Natural Air Conditioner/Heater
Since the ground temperature remains between 50-55 degrees F year round we could use nature to cool and heat our houses and businesses. Transfering the heat from the attic through the foundation walls in the basement into the ground in the summer time. Probably could use the fact that heat rises to create a ventilation system that is naturally powered too instead of using an electric fan. Then in the winter, using the difference in temperature between the frost layer and the 50 degree layer to transfer heat into the building using an intricate ventilation system.
Reward: A cleaner and happier Earth