Thursday, September 19, 2013

passive cooling

in rajasthan, india - outdoor temperatures hit 45 c in the summer. ancient indian architecture turned to an elegant solution to keep buildings cool - the baoli - the hindi word for stepwell - they are bodies of water encased by a descending set of steps.

this cnn report highlights a new building by the architect manit rastogi who has designed the pearl academy of fashion in jaipur:

"When water evaporates in heat, it immediately brings down the temperature of the space around it," he says.

While traditional stepwells often go many stories below ground level, Rastogi's go down just four meters. However, the effect is the same and -- like the ancient Mughal palaces before it -- the academy enjoys its own microclimate.

in the heat of the rajasthan summer, the academy maintains a temperature that is 20 degrees lower than the outside because of the baoli indoors and the application of some other ancient ideas:

It's not just the stepwells that are involved in this process of "passive cooling" -- the general term applied to technologies or design features that cool buildings without power consumption.

The whole building is raised above the ground on pillars, creating an airy and shaded pavilion that is used as a recreation and exhibition space. Here, according to Rastogi, the walls are made from a heat-absorbing material that creates a "thermal bank" -- so the warmth is slowly released at night when the temperature drops.

Centuries ago, latticed screens or "jaali" filtered direct sunlight into the palaces. The effect was decorative and helped reduce the heat. Likewise at The Pearl Academy, a latticed concrete screen runs the length of the building and provides a cooling outer skin.

"We've been able to demonstrate that good green building is not only cheaper to run; it's not only more comfortable to live in -- it's also cheaper to build," says Rastogi.

an external view of the pearl academy:

these passive cooling techniques have been introduced in all indian government buildings.

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