Maintaining air circulation during a power failure is not a difficult thing. The oldest methods include ventilation,
in which a double glass is fitted on the wall near the ceiling. But TERI, Tata
Energy Research Institute uses a really novel method of air circulation.
In TERI, there is an extra black wall with windows on the side that faces the sun. As black, a great absorber, taps sun’s energy it gets
heated up fast. Due to this heating, the air between the two walls rises and it creates a low pressure. In turn, the air from inside rushes out to the space between the walls and air from the window on the opposite wall enters the room thus maintaining circulation naturally. This continues until the outer black wall is heated by the sun. This does not cost much in comparison with the power that is used up by fans etc that would be used during the day. Cumulatively, we would save a lot of energy and in today’s world energy saved is energy gained. This is an excellent way of tapping solar energy