Cool summer tip by an retired Indian scientist who managed to cool his home passively by a huge 5 degree centigrade during summer. And it cost him just Rs. 1000. But you will in fact save more money every month as a cooler home will reduce your AC bills! Here’s what he did in his own words:
tried by (Dr.V Balasubramanian) a retired scientist with specialization in crop and natural resource management, specifically in rice-based farming systems. So, he is naturally interested in conservation and efficient use of all natural resources – land, water, air, biodiversity, and forests. His friend Dr. S.P. Periaswamy is a nature lover interested in finding simple solutions for our common problems.
The main problem in hot homes was the absorption of heat by dark colored roofs which then radiate it inside the home making it sometimes hotter than outside if there’s no AC or less ventilation. Many options like the sun-reflective white paints were very expensive. After a long search on the Internet and several enquiries with paint companies, we found a cost-effective option for painting our roof white – the finely ground (microfine) lime powder. It is sold by commercial names like Janata Cool or Summer Cool. I bought the Janata Cool sold in 5-kg bags with a small packet of translucent crystal inside. The instruction says it has to be dissolved in 9 liters of water, further adding the lime powder and mixing it well, and leaving to dissolve for 10 minutes.
We took 8 liters of water, dissolved the packet of crystals in it, added 500 ml of Fevicol (adhesive) and then mixed in it the 5 kg of lime powder well. We let it for 10 minutes, then mixed the solution well and painted the roof with a wide brush. It covered about 600 square feet (60 square meters) of roof surface. We have to paint the roof either early in the morning (06:00 to 10:00 am) or in the evening (04:00 to 08:00 pm) to avoid inhaling the pungent fumes that emanate from the solution when exposed to direct sunlight and high temperature. You can water the painted surface 12 h later for curing. A second coating is applied 24 hours after the first application. We can water the painted roof for 3-4 times in two days for proper curing. After drying, we can see the bright white roof.
We measured the temperature inside the house before and after painting the roof white with the lime powder: 35 oC before and 30 oC after painting the roof white, a reduction of 5 oC in room temperature, under Coimbatore conditions (16-17 April). We can now comfortably sleep in the bedroom with a fan only in the night. We have avoided the use of AC even during the peak of this summer, with a simple solution like painting the roof white with lime.
The cost in Indian Rupees (Rs) of lime painting for 600 square feet (60 square meters) of roof surface is as follows:
Ingredients: Price (in INR)
Janata Cool lime powder (two bags 5 kg each): 360 (180X2)
Fevicol Adhesive(one litre): 80
Labour Charges: 500
TOTAL 940 per 60 Square Meter / 645 Sq.ft
You can also use this simple solution to beat the heat this summer at an affordable cost