The sun has set. Windows close, curtains are drawn and air conditioners hum across the city. As summers grow harsher, cooling has become less of a luxury than a necessity for many households. Yet architects and environmentalists say India’s growing dependence on air conditioning is also reviving interest in older building techniques designed to reduce heat before machines became common.
Architect Murali Murugan tells TNIE that several traditional design elements still offer lessons for reducing indoor temperatures and improving ventilation, particularly in regions with hot climates.
One of the most common features in older South Indian homes, he says, was the courtyard, an open central space that improved air circulation inside the house. “Even a small 500 sq ft house in earlier times would have a tiny courtyard. That itself generated an air draft and improved comfort indoors,” he says.
Building materials also played a role. Murali compares modern concrete roofs to a heated dosa pan that continues radiating heat long after sunset. Older homes often used tiled roofs, hay roofs or reed-based roofing systems that contained tiny air gaps, slowing heat transfer indoors.
Traditional mud walls, sometimes more than a foot thick, also reduced heat transfer more effectively than many thin concrete walls used today. Their porous nature allowed them to cool faster after absorbing heat.
Windows and shading systems were designed differently too. Wooden shutters reduced direct sunlight, while verandas, corridors and arches helped shield walls from heat gain. Older Indo-Saracenic and Mughal-era buildings often used high ceilings and ventilators to release rising hot air naturally.
Murali says some of these ideas are now reappearing in modern architecture through passive cooling techniques, reflective roofing, cavity walls and biophilic design. He points to architect Laurie Baker’s rat-trap bond wall system, which creates air cavities within walls to improve insulation and reduce heat transfer.
“In Rajasthan, clay pots were sometimes placed upside down on rooftops to create insulating air pockets. Madras Terrace roofs also used layered brick and lime systems that reduced indoor heat,” Murali says.
At the same time, architects caution against romanticising older homes entirely. Traditional structures evolved under very different conditions, including lower urban density, larger land parcels and fewer multi-storey buildings. Many older homes also required regular maintenance and were not always affordable or accessible to poorer communities.
Modern apartment culture emerged partly because rapidly growing cities could no longer expand through large, low-rise housing patterns. Features such as courtyards, thick walls and large verandas are often difficult to incorporate into compact urban plots and high-rise apartments where developers prioritise floor space.
Still, researchers and urban planners say several climate-responsive ideas can be adapted to contemporary housing. Cross ventilation, shaded balconies, reflective roof coatings, insulated walls, better orientation to sunlight and increased tree cover are increasingly being studied as ways to reduce indoor heat and electricity consumption.
Murali says that even simple interventions can make a difference. “Reflective white roof coatings alone can reduce indoor temperatures by nearly three degrees Celsius in some cases,” he points out.
Environmentalist Donthi Narasimha Reddy argues that dependence on air conditioning alone may become increasingly difficult to sustain as temperatures and electricity demand continue rising.
Every summer, electricity consumption rises sharply as millions switch on cooling systems. Households often consume several times more electricity during peak summer months than during milder seasons. This has implications not only for power generation but also for emissions and urban heat.
“Many people think heat can simply be solved through air conditioning, but buildings themselves must be designed better,” Donthi tells TNIE.
He also points to concerns about thermal inequality. Air conditioners release waste heat outdoors, which can worsen temperatures in already dense neighbourhoods. While middle-class and affluent households can often insulate themselves from heat, poorer communities living in crowded settlements remain more exposed.
“It becomes a form of externalisation, where the environmental burden is shifted onto others,” he says.
However, experts note that air conditioning itself cannot be dismissed outright. During severe heatwaves, cooling systems are increasingly important for the elderly, children and people with health conditions. Public health researchers have warned that access to cooling may become critical as extreme heat events intensify across Indian cities.
For planners and architects, the debate is therefore less about rejecting technology and more about reducing excessive dependence on it. Passive cooling alone may not eliminate the need for ACs in extreme summers, but it can reduce energy consumption and improve comfort when combined with modern engineering and materials.
Recent research on climate-responsive architecture has increasingly focused on combining traditional design principles with newer technologies rather than treating them as opposites. As Indian cities continue warming, experts say future housing may need to balance density, affordability and thermal comfort more carefully than before.