My roommate Bob and I recently looked into geothermal heat pumps and were shocked by the cost of purchase and installation. The largest expense is the excavation for the underground loop system. A series of pipes are buried in the backyard to take advantage of the relatively stable year round temperature found underground. This loop system can be expected to last upwards of close to fifty years, give or take. The actual heat pump is installed inside the home, protected from the elements, plus should last a minimum of twenty years. This is a much longer lifespan than conventional HVAC equipment. The heat pump draws from the free underground energy source, plus easily produces more units of energy than it requires to operate. Bob and I can maintain perfect year round temperature for right around a dollar a day or so. The much lower cost for temperature control should reclaim the higher initial investment within more than two years. I like that the heat pump is seriously quiet, clean and safe. It provides both heating and cooling and maintains undoubtedly even temperature. Plus the geothermal system effectively handles Summer humidity and doesn’t overly dry out the indoor air in heating mode. This was a great choice we made, and we suggested it to all our family and friends!