Earth Tube Heat Exchanger
ETHE is a device that enables transfer of heat from ambient air to deeper layers of soil and vice versa.
It uses the known fact that temperature regime in deeper layers of soil say beyond 3m depth remains stable permitting large mass of soil to be used as sink and source of heat. In Ahmedabad area for instance the deep ground temperature remains close to 27 0 C . ETHE based cooling does not require water and is therefore specially suited for greenhouse in Kutch region as also for cattle houses. Several working installations of ETHE cooling systems have been commissioned .