cooling.

Be it earth-air tunnels, shaded angled apertures, displacement ventilation or natural insulation techniques, architects and designers are advocating the use of natural methods to keep the heat out of buildings. The shift to building ideas based on considerations like sun orientation, day lighting and shading has led to functional buildings where energy-efficient practices have brought down electricity bills. Apart from ensuring energy conservation, green methodologies offer benefits such as increased access to daylight and fresh air. On a campus, such environment-friendly architecture principles help nurture healthy attitudes and let the next generation perfect the green language. Some cool campuses have paved the way for design innovations in architecture using traditional methods.

Life is a Breeze
The Centre for Environmental Planning and Technology (CEPT) is a cool campus. Students here are a chilled lot — without an air-conditioner. No sweat, what if the country is reeling under the sweltering temperatures? For students here, keeping cool is a breeze.

CEPT is an architectural marvel where traditional systems of cooling have been successfully blended in the natural design and architecture plan. Architect B.V. Doshi, who compares his structure to a “functional factory building”, says: “Apart from deep shaded angled apertures set in the wall to keep the glare and heat out, we decided on a north-south orientation of parallel bays for better air flow and to diminish the impact of the sun.” He adds that the height of spaces was planned according to activity requirements, for example double-height airy interiors to be used as drawing studios and single-height ones for discussion groups or classrooms.” The utilisation of open spaces in CEPT is again worth emulating. The Centre has a series of walkways, a combination of steps and platforms, which serve as interlocking common spaces for informal gatherings. The building has been raised on pilotis (piers) and the shaded areas underneath work as multifunctional spaces where classes, indoor games and competitions are held in the natural breeze. As a result these areas are well-used at times when campus activities in other institutions see a decline.

Borrowing from Tradition
At NIIT University, Neemrana, the designers, Space Design Consultants, and master planners, YRM London, turned to an age-old building technique to keep the interiors cool. The university showcases the use of earth-air tunnels — a low-energy cooling system that works on the principle that the temperature recorded at about 4m below the surface is around 10-12 degrees lower than the temperature on the ground. In this system, which uses only 30% of the energy of a normal air-conditioning system, fresh air is drawn through an underground duct (the “earth-air tunnel”) laid 4m down.

Heat exchange with the underground duct cools down the air, which is then treated for temperature, humidity and dust, and supplied to the building. Later, the air is expelled through a chimney. The system produces 100% fresh air and maintains a healthy environment inside.

Speaking about the system, Kamal Singh, Infrastructure Advisor, NIIT University, says, “Air is sucked through a tower — that adds to the architectural signature of the design — and is released at the other end, which opens out into the building. Along the way, the temperature is brought down about 10-15 degrees.”

The passive solar control measures allow the buildings to be well-lit and free of dust, while the up-and-down ventilation through vertical shafts averts the need for windows for ventilation. Skylights and light shelves (horizontal light-reflecting overhangs placed above eye-level and with a high-reflectivity upper surface to bounce daylight onto the ceiling and deeper into a room) and skylights are used to conserve energy through day lighting. All buildings are oriented in a north-south direction so have minimal exposure to the hot western sun. The use of glass on exteriors is limited and, whenever used, the glazing is shaded from the sun.

“The buildings, built with a high percentage of recycled materials, are insulated from outside and detailed to avoid thermal bridges. They are designed to be cool and dust-free,”Singh elaborates.

Dig up the Tunnels
At TERI University, earth-air tunnels are employed to keep temperatures down in the hostel block. The orientation of building blocks and spaces ensures glare-free daylight in regularly occupied areas. The east, west and south facades of the building have minimum glazing and the form of the building casts a shadow on the glazing, blocking direct sunlight. The use of insulating material on walls and roofs, and high-performance window glazing that minimises thermal gain, enhances energy efficiency. The lighting system is designed to minimise energy consumption and takes advantage of day lighting.

Rajiv Chhibber of TERI University says green design features contribute about 40% in energy savings compared to conventional buildings. He adds the rationale is that “the campus has been planned to provide a setting that enhances learning and showcases the concept of modern green buildings.”

Wind Towers for Natural Ventilation
Passive cooling is also possible through the process of displacement ventilation, an idea that has been around for years. This process allows buildings to be ventilated by letting in cool air and letting out warm air. In practice, designers can provide openings at low levels to bring in cooler air and high openings (such as clerestory windows — windows that rise above adjoining rooflines) to let out the rising warm air, so as to create a natural flow of air.

The University of Jodhpur, also designed by Space Design Consultants, provides thermal comfort by using displacement ventilation to keep the rooms cool. Here, a wind tower with an evaporative cooling system and small exhaust ducts is used to bring cool breeze into all rooms of the building. Massive stone walls, made from locally procured stone, shade windows and insulate roofs, and also add a pleasant ambience in the peak of summer.

Sun Blocked
At NIFT, Hyderabad, architecture has been used innovatively to keep out hot air. The design is such that the central court remains shaded most of the time, making outdoor activity possible.

Blank walls lined with lockers run along the main internal circulation spine on the south-west side. The walls work as an insulating layer and keep solar radiation and heat out.

Sonali Rastogi, co-founder of award-winning architectural practice, Morphogenesis, is responsible for the low-cost, environmentally sensitive campus, Pearl Academy of Fashion in Jaipur. After intensive solar and thermal analysis, the building was conceptualised based on the baoli, or stepwell, of ancient Indian architecture.

The structure is raised over the ground, creating a scooped out underbelly that forms the “sink” for the water body. Recycled water helps maintain the microclimate through evaporative cooling and reduces dependence on mechanical environmental control measures. “The building casts a long shadow on the water body, so it doesn’t heat up. To ensure that it’s sustainable, the water is recirculated. The structure is wrapped in a jali (screen) and water is dripped onto the jalis, bringing down the temperature,” Rastogi explains.

Since this was a low-budget project, Rastogi also turned to a cost-effective Rajasthani insulating technique. “We put inverted matkas on the roof; this keeps the temperature down and reduces the need for air-conditioning significantly,” she says.

The passive environment design reportedly helps achieve temperatures of about 27˚C inside even when the temperature outside is touching 50˚C.

Solar heat and radiation are also absorbed through windows and roofs. Plantation cover and landscaping shading concepts help reduce the solar heat gain and bring down costs. Shading and evapo-transpiration (the process by which a plant actively moves and releases water vapour) reduce surrounding air temperatures by 5˚C to 6˚C. The temperature directly under trees could be as much as 15˚C cooler as cool air settles near the ground. Planting trees of appropriate sizes, densities and shapes can help throw shade on windows and openings, blocking the sun’s rays. Adding perennials and vines that cluster on walls also helps.

Old is Cold Too
New campuses can plan to be green starting with the first building block itself, that is, at the design stage. But, for old campuses, designers need to take into account existing constraints and aim to maximise the energy efficiency of mechanical cooling systems and not just incorporate new concepts into the design. An open floor plan allows optimisation of passive solar cooling. Improvements to the building envelope — sunshading, insulation, thermal bridging and high-performance glass — can optimise the design.

Since the positioning of openings can’t be changed, experts suggest fitting windows with double-glass panes where the insulating air space between the panes reduces heat transfer. Placing direct shading devices such as pergolas and solar screens at appropriate places can also enhance energy efficiency. For shading roofs, one can use fixed shades of light-weight materials, movable shades of canvas, or landscaping elements. However, experts say keeping windows shaded is more important since glass permits sunlight to enter the building but does not allow long-wave heat radiated by room surfaces to escape. Deep overhangs or solar screens can be used to shield glazed areas from direct sun rays and avoid excessive heat gain. When it comes to sun control, low e-glazing can also help, especially on the western side of buildings.

The importance of landscape shading elements rises manifold in existing campuses — trees, vines and vegetation cast shade and reduce the effect of solar gain. Awnings can also reduce heat gain by as much as by 65% on windows with southern exposure and by 77% on those with western exposure.

Daylight harvesting, a lighting strategy designed to minimise energy consumption and lower bills, takes advantage of day lighting wherever available. Light shelves and skylights can help in this endeavour. Switching to energy-efficient compact fluorescents can also help lower temperature as about 80% of the energy consumed by incandescent lighting is wasted through heat.

Rastogi says, “If the basic orientation of the building vis-à-vis the sun is wrong, there’s not much that you can do about it. After all, any building that faces the west is a killer. Otherwise, one can adopt simple solutions like jalis, second skins and shades to bring down the temperature.” She also advocates the use of water bodies to keep the atmosphere cool.

A Wise Investment
Considerable R&D shows the cost of building green is higher than conventional building. The major cost contributors are energy-related systems: the building envelope, lighting, electrical and HVAC (heating, ventilating and air-conditioning). A study, Costing Green: A Comprehensive Cost Database and Budgeting Methodology, reveals integrating green features into a project early is critical. “The choices made during design ultimately determine whether a building can be sustainable, not the budget set,” says the report by Davis Langdon Adamson, a construction cost-planning company. Though initial costs may be higher than conventionally designed buildings, the savings — be it on energy, water, maintenance, operations or health costs — justify expenditure. The Costs and Financial Benefits of Green Buildings report by the Massachusetts Technology Collaborative for the California Sustainable Building Task Force says, “While the environmental and human health benefits of green building have been widely recognised...minimal increases in upfront costs of about 2% to support green design would, on an average, result in lifecycle savings of 20% of total construction costs — more than 10 times the initial investment.”

It is estimated that going green in India costs approximately 10% more. “But this incremental cost, when compared to the lifecycle cost of the building, is small. There are extensive savings when one looks at the lifecycle of the building,” Rastogi says.