One of the most promising energy saving technologies around is geothermal. The process simply exploits the difference between the temperature of the air and the relatively constant temperatures found underground. You pipe the coolant for hundreds of yards underground and return it to your building much warmer or cooler than it left. The biggest obstacle in the past was putting in the pipe, but today thanks to horizontal directional drilling, you can install geothermal systems for much lower costs, in smaller spaces with no surface digging. Expect a lot more of this work to be let if the stimulus package keeps all the alternative energy tax breaks intact.