How India's lattice buildings cool without air con
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"The threat of high heat stress is already present in India, which is expected to worsen in the coming years. This will increase the demand for air conditioners, which have a huge heat output," says J Srinivasan, distinguished scientist at the Indian Institute of Science in Bangalore, India. Alternative ways to cool a building are needed, he adds, including designing building to minimise the requirement for AC to begin with.
Faced with this challenge, some architects are taking inspiration from past solutions, including traditional jaali. "[It] serves as an eco-friendly response to the issues of sustainable cooling and ventilation," says Sachin Rastogi, architect and founding director of ZED Lab in Delhi, who specialises in net-zero buildings.
Passive cooling techniques and building envelopes (which help separate the building interior from the external environment) provide significant thermal comfort by reducing the indoor temperature, cutting the need for air conditioning which can result in energy savings of up to 70%.
Jaali cuts the direct heat entering in a building by breaking down the total square metres of a typical window into a number of small holes. In traditional jaali, the holes are almost exactly the same size as the thickness of the marble or sandstone, says Pandya. "This thickness works to reduce the direct glare of sunlight while allowing diffused illumination," he says.
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