Save Money with Geothermal You already purchased your property - why not use the free energy source just beneath the surface of your yard? A WaterFurnace geothermal system can distribute an astounding five units of energy for every one unit of electrical energy used. But what does that mean for you? It means you can condition your Knoxville home for far less than your neighbors and friends. The equipment we place in your home is the most economical geothermal products on the market today. Homeowners can realize savings up to 70% for heating, cooling, and hot water!