Space Heating And Cooling Accounts Major Energy Demand. Cost Of Energy Is Becoming Costlier Day By Day. One Can Think About Natural Resources, Which Are Still Untraveled. At A 3 Meter Land Depth, Diurnal Fluctuations Can Not Penetrate And Gives Stable Thermal Environment Round The Year. One Can Use It As Heat Source And Heat Sink Purpose. An Earth Tube Heat Exchanger System With An Appropriate Structure, Either In Close Or Open Loop Mode Can Be Develop For A Typical Heating And Cooling Requirement. The System Consumes Less Electric Energy And Hence, Minimizes The Air Pollution And Global Warming. This Book; Therefore, Provides Detail Design To Construct An Environment Friendly System At A Cost-effective Manner.