Which is hotter: The sari or bikini?

Research in America commissioned by a society of air-conditioning engineers says it's important to study thermal properties of the sari and burqa if AC makers want to create technology specifically suited to cool rooms across Asia and the Middle East. Here's how the humble six-yard may influence the design of the next AC you buy (and impact global warming), finds Lhendup G Bhutia

Who would have thought a room full of women dressed only in lingerie could have value apart from being a male fantasy? Turns out, they do, and it's called 'clo value' or clothing value.

Strangely it's not fashion designers but air-conditioner designers, at least in the West, who take this value into account before they plan their tech-design.

Photograph courtesy Saris of India Tradition and Beyond by
Rita Kapur Chishti, published by Roli Books

One clo is the amount of clothing required by a sedentary person to feel comfortable at temperature 21 C, relative humidity less than 50 per cent, and wind velocity not more than 250 centimeters per second.

So each of the lingerie-clad women in that room carries a clo value of 0.05. A woman dressed in full Western winter clothing will carry a clo value of 1.34. The winter clothing will include: a panty, double-knit, long-sleeve turtleneck, a tweed, double-breasted suit jacket, a pair of tweed, straight, long loose trousers with a belt, and a pair of thick socks with hard-soled street shoes; all of which will weigh 2.57 kgs and cover 88 per cent of the body. (Sourced from Elizabeth A McCullough and Byron W Jones's study A Comprehensive Data Base For Estimating Clothing Insulation in 1984.)

Although research in the clothing value field is relatively old, with documentation on garments' insulation properties, it is now on the tenterhooks of a revolution that will impact cooling and air conditioning systems across the globe.

Because sometime later this year, boffins will transform into store attendants, draping a sari around a manikin, a life-sized human model used in education. They will adjust every fold before trying out another outfit. Their subject of study ufffd non-Western attire.

California-based John Stoops, who will oversee the research project for the American Society of Heating Refrigerating, and Air-Conditioning Engineers (ASHARE), explains, "Clothes in non-Western regions are different from the West. The sari could be made of silk and differs from our ensembles in terms of vapour resistance and style. Yet, there is no data on its insulation properties."

The study also has immediate, although seemingly unrelated utility value. "This information can influence the design of ventilation and AC systems in non-Western regions," he says.

Invitations for research proposals are being entertained. Once selected, the team will commence work from September and will work with a time frame of 15 months. Around $1,40,000u00a0 (approx Rs 6,164,905) has been allocated to research.

How it's going to work
Researchers will use an electrically-heated copper manikin and test it while draping it with a variety of non-Western clothes. The study will factor in the structure of the garment in various seasons, the fabric, its thickness and density, postures, and air movement relevant to situations in the building. Researchers will take into account clothing from the Middle East, China, and South Asia (India and Pakistan), if not other regions.
There is much to be studied, says Stoops. "Many would think those who wear burqas in the Middle East feel extremely hot, but the looser fit may in fact be promoting movement of air, thereby making it a cooler garment."

In fact, non-Western cultures are already experimenting with fabrics so that they are cooler and eco-friendly. For instance, the 'eco-hijab', a contemporary term used to describe the relationship between ecologically driven Muslims and their dress sense, has resulted in organic hijabs from bamboo.

Bengaluru-based founder of Do U Speak Green, India's first fully-organic online clothing store, Shishir Goenka agrees. "Organic clothes are cooler and better for the skin. Bamboo has a natural property that controls sweat."

What! say Indian AC makers
Ironically, manufacturers and installers of AC systems in India, home to the sari, do not take into account the insulation properties of apparel.

Pravin Patel, proprietor of Hi Tech Cooling Systems, a Gujarat-based firm, is surprised at the proposal.

Prasanna Pahade, General Manager, Corporate Planning at Voltas Limited, an Indian engineering solutions provider, says factors like room temperature, number of objects in the room, glass windows, and position of the room are taken into account while manufacturing and installing ACs. Clothing value doesn't feature in his list although he agrees that it could be an important decider. "A mall in Saudi Arabia milling with 1,000 burqa-clad ladies cannot have the same AC system as one in Australia, where people are dressed in shorts. Energy can be saved," he says, but with certainty that no Indian AC company currently pays attention to insulation properties of clothes.

Our cross to bear
Air conditioning is an energy guzzler ufffd when an AC absorbs heat from the ambient air and releases it into the environment outside, it needs a lot of energy to directly impede the Second Law of Thermodynamics, or the Entropy Law. The law states that heat naturally flows from a hot to a cold area.

Katy Rustom from the Centre for Environmental Research and Education, a non-profit organisation that works with corporate offices to help with green practices, says, "Everyone talks about switching to LED lights, but air conditioners are far bigger guzzlers of energy."

According to Stoops, knowledge of the insulation properties of clothing in India and China are doubly important because of their emerging markets. "A lot of business gets conducted in these countries, which mean lots of air conditioned buildings. You cannot operate ventilations and air conditioning without factoring in clothing," he says. "Otherwise, precious energy is wasted."