Winter Operation: The underground pipes, called a ground loop, circulate water which absorbs the heat from the earth and returns it to the indoor heat pump. The heat pump extracts the heat from the liquid then distributes it throughout your home as warm air. With the heat removed, the water is re-circulated to collect more heat from the ground. In this case, the loop water is warmer when it comes into the home than when it goes back into the earth since the heat is being removed.
Summer Operation: The indoor heat pump takes the hot air from your home and removes the heat. This leaves behind cool air to be distributed through your vents as air-conditioning. The removed heat from the air is rejected into the earth through the ground loop. In this case, the water is warmer leaving the home then when it returns since heat is rejected into it. This is not a new technology, this is not a science experiment, this is not rocket science. In fact, in many European nations geothermal heating and cooling is the standard. In Sweden and Switzerland, more than 75% of new homes have geothermal. The EPA has acknowledged geothermal systems as the most energy efficient, environmentally clean, & cost-effective space conditioning systems available.