Saturday 15 September 2012

Author(s): Anumita Roychowdhury

  • Anumita Roychowdhury, Thanks

    Anumita Roychowdhury, Thanks for a great article. You have provided both breadth and depth in an important area. ÔÇ£Green building is common sense that blends traditional wisdom with modern science.ÔÇØ So true. It reminds me of what a professor told me at a theological seminary many yrs ago: ÔÇ£Wisdom is to Take the Best of the Old and Combine it with the Best of the NewÔÇØ Good to see India rising to the challenge of man-made global warming.

    Posted by: Anonymous | 3 years ago | Reply
  • Excellent article. It is an

    Excellent article. It is an irony that in India in most places we first heat the buildings and begin to cool it by Air cionditioners and Fans. In the traditional house construction the entrances used to be face to face so that there is cross ventilation which helps for natural cooling. Indigenous architecture has evolved suitable building styles for severe climates. It may now be added that traditional urban design provided the appropriate environment without which even the best building design could not have been wholly successful. JAISALMER (Rajastan ): The best example of architecture of the hot and arid zone in India is Jaisalmer, a town built in the heart of the Thar desert. The geographical location of Jaisalmer is 26 deg. 55 min. North (lat.) and 70 deg. 55 min (long.), with a height above mean sea level of 241.66 meters. The day time temperatures in June reach up to 50 deg. C while the night temperatures in January are below the freezing point. Annual rainfall during the year is 120 to 150 mm, but in some years there is no rainfall at all. During the summer months of May, June and July, the town is subjected to severe sand storms. The climate demands protection from the scorching summer sun and sand storms on the one hand and very cold winter nights on the other. Humidity being low throughout the year, comfort could be easily provided by evaporative cooling, but this is not possible because water is very scarce in Jaisalmer. The only sources of water are the very deep wells and the Gharhisar tank on the outskirts of the town. The layout of the town is the first defense against the harsh climate. The streets are narrow and shaded from the sun. The general street orientation is south east to north west, which is at right angles to the prevailing summer winds. Hot dusty winds are thus kept out of the streets. At many places, buildings overhang the streets on both sides, providing a cool shaded area almost like a tunnel. In some places the buildings actually bridge across the streets. The contiguous construction ensures mutual shading by walls and other elements of the adjoining building. The main building material used for walls is light yellow coloured sand stone. Roofs are built of mud, supported on wooden beams covered with grass mat. In more recent construction, stone beams have been used as roof supports. The thickness of the roof varies from 45cms. to 90 cms., enough to dampen the effect of the diurnal temperature variations. There is no scientific study to compare the performance of the two kinds of roofing (i.e. stone slabs and wooden beams), but according to popular belief the wooden ceilings with grass mats stay cooler than stone ceilings. The wall surfaces are highly articulated with projecting balconies, sun shades and brackets, and each of these building elements is in turn intricately carved. Flat portions of stone walls are also decorated with deep carvings. The resulting overall building surface is designed to stay cool even when it is exposed to the sun. According to the economic and social status of the house owners, there are three types of buildings. The poorest live in very small single storey houses built in mud. There is generally a small room and a verandah opening into a small courtyard enclosed by high walls. Usually a small basement is also built, but it is not ventilated and therefore used only as a store for valuables. The main living area of the house is the courtyard and verandah. The heavy roof and walls along with the courtyard ensure thermal comfort in the house. The middle income house is a two or three storied structure with a completely enclosed courtyard. The deep and narrow building plot of land is surrounded on three sides by similar construction and on the fourth side by the narrow street. Therefore, solar heat gain through the walls is very little. The rooms built next to the street are cross ventilated through the courtyard. This may not be possible in the rooms built in the rear of the plot. Since window openings are small and the courtyard very deep, most rooms in these houses are poorly illuminated. Architecturally the most interesting and the most comfortable thermally, are the "Havelis" (large courtyard houses) belonging to the rich. These are three or four storied structures with additional wind pavilions on the top floor. Each building is built around one or two courtyards with additional ventilation shafts provided at appropriate locations. Almost all the special thermal design features of these "Havelis" are incorporated in Nath Malji's Haveli . In the olden days most of the houses have white colour both outside and inside. Outside to reflect sunlight and inside to use less lighting(Electricity). But today it has become fashionable to have even darker colours inside the house. Another classic example of natural airconditioning is Eastgate Centre,Harare,Zimbabwe. The Eastgate Centre in Harare, Zimbabwe, typifies the best of green architecture and ecologically sensitive adaptation. The countryÔÇÖs largest office and shopping complex is an architectural marvel in its use of biomimicry principles. The mid-rise building, designed by architect Mick Pearce in conjunction with engineers at Arup Associates, has no conventional air-conditioning or heating, yet stays regulated year round with dramatically less energy consumption using design methods inspired by indigenous Zimbabwean masonry and the self-cooling mounds of African termites! Termites in Zimbabwe build gigantic mounds inside of which they farm a fungus that is their primary food source. The fungus must be kept at exactly 87 degrees F, while the temperatures outside range from 35 degrees F at night to 104 degrees F during the day. The termites achieve this remarkable feat by constantly opening and closing a series of heating and cooling vents throughout the mound over the course of the day. With a system of carefully adjusted convection currents, air is sucked in at the lower part of the mound, down into enclosures with muddy walls, and up through a channel to the peak of the termite mound. The industrious termites constantly dig new vents and plug up old ones in order to regulate the temperature. The Eastgate Centre, largely made of concrete, has a ventilation system which operates in a similar way. Outside air that is drawn in is either warmed or cooled by the building mass depending on which is hotter, the building concrete or the air. It is then vented into the buildingÔÇÖs floors and offices before exiting via chimneys at the top. The complex also consists of two buildings side by side that are separated by an open space that is covered by glass and open to the local breezes. Air is continuously drawn from this open space by fans on the first floor. It is then pushed up vertical supply sections of ducts that are located in the central spine of each of the two buildings. The fresh air replaces stale air that rises and exits through exhaust ports in the ceilings of each floor. Ultimately it enters the exhaust section of the vertical ducts before it is flushed out of the building through chimneys. The Eastgate Centre uses less than 10% of the energy of a conventional building its size. These efficiencies translate directly to the bottom line: EastgateÔÇÖs owners have saved $3.5 million alone because of an air-conditioning system that did not have to be implemented. Outside of being eco-efficient and better for the environment, these savings also trickle down to the tenants whose rents are 20 percent lower than those of occupants in the surrounding buildings. In Hindu mythology there is a saying: Well Water,Brick House and Banyan Tree Shade are warmer in Winter and cooler in Summer. Dr.A.Jagadeesh Nellore(AP),India

    Posted by: Anonymous | 2 years ago | Reply
  • Anumita and Eco

    Anumita and Eco Warriors, Nature is the best source of ideas and inspiration. Living in its harmony and emulating how it preserves and keeps the earth alive is the way forward for all of us. Excellent topic/coverage by Anumita, enjoyed all the posts. Look forward to remaining active and focused on the topic.

    Posted by: Anonymous | 8 months ago | Reply
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