Living Paradigms is a series about what we can learn from the customs and cultural practices of others when it comes to solving problems. It is sponsored by Wonderstruck.
During the scorching summers in Bharuch, a city on India’s west coast, Anjali Choudhary’s drawing room on the ground floor became unbearably hot. With no air conditioning and temperatures surging to 110 degrees Fahrenheit, it was difficult even to sit in the room, she says. Then, last summer, Choudhary came across a special type of curtain, made of dried roots of vetiver grass, commonly known as khus.
Vetiver (Chrysopogon zizanioides) is a tall bunchgrass that grows abundantly in India. Its exceptionally dense root system can extend up to six feet deep in six months, making it an excellent solution to soil erosion. Out of the soil, the dried gnarled roots provide a whole new service: cooling.
Two khus curtains hang outside Choudhary’s ground-floor drawing room. Courtesy of Anjali Choudhary
Woven khus curtains or screens are typically hung in doorways or windows and sprayed with water. As hot air passes through the damp screen, it undergoes evaporative cooling, significantly reducing indoor temperatures. The khus curtains Choudhary bought online came with a purple cloth border. She hung two of them on the concrete awning of her drawing room window, at a slight angle, and sprayed them with water throughout the day.
Generations of South Asians made curtains and mats out of these unassuming roots, incorporated them in refreshing beverages and extracted essential oils from them to beat the heat. But as rising temperatures and rising incomes made mechanical cooling more common, khus began to disappear from homes. Now, experts say this low-cost, low-tech cooling solution is worth revisiting as India grapples with extreme heat driven by climate change — and exacerbated by air conditioning.
“The great irony of air conditioning is that it heats the planet,” says Sylvia Houghteling, an art historian at Bryn Mawr College specializing in South Asia who has written about the cooling history of khus. While simple fixes like khus can never fully replace ACs, she says, “these modes of cooling that aren’t simultaneously emitting carbon [and] burning energy to produce, I think are really important.”
For Choudhary, the khus curtains have made a real difference. “After putting [up] the khus curtains, the temperature is somewhat regulated, we can now easily comfortably sit,” she says.
This wasn’t Choudhary’s first time using khus. When she was growing up, desert coolers, boxy devices consisting of a fan, a water tank and wet wick or padding, were a common fixture in Indian homes, including hers. The padding to soak the water and cool the air drawn in by the fan was often made of khus.
The curtains aren’t new either. Traditional South Asian blinds, known as chicks, were made out of khus roots and hung in places where you could sprinkle them with water regularly without fear of ruining carpets or furniture, says Vibha Varshney, who heads the biodiversity and food unit at the Centre for Science and Environment in New Delhi. They can help to keep people cool outdoors, too: They work great on balconies and verandas and can also be used in public spaces. Earlier this year, Mahila Housing Trust, a nonprofit that works on heat resilience, teamed up with city officials to retrofit some bus stops in Ahmedabad with khus blinds and a high-pressure mist system to bring relief to commuters.
Anjali Choudhary sprays water on a khus curtain outside her bedroom window. Courtesy of Anjali Choudhary
Beyond evaporative cooling, khus also works in an unexpected way: through scent. “I sometimes place some roots in an urli [traditional bowl], sprinkle water on them and keep them under the fan,” says Varshney. “Just the fragrance makes the room feel cooler.”
Certain smells can feel warm or cool to us. Mint gives off a distinct coolness, while the smell of chili peppers or garlic is often associated with heat. Scientists say this happens because some odors can trigger sensors in our face that detect temperature, pain and touch. Known as trigeminal perception, this phenomenon is sometimes referred to as the “feel” of a smell.
When sprinkled with water, khus effuses a woody, earthy aroma that many find soothing. “When water is thrown on it, winter seems to arrive in the midst of summer,” one 16th-century historian wrote. In a 2021 study on vetiver oil’s complex chemical composition, chemists wrote it has a “quasi‐pheromone‐like effect” on perfumers and consumers alike, noting that it appears in more than a third of all fragrances.
Khus has also been part of traditional South Asian systems of medicine. Dr. Trupti Patil-Bhole, an associate professor in Ayurveda at Bharati Vidyapeeth University, describes a recipe from 100 B.C.E. to treat fever: Six herbs, including khus, are mixed with a large quantity of water and boiled until the solution has been reduced to half its original volume. Drinking this, she says, aids in bringing down the burning sensation of the skin and internal organs.
Research has shown that the chemicals in vetiver roots have antimicrobial, anti-inflammatory and antipyretic (fever-reducing) impact, among many others, says Varshney: “Inflammation and infections tend to increase body temperature, and vetiver could be cooling the body by reducing these.” Studies suggest that vetiver oil inhibits the synthesis of fever-inducing substances called prostaglandins.
Sharbat, a refreshing drink make from khus. Credit: mirzamlk / Shutterstock
The most popular khus preparation these days is a sweet, sticky emerald green concentrate available in bottles, which can be diluted with water to make a refreshing beverage. “However, this is full of sugar and the green color is from the use of a dye,” says Varshney. Instead, she recommends a simple cold infusion in water. Many people merely toss a handful of dried roots into a terracotta pot of drinking water to enhance the soothing effect of the naturally cooled water inside the pot.
When Mughal rulers who came to India in the 16th century missed the cool climes of their Central Asian homeland, khus came to their rescue. In the 18th century, khus screens signaled privilege, and they appear in paintings depicting Rajput rulers, says Houghteling. However, traditional cooling solutions like khus were sidelined during the colonial era, she explains, when British officials instead favored importing ice all the way from New England. “That kind of silences or overwrites a long history of very intentional cooling that used more readily available materials and deep knowledge of more sustainable means of cooling,” she says. Later on, the convenience of ACs — instant cooling at the press of a button — made it a more popular option than khus coolers or screens that needed to be doused with water and could make a mess. “Our houses are no longer designed in a way that we can put the khus blinds,” says Varshney.
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Air conditioners became a status symbol for India’s burgeoning middle class, and now, the country is one of the world’s fastest-growing AC markets. To be fair, air conditioning is a necessity in India’s extreme heat and can save lives. Solutions like khus screens work best as a complement to air conditioning. Think about it, Houghteling suggests, “not as full climate control but as the creation of micro-climates so that you’re not just blasting everything with air conditioning but creating small spaces of coolness.”
Khus screens may also not work for all spaces. Choudhary first hung them over her bedroom window, from curtain rods indoors, but it made the room too humid. The blinds may also not be effective if there’s no ventilation, she says, and drenching them every day can test one’s patience.
But it’s worth the effort, Choudhary says: Not only does it reduce her electricity bill, but as she puts it, “you are contributing to your planet’s health, so why not.”