I've heard that measured performance of actual, installed geoexchange systems can be much lower than advertized COP numbers.

Is anyone aware of any accessible, reliable reports about real-world performance of these systems?

If not an academic-level paper, anyone have any good anecdotal information?

Thanks in advance,


Tags: geothermal

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I agree with NG's current prices, but do you REALLY think NG is going to stay cheap once it's able to be exported, or regulation and Taxes are applied as they are with oil? The US has the infrastructure to import LNG, but not to export it. Once the infrastructure is up and running, LNG will be priced on global market. Right now it is about half the cost of that.

Once NG goes to global pricing electric power rates will increase also. Keep in mind what most of the new power plants use for fuel...

Though none of my relatives or friend have installed this system but when I Googled the topic I found that GeoExchange is the most energy-efficient, environmentally clean, and cost-effective space conditioning system available as per the Environmental Protection Agency. It average about 40% more efficiency than air source heat pumps and 48% greater efficiency than gas furnaces.

Geo systems may be more efficient than NG, but they don't cost less to run since NG is such a low cost fuel source.

Could be...could be not.

In expensive electric markets such as the northeast, NG is likely a slam dunk for those who have it.

OTOH in cheap electricity markets, $0.08 or less, even if NG is available, Geo has a place at the table if for no other reason that, done right, it saves greatly on cooling in temperate zones.

Interestingly, geo is a bit of niche product in Florida - Our ground water temps are too warm to get the 30-40 EERs touted in ads, and our heating needs are too small to justify major expense. Where geo kicks butt is at the beach, where sand and salt demolishes an outdoor compressor unit in 5 years.

I'll share what I've found struggling to get a geo system to justify a geo system at my place:

1.  You need the right distribution system in place already, low temp hydronic or high volume low pressure well insulated ducted air system

2.  You need a DEEP well so you don't need to drill a new one OR a big open field where no one will raise issue with the gi-normous hole, esp. inspectors (siltation fencing, retainage / settling basins, safety fencing...)

3.  You need an installer who isn't just good, but honest enough to pass on your job if it's not a slam dunk to work.  If you want to pursue this, ck references alot on installers, back 5 yrs and more, and only use them if everyone is thrilled an saving money, say 10 or more.  This is a big investment, it has to work.  I was lucky enough to find an installer whos' family has been doing geo's for 3 generations - Archibald in Kingston NY, and another who's been doing it forever, Altren, both shared their knowledge willingly.

If you want an alternative, insulate the crap out of your attic, basement / foundation up to and over rim joist - preferably on the outside of the building, you might try a frost proof shallow foundation especially if you have a finished basement and don't want to rip off all the wall materials.  Air seal.  Put in a HRV ventilation system.  Get a high efficency boiler, fuel that's cheapest in your area.  If your siding needs replacing, add 4 inches of high density rock wool under it.  You'll save 30% or more in yrly energy costs.

Best practice put your investment into sealing and insulation. One time cost that can bring your heating/cooling down by 90% with proper orientation. Mini split for heat/cool and ERV/HRV for IAQ. Simple cost effective without having to go into rocket science.

Just wanted to check in and thank all the great responders.

I particularly appreciate those who took the time to post links to studies.

Overall it would seem there are not many studies, and they don't include many houses--but the studies that have been done show COPs in the 3 range, certainly not 5 or 6.


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