Q: Paul,

Have you found that the economics of geothermal work well? One architect has told me that in recent analyses, the firm is finding that a high-efficiency envelope and other efficiency measures, plus passive solar design, can reduce energy loads to the point that investing in a GT system for HVAC is not cost effective.  They find that a better opportunity for approaching zero net energy, if the owner has the money after making the building passive solar and efficient, is a photo voltaic (PV) system (though I’m not sure how the financial payback compares to GT since PV is so expensive.) I’d sure rather spend my money on PV technology instead of GT with all the moving parts, electric consumption, etc.
—Simon

A:Dear Simon.

Saying that “that a high-efficiency envelope and other efficiency measures, plus passive solar design, can reduce energy loads to the point that investing in a GT system for HVAC is not cost effective” might be somewhat true but then again If your home is extremely energy efficient the cost of installing a geothermal system will be less because you will not have to have such a large system. (As I mentioned before—any reputable renewable energy professional will advise on how to reduce energy needs before designing or installing a system.) 

The cost of a geothermal heat pump itself is only several thousand dollars more than a conventional HVAC. The majority of the extra costs for geothermal as opposed to conventional HVAC are drilling costs (if you go with DX or water loop vertical systems) or excavation costs (if you have a horizontal loop system) and smaller systems need less drilling and excavation. Keeping drilling and excavation costs down can make geothermal systems quite economical in the long run. If building a new house, a good strategy to keep costs down is to excavate for horizontal loops when doing the foundation or negotiate with the company that drills your water well to drill some vertical loops in a package deal that can cut your costs down.

A net zero energy house outside New Paltz has three vertical wells for geothermal and the cost to drill all three wells was about $10,000 total: this cost does not seem exorbitant considering it enables the owners, with the addition of solar PV, to have zero energy costs after the initial capital outlay.

As an incentive, the federal government now has a Residential Renewable Energy Tax Credit of 30 percent of the total cost of a geothermal system, thus making geothermal much more affordable to those who need a tax credit.

My advice to anyone considering geothermal is to shop around and see who will give you the best price on everything, especially the excavation and drilling. With the economy down and new building really slowing down there are contractors out there who need work, so you might be able to get a better price on the excavation and drilling, which account for a major part of the cost.

If any readers have any geothermal stories please email or leave comments at newyorkhousemagazine.com.

Have a question for Paul? We encourage feedback and dialogue about subjects that appear in this column. E-mail Paul at greenadvocate@scheinmedia.com