The most efficient way of distributing geothermal heat is through radiant in floor tubing, or forced air duct system. A duct system is ideal because it can deliver both heat and air-conditioning. Unfortunately, standard hot water baseboard (HWBB) usually needs to be supplemented (with additional baseboard, fan coil units, or radiators) to provide proper heat output. HWBB, radiant and duct systems can be incorporated in most retrofit applications.