My grandfather, William L. Holladay, was a refrigeration and cooling engineer. Decades ago, he wrote a pioneering, speculative article on ground-source heat pumps, “The Heat Pump: What it does, and what it may do someday.” The article appeared in the October 1948 issue of Engineering and Science Monthly. (For a basic explanation of how a heat pump works, and the difference between an air-source heat pump and a ground-source heat pump, see Heat Pumps.)
Even back in 1948, my grandfather realized that the Achilles’ heel of ground-source heat pumps was their high cost. He wrote, “To use earth heat, a hole must be dug, and the cost, while not always predictable, will surely be high: maybe from 25 to 50 per cent of the entire project.”
In the six decades since my grandfather’s article was published, engineers have not given up on ground-source heat pumps (GSHPs). Among those who remain enthusiastic about these systems are a group of true believers who are convinced that (a) this is a wonderful technology, and (b) there must be a way to bring costs down.
Ground-source heat pumps are still expensive. One fan of the technology, Brian Clark Howard, has provided the following guideline to system costs: “In our book Geothermal HVAC, my co-author, Jay Egg, crunches the numbers for a typical homeowner, based on his 20+ years in the business. For a home geothermal system, he estimates the total installed cost at $42,000.”
This estimate is similar to those made by two installers of ground-source heat pumps from Maine, Jeff Gagnon and Jim Godbout. In an episode of the Green Architects’ Lounge series on the GBA website, Gagnon estimated the cost of a residential GSHP system (including the cost of a drilled well) at $30,000 to $42,000, while Godbout gave an estimate of $40,000 to $50,000.
Back in 1995, Steve Kavanaugh, a…