Friday, June 14, 2013

Kolkata highrises to get rooftop solar panels

Kolkata highrises to get rooftop solar panels

Author(s): Sayantan Bera
Date:Jun 13, 2013

The Calcutta High Court in a judgement on June 11, ordered civic authorities to ensure all highrises in the city of Kolkata have rooftop solar panels installed within the next four months. The judgement came in response to a public interest petition filed by environment activist Subhas Dutta in 2009.

‘West Bengal meets 97 per cent of its power requirement from coal, much higher than the 64 per cent for India. To meet our emission targets by 2020, we need to reduce our dependence on thermal power and bank on renewable sources,’ says Dutta. ‘The building rules of the Kolkata Municipal Corporation (KMC) specify that any highrise over 15.5 metre (five storeys) in height needs to install rooftop solar panels. For other municipalities in West Bengal the cut-off is 14.5 metre (four storeys). The High Court order will finally move things in the right direction,’ he adds.

Ten per cent from renewable sources

The bench consisting of Chief Justice Arun Mishra and Justice Joymalya Bagchi also instructed power utilities in West Bengal to meet their renewable energy obligations to purchase or generate 10 percent of power supplied through renewable sources. This has to be ensured by the West Bengal Electricity Regulatory Commission. At present, power utilities in the state source less than 0.5 percent of their energy supply through renewables, says Dutta. The court has asked the state to look into how to reduce direct or indirect taxes on solar panels.

‘The challenge is to get the power utilities and builders interested. To store the power generated via rooftop panels in batteries might be impractical; it is necessary to connect the solar power generation system to the grid. Therefore we need to change the power metering devices,’ says Himadri Guha, former professor of civil engineering at Jadavpur University and now a developer himself. Kolkata has only once such equipped housing complex, Rabi Rashmi in New Town, says Guha.

Comment by Anumakonda Jagadeesh

It is a welcome measure.

Much of the current in the country is wasted in Air conditioning especially in the Government offices which is a waste of public money. Can't ways and means be found to reduce this? One is to fit alternate fans in the AC Rooms(which are not there in some cases) so that in Winter less use of Air conditiones is there. Also All Government buildings to be built should have plan in such a way they consume less power with provision of cross ventilation. Also most of the Government offices inside have dark colours which reduce light intensity from lights. In many cases there will be venesian blinds for the room and room is lit by lights during daytime also(including afternoon ).

In this connection traditional housing practices in Rajasthan need to be studied and modified with latest technology. Old houses in Rajasthan are cooler in Summer and warmer in winter.

Power should be seen as a NATIONAL ASSET. By simple energy conservation measures enormous power can be saved. For example: we have around 1 lakh irrigation pumpsets which in many cases are obsolete. They are inefficient systems. The Government can chalk out a scheme to replace the old irrigation pumpsets with efficient ones by providing subsidy. Electricity is a high grade energy. In many cases the tariff for Agriculture power is low or nil. As such the Farmers won't take care to properly use the electric motors.

“The impact of air conditioning on office buildings has had two major effects. First, is the opportunity to design and construct buildings without the constraints of passive measures to maintain cool comfort. The second was the opportunity to introduce new materials and construction techniques in the (sometimes uncertain) knowledge that air conditioning will maintain a comfortable environment. The outer shells of buildings provide the primary barrier between the internal and external environments. The environmental
systems compensate for the inadequacies or otherwise of the barrier. It is now difficult to distinguish whether poor curtain walls created an adverse view of air conditioning in the 1950s and 60s or whether the fault lay with inadequate air-conditioning systems. The current cladding systems that evolved from these experiments now provide the level of isolation from the outside climate only aspired to by Le Corbusier. The downside of this technology is that it is cheaper to build lightweight buildings and seal them with cladding than to provide passive means of control such as exposed mass and operable windows. This means buildings will most probably remain air conditioned for their life irrespective of whether or not cooling can be provided by natural means and the impact of full air conditioning on the environment.

The application of this type of .air and water. terminal unit method of air conditioning was another important advance.The air and water induction unit air-conditioning system had three main advantages over the all-air systems at the time: . Most heat gain and loss from the building is through the window and the under-sill location of the units compensates with minimal effect on the room condition.. Heating and cooling energy is transported around the building by water,a much more efficient medium than earlier systems that used air. . Considerably less vertical duct space is required, as the main supply ducts operate at high velocity and only handle enough air to meet the minimum fresh air ventilation requirements.

The United Nations Building in New York was the first major international building to be constructed after the war.A multinational advisory committee was established for the design of the building.It was composed of a number of leading architects, including Le Corbusier.The director of planning and lead architect was Wallace K. Harrison who helped design tall buildings such as Rockerfeller Center before the war. During the development of the scheme, Harrison was involved in a number of conflicts with Le Corbusier, who allegedly claimed credit for the design concept. One such argument involved protection of the offices in the Secretariat (Tower) Building against excessive solar heat gain and glare. Le Corbusier had preferred stone facades but the board preferred to maximize sun and natural daylight using overall glazing. They decided this could be achieved best with curtain walling, even though at the time it was an unusual solution for a skyscraper.The Equitable Building was the only example of a continuous glazed curtain wall in the country and .even in those energy rich days this much glass raised the question of heat gain and loss.. They considered four different glazing options in conjunction with internal venetian blinds.These included single and double-glazing
with and without tinted glass(Source: Air Conditioning in Office Buildings After World War II,ASHRAE Journal David Arnold,July 1999)”.

“Catherine Wolfram, co-director of the Energy Institute at Haas School of Business, University of California, Berkeley, points to data showing that the increase in energy demand between the hottest and coldest months of the year among the 16 million residents of Delhi, India, more than doubled between 2000 and 2009. In a 2012 essay on this research she concluded, “A large part of the explanation for this is that air conditioner sales have increased dramatically.”

The developing world is home to most of the world’s hottest and fastest-growing cities—38 of the world’s 50 largest cities are in developing countries, and most of the 30 warmest of these cities are in developing countries. These countries also have a rapidly expanding middle class that can now afford the amenities that citizens in the developed world have long taken for granted. High on that list is the air conditioner.

India and other nations in South Asia and Southeast Asia are on track to record the world’s biggest increases in demand for air conditioning. Sales of air conditioners in India rose an estimated 17% over the past three years, with sales rising fastest among residential users. Michael Sivak, a research professor at the University of Michigan, estimated the potential demand for cooling in Mumbai alone at about 24% of the entire U.S. demand.

Mohammad Arif Kamal, an assistant architecture professor at Aligarh Muslim University, explains that air conditioning has become de rigueur in India. “Air conditioning has become a social and status symbol,” he says. “People are discarding their old, traditional homes made of bricks, mud, adobe, timber, bamboo, etc., in exchange for boxes made of concrete and glass in pursuit of modernization, which consumes a lot of operational energy.”

Michael A. McNeil, a researcher at the Lawrence Berkeley National Laboratory, has looked at global air-conditioning use and found that air-conditioner ownership in warm-climate countries grows more rapidly than does economic growth. And if China is any example, he contended in a 2008 article, the adoption of air conditioning in developing countries could be rapid and vast: In 1990, fewer than 1% of Chinese households owned air conditioners, but by 2003, he reported, that number had increased to 62%.

In addition to placing strains on nations’ power grids, air conditioners pose threats to the environment and environmental health, primarily as contributors to global warming. “The amount of electricity that’s used for air conditioning is a huge part of an energy load for most countries, and it’s going up,” says Durwood Zaelke, president of the nonprofit Institute for Governance and Sustainable Development. “You’re putting out more climate pollutants as you’re burning more coal or gas to run the air conditioners, and you’re also putting out the greenhouse gases that serve as the refrigerants in the equipment.”

According to Cox, approximately 80% of the impact of air conditioning on climate results from the draw on fossil fuel–fired power plants. The remaining 20% comes from the units’ refrigerants, the liquid agents within the coils that are used to cool and dehumidify the air.

Meanwhile, engineers are building more efficient air conditioners that draw less heavily on power supplies. For many years the Japanese government has pursued a number of measures to reduce electrical demand, including an initiative called the Top Runner Program. The program sets efficiency standards for electrical products, including air conditioners, by identifying the most efficient ones being produced and establishing that performance level as the new baseline that other manufacturers must match.

Although air-conditioning use will certainly continue to increase globally with no serious regulatory frameworks in sight, some observers believe awareness of its environmental impact is beginning to change the ways in which architects and engineers, at least, are approaching the challenge of keeping people cool. In fact, many planned and existing buildings employ a variety of technologies—new and old—to achieve comfortable indoor temperatures without resorting to the use of air conditioners.

Pablo LaRoche, a professor of architecture at California State Polytechnic University Pomona who also practices in the Los Angeles firm HMC Architects, believes the true solution for temperature management is passive cooling systems. Such a system transfers heat from a building to any combination of exterior heat sinks—such as the air, water, and earth—through special design details in the building itself. By providing pathways to carry heat from the interior of the building to the outdoors, he explains, the building itself becomes the air conditioner, using little or no energy at all.

LaRoche points out that different types of passive cooling systems work better in different climates. For example, he says evaporative cooling (which adds moisture to the air) works best when the air is dryer, whereas night flushing (using cold night air to ventilate a building and cool its thermal mass) is preferable for places where there is a greater temperature difference between daytime and nighttime temperatures.
Passive downdraft evaporative cooling (PDEC) employs the spraying of microscopic water droplets into the air, a concept borrowed from traditional architecture in Pakistan, Iran, Turkey, and Egypt, according to Kamal. These traditional buildings were topped by wind-catching hoods (malqafs) that pulled air down chimneys and cooled it by directing it across a source of moisture: a pool, a fountain, or porous pots that seeped water. Contemporary PDEC buildings also employ wind catchers but replace the water pots with wet cellulose pads or similar devices. Kamal cites the Torrent Research Centre in Ahmedabad, India, as an excellent example of contemporary use of PDEC. The center was completed in 1999 and has reportedly provided comfortable conditions for occupants while also recording extremely low energy consumption.
Another example of a hot-climate structure using water and traditional design for cooling is Pearl Academy in Jaipur, India. The building includes a sunken courtyard pool, which architect Manit Rastogi explains functions similarly to a basement, staying cooler than the aboveground air in the summer and warmer in the winter; breezes flowing under the raised building create evaporative cooling currents that push air up through atria and open stairwells.

The building also features an exterior latticed screen ( jaali ) enveloping the building, a traditional feature of Rajasthani architecture that provides a thermal buffer for buildings (however, this is not considered true passive cooling, but rather a strategy to avoid overheating). Despite the fact that the building is located in a hot desert climate, Rastogi says it maintains interior temperatures of 80–85°F even when it’s 110°F outside, using minimal mechanical air conditioning just two months of the year.

Pearl Academy in Jaipur, India, features a sunken pool, inspired by traditional Rajasthani architecture, that takes advantage of the thermal-regulating properties of the ground.

One of the most unusual and innovative examples of a structure utilizing traditional technology might be architect Mick Pearce’s Eastgate Centre, a shopping center in Harare, Zimbabwe, that was inspired by a 1992 BBC television program on termites, hosted by naturalist David Attenborough. Pearce was struck by the termites’ use of the thermal capacity of the ground and the mound, and their labyrinths of ventilation tunnels. “The termite mound which we see above ground is a breathing and air-conditioning system like the human lung,” he says.

Eastgate Centre relies on night flushing: Cool night air is driven through a multitude of air passages within the building’s heavy concrete and masonry structure, cooling the concrete vaulted ceiling, which absorbs heat during the day. The accumulated heat from each day is vented at night through these same passages, partly by fans and partly by convection forces in 48 huge stacks that run through the center of the building”(Cooling Concepts: Alternatives to Air Conditioning for a Warm World,Environmental Health Perspectives, Richard Dahl).

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