Reviving Green Traditions: Forgotten Air-Cooling Methods and Phytoremediation

Most parts of India experience high temperatures during summers for ages and our ancestors have been surviving without air conditioners and refrigerators. When foreign invaders and colonizers came to India they too started using our traditional methods to survive the hot summers. It’s true that temperatures have risen sharply and these gadgets do provide relief but at the same time  increase heat in the environment.

Inventors’ are continuously looking out for ways to reduce power usage, heat generation and cool roofing but sometimes going forward is not the answer. Sustainable solutions exist  in the past too.

One such solution of cooling homes, offices and cars  was the norm few decades ago. As with all natural options there are always some other benefits both known and indirect one. This option of natural cooling had a long list of such benefits. Its starts with no power usage, no further heat generation, local resource, local employment generation and a remedy for some of poisons we fill our earth with. You must be wondering where this magic wand has come from. Its a wonderful gift of plant kingdom. One of the best phytoremediation plants where plants are used to clean up soil, water and sediments.

This wonder plant has raised curiosity of Chinese scientific community so much that most of the research for its usage is coming out of China recently. They too are having a tough time with pollution and consider this plant nothing less than a miracle. Unfortunately we were using it for long without understanding the importance.

This plant is shown to clean water and soil by taking up the heavy metals as well as nitrogen and phosphorus balancing. Conserves and retains water in soil. Infact sometime back there was a story of two ragi farmers in Karnataka, one of whom had planted this on the sides of the field and his saplings survived when there was no rainfall for a month. There was also an experiment in southern India’s tea gardens for water and soil conservation using this plant, which was very successful though didn’t make it in big news.

This plant has a wide range of survival conditions, from drought to submerged state and can be used as a water cleaner in hydroponic farm. Many times used for salinity removal after cyclones make coastal lands saline.






This is one of the prime plants for oil refinery waste water treatment and landfill/leachate phytoremediation It survives and grows fast picking up all the toxicity in the soil/water. Gives aromatic oil having uses in many herbal remedies.

A generation ago an experiment with this plant to stop soil erosion due to heavy rains and floods started and became very successful to be followed in many countries after India but it failed to awaken interest in regular farming and co farming of this plant due to financial returns decreasing to zero.

Till thirty years ago there were skilled craftsman who would take the roots of this plant to make beautiful curtains, mats and fans. Yes, you guessed it right. Its Vetiver or Khus.

All the government offices had khus curtains or “Khus ki Tattie” . Water was sprayed on it and even in hottest of summers it would keep the interiors cool by evaporation. A familiar sight was clerks –“babus’ sleeping in their chairs after heavy lunch, inside the cool and fragrant office  room, while the peon kept the curtains wet. In colonial era ‘Sahibs’ had regular watering persons called ‘Bhistis’ who would come and drench these curtains which were hung on all the sunny windows and verandahs.

Image result for khus curtains


In many places Indian mother is portrayed clad in saree and slowly moving the hand fan over her sleeping kid/husband. The fans made out of khus were quite useful during summer power outages. As a kid I have experienced the cool and fragrant air coming on me while my parents slowly swung them over me.

Right up to the mid-80s, manufacturers in India did not provide cars with air conditioners. So what did the guys who purchased Fiats or Ambassadors do?

At the onset of summer the markets were flooded with khus tatties, mats and hand-fans. Motorists would buy these khus-tatties and tie them on the roofs of their cars. Before setting out on any journey, they would pour water over these grass mats, and as a result the roof of the car would cool down and drop temperatures inside the passenger compartment by about 10C or more. The evaporation of the water from the mat would further cool the metal surface of the roof due to ‘evaporative cooling.

All the red beacon Ambassadors had a khus mat tied on the roofs all year because collectors and ministers needed to cool down while visiting their constituencies.

These khus tatties were woven so nicely by special techniques that it retained most of the water sprayed on them and didn’t need much water in regular use. Water dripping down was often collected via drains made in the windows or flower pots were placed under them. (Photo is from a useful blog article on khus)


These mats could be used for long and when it need to be replaced the old one was used to cool roofs, make hut -roofs or for cow sheds. Traditional weaving method is now lost and its mostly just placing dry grass root on a surface and tying them . Due to this shortcut the curtains cannot be used for more than a season. The maintenance issues and arrival of electrical appliances almost killed this art.

Imagine how much power would have been saved if we continued using it in one way or other. Apartments could put it up on the wall which got direct sunlight to prevent it heating up and heating the rooms inside. In place of chemical cool-roofing solutions one could just spread the mats on the roof/ terrace soaked with recycled water.

Cars parked under the sun become  like an oven and need the air conditioner on full blast to be able to sit inside. A moist khus mat could keep the car cool when the sun is brightest and would not require AC on full. Educational institutions and commercial establishments could cut down the cost of power consumption if they used these mats at strategic places.

Most of the eco tourism in India is a paradox where this tradition can help. One pays a huge amount of money to spend time in the nature inside one of the reserve forests but need air-conditioned rooms which heat up these parks further. How good it would be for the flora and fauna if these resorts use Khus roof cooling in place of AC’s

Our traditional green ways of life are  taken up by the developed countries in a new avatar. This is one of our tradition world is not familiar with it yet. Hopefully before that we would take it up again.


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A physicist turned green living advocate.

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