Green lessons from Mughal architecture

Ancient 'air-conditioning' cools building sustainably

From Nick Glass and George Webster, CNN

March 8, 2012 -- Updated 1725 GMT (0125 HKT)

Built in the arid suburbs of Jaipur, Rajasthan, The Pearl Academy of Fashion combines 

modern exterior styling with ancient Rajasthani architecture -- designed to keep 

temperatures down without artificial cooling systems

STORY HIGHLIGHTS

·       Architect has adapted India's ancient stepwell architecture for a modern, sustainable building

·       Pools of water at base create low-tech "evaporative cooling" of surrounding area

·       Academy protected from elements by a double skin, derived from traditional "jaali" structure

Green lessons from Mughal architecture

Jaipur, India (CNN) -- How did buildings keep cool before the invention of air conditioning? As architects consider how to reduce the energy demands of new builds, some are turning to the past for simple, low-tech solutions.

At the height of summer, in the sweltering industrial suburbs of Jaipur, Rajasthan in north-west India, the Pearl Academy of Fashion remains 20 degrees cooler inside than out -- by drawing on Rajasthan's ancient architecture.

While the exterior appears very much in keeping with the trends of contemporary design, at the base of the building is a vast pool of water -- a cooling concept taken directly from the stepwell structures developed locally over 1,500 years ago to provide refuge from the desert heat.

Award-winning architect Manit Rastogi, who designed the academy, explains that baoli -- the Hindi word for stepwell -- are bodies of water encased by a descending set of steps.

The entire building is raised above the ground and a pool of water -- 

integrated into a recreation and The entire building is raised above the 

ground and a pool of water -- integrated into a recreation and exhibition 

space -- keeps temperatures low through evaporative cooling. As 

architect Manit Rastogi says, "When water evaporates in heat, 

it immediately brings down the temperature of the space around it."

"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.

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The building is protected from the environment by a double skin which is 

derived from a traditional building element called the "jaali" which is prevalent 

in Rajasthani architecture. The double skin acts as a thermal buffer 

between the building and its surroundings.

Rastogi wonders: "How did they think up something so elaborate and yet so simple in its basic philosophy?

"How do you begin to think that you can dig into the ground and use the earth as a heat sink, have access to water, put a pavilion into it so that its comfortable through the year? It takes a lot of technology for us to think up something that simple now."

But 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.

Pearl Academy's outer skin sits four feet away from the building 

and reduces the direct heat gain through fenestrations, while allowing 

for diffused daylight. In this way, it filters air, light, and privacy.

How did they think up something so elaborate and yet so simple in its basic philosophy? 
Manit Rastogi, Architect

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.

As a happy by-product, it also casts striking shadows across the academy's corridors

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.

This method was employed over 1,500 years ago by local Rajasthanis, 

who built "baoli" or stepwells -- bodies of water  surrounded by a descending

set of steps, helping to create a microclimate in the surrounding structure.

The success of the academy's eco-design has had an impact. Regulations -- based on these passive cooling techniques -- were introduced last year for all new Indian government buildings.

The Pearl Academy also draws on courtyards and shaded spaces with 

concrete pillars that feature in ancient buildings, as seen here at 

the Adalaj stepwell in the Indian state of Gujarat.