Blending ancient wisdom and modern precision to cool buildings and reduce energy consumption.
By Philip Gray
The average healthy human body temperature ranges between 36.5°C and 37.5°C. When external temperatures exceed this, the body must work harder to regulate its internal heat. If the body can’t cool itself effectively—especially during prolonged exposure to extreme heat—it risks heat exhaustion, heatstroke, or even death. This is especially dangerous for vulnerable groups such as young children, the elderly, pregnant women, and those with underlying health conditions. In other words, cooling isn’t just a comfort—it’s often a necessity.
But here lies a troubling paradox. The very technology most people rely on to cool down—air conditioning—is itself contributing to the warming of the planet. Globally, air conditioning systems and electric fans already account for about 10% of total electricity consumption. In some of the hottest populated regions, up to 70% of peak residential electricity demand is used just for cooling homes. And as global temperatures rise and heatwaves become more frequent, this demand is only growing—particularly in rapidly urbanising, low-income countries. So we’re trapped in a vicious cycle: the hotter it gets, the more we cool—and the more we cool, the hotter it gets.
The underlying causes of this problem go beyond just rising global temperatures. Modern buildings are often designed with cost and speed in mind, using cheap materials that do not regulate temperature effectively. This hasn’t always been the case—many ancient and Indigenous cultures developed building techniques perfectly suited to their environments. However, in recent decades, we've abandoned much of that wisdom in favour of cost-cutting and profit maximisation – now, we're paying the price.
CoolAnt, an Indian startup, wants to break this cycle by offering low-tech, nature-based cooling solutions that don’t rely on electricity. Their goal is to make indoor spaces safer and more comfortable—without contributing to climate change.
Their cooling walls are made from lots of terracotta cylinders. Terracotta is a kind of clay that soaks up water easily. Water continuously flows through these cylinders, keeping them wet.
When water evaporates (turns from liquid into vapor) from the surface of the terracotta, it pulls heat from the air around it. This is because evaporation requires energy (heat), which it takes from the air, cooling that air down. This process lowers the temperature of the air nearby by about 6 to 8 degrees Celsius—pretty significant for natural cooling. Because this cooling happens through natural evaporation, it doesn’t need any electrical power like fans or air conditioners. They use computer modelling (computational fluid dynamics) to design the shape and layout of the terracotta pots to maximize their cooling capacity.
Beyond just keeping spaces cool, CoolAnt’s work helps revive traditional culture by employing local artisans and keeping ancient Indian pottery techniques alive. Their cooling walls aren’t just practical—they’re also beautiful, serving as striking architectural features that add character and style to the spaces they’re built into.
CoolAnt’s systems aren’t meant to completely replace air conditioning. But in homes, schools, offices, and public areas, they can significantly reduce the need for energy-hungry AC. In fact, many of CoolAnt’s clients have seen a reduction in mechanical cooling use by 30–70%, depending on the environment. That translates to lower energy bills, fewer emissions, and a reduced risk of heat-related illness.
That said, the system does have its limitations. Because it relies on evaporation, it’s less effective in places with high humidity. It also uses a small amount of water, which needs to be managed carefully—especially in regions where water is scarce. And while it’s great for everyday comfort, it’s not suited for environments that need to stay consistently cold, like food storage facilities.
Having said that, CoolAnt reminds us that not all innovation comes from new technology—sometimes, it comes from looking to wisdom of the past.