Monish Siripurapu: The architect using terracotta to cut down AC bills by 30%

In medieval India, when air conditioners did not exist, forts and royal buildings were kept cool through evaporation. One way to do it was by constructing step wells, which acted as heat sinks. The other method, seen in the Red Fort at Delhi and Agra, involved mixing water droplets with air using fountains and cascades to improve the thermal comfort of the structure. 

Evaporative cooling works on the simple principle that air flowing across the water will become cooler by gaining water vapour and help bring down the temperature.

Over 550 years later, Delhi-based architect Monish Siripurapu is using this sustainable evaporative cooling technique to keep modern buildings cool and cut energy costs by 15 to 30 percent.

Monish’s startup CoolAnt envelops buildings with trendy terracotta shields, which act as a second skin of the building. They protect the structure from heat and enhance cooling by lowering the temperature. 

Combining traditional with the modern

“By combining modern design sensibility with traditional methods, we have developed cooling facades that reduce temperatures by around 5 to 6 degrees Celsius,” says Monish, founder of CoolAnt, a start-up focused on natural cooling solutions. 

Monish is a graduate of the School of Planning and Architecture (SPA), Delhi. He is the founder and principal of Delhi-based Ant Studio which provides a bridge between Art, Nature and Technology, thus the name ANT Studio. CoolAnt is one of the means of achieving the goals of ANT Studio.

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Inspired by ants that are known for constructing climatically-sensitive and sophisticated ant hills, CoolAnt provides simple and artistic solutions made from natural materials.

The start-up uses shading, ventilation, and evapotranspiration, a process by which water moves from the land surface to the atmosphere via evaporation and transpiration. These methods involve the use of different terracotta designs for creating cooling facades. 

CoolAnt offers four design solutions -- Beehive, Binary, Coral, and Aerofoils, which are implemented according to the design and height of the building. 

“Beehive structures consist of numerous concentric terracotta circles, while binary designs use flat terracotta tiles. Coral structures are cylindrical in shape, and the latest concept, Aerofoils, features customized terracotta tiles shaped like leaves, with a broad circular end tapering towards the tip,” Monish explains.

Why terracotta

Terracotta pots have been in use across India for cooling water for thousands of years. Even today, matka and surahi are used to keep water cool in the summer. When water seeps through the porous layers of terracotta, it evaporates at the outer surface, leaving the inner surface cool. 

“We use the same principle but in reverse order. Terracotta tiles form an insulation barrier between the building walls and heat waves. As the dry hot air passes through them, the water circulating through the terracotta tiles absorbs heat, adds moisture and lowers the temperature. So the air exiting the other end is cooler,” he explains.

Evaporation of water helps to passively cool buildings, reducing the energy needed for air conditioning.

Moreover, terracotta is eco-friendly, unlike plastic, making it an easy choice of material, he adds.

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The designs for the facades are selected based on the structure. “For low-rise buildings, any design like Beehive, Binary or Aerofoil would work. However, complications arise in the case of high-rise buildings. We don’t recommend Binary or Beehive as it would require a lot of maintenance,” says Monish.

“CoolAnt has the Aerofoils solution for multi-storeyed buildings. They are very robust, and the direction and installation are quite easy,” he adds.

It has set up around 30 binary and beehive installations in Lucknow, Hyderabad, Kurukshetra and Raipur besides Delhi-NCR. CoolAnt has eight aerofoil projects in the pipeline.

“We are trying to keep things very local and sustainable but the quality of terracotta varies from one region to another. There are a lot of factors which define the quality of terracotta, for example, the ratio of sand and clay and the temperature at which it is heated. We are very careful about the quality of terracotta used for our designs,” says Monish.

CoolAnt’s facades can help reduce the load on air conditioning by up to 32 to 40 percent depending on the climatic condition and structure of the building.

According to The Energy and Resources Institute (TERI), running an AC at 27 degrees instead of 18 degrees Celsius can cut energy costs by 30.8 percent. 

Replacing the AC, bit by bit

“In the current scenario, it is not possible to fully replace air conditioners with these passive solutions. So we’re focusing on reducing their usage, which brings down the electricity bill,” says Monish.

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The effectiveness of these installations varies based on the humidity levels and local temperatures in specific regions. On average, they are capable of reducing the temperature by 5 to 6 degrees Celsius. Their performance can be further improved by optimizing the setup through proper ventilation, shading, and other factors.

In terms of cost, both the binary and beehive installations are similar, with the raw materials being locally sourced. On the other hand, the aerofoils are customized and require specialized manufacturing in factories, which increases their cost. 

The pricing for CoolAnt’s installations ranges from Rs450 to Rs1500 per square foot. 

“We are not focusing on the numbers and finance currently. We are constantly evolving our practices to make it a more meaningful and useful product and expand our reach,” he says.

The use of air conditioners contributes to global warming through carbon emissions, particularly in India's building sector, which consumes about 40 percent of the generated electricity. This consumption, which adversely impacts the environment, is projected to increase to 76 percent by 2040. With the rising demand for air conditioners, the company predicts that around one billion units will be needed by 2050, resulting in the release of approximately 100 million tonnes of carbon dioxide annually.

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While talking about the challenges faced by the enterprise, Monish says, “Our struggles are quite similar to any other manufacturing startup like finding the right channel partners, execution, operation and supply chain issues. But I don’t consider them as challenges as these are learning experiences and all of it will eventually fall in place.”

CoolAnt’s initiative is supported by the United Nations Environment Programme, the Institute of Global Environmental Strategies, and Japan’s Ministry of Environment, among others. 

“We have a few other exciting products in the pipeline but our current focus is to enhance this product in a way that it has a certain appeal and can bring about a meaningful change. Although we are working on specific cooling needs right now, a few years down the line, we would love to work towards cleaning water bodies and reducing the landfills that are contaminating earth and water,” says Monish.

(Riya Singh is a Ranchi-based journalist who writes on women empowerment, environment & sustainability)

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