Do geothermal heat systems live up to the hype?
Robert Swinburne
| Posted in Mechanicals on
As an architect, I have been hearing a lot of both good and bad about geothermal systems. Some of the worst comes from builders and engineers at conferences who are not trying to sell geothermal but have experience with them. Not being an expert, I council clients to put money in to a super-insulated shell first although clients always would rather spend money on a more expensive and complicated heat system than triple glazed windows. Any input would be appreciated.
-Bob Swinburne
http://www.swinburnearchitect.com
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Replies
Robert,
In case you missed them, you should read these blogs:
https://www.greenbuildingadvisor.com/blogs/dept/green-building-blog/ground-source-heat-pumps-don-t-save-energy
https://www.greenbuildingadvisor.com/blogs/dept/green-building-blog/ground-source-heat-pumps-have-low-opperating-costs
It's my opinion that the money spent on a GSHP would be better spent on envelope improvements.
Robert,
I agree with Martin 100%. The consumer is often looking for buzzword features for their home rather than the benefits derived from those features. Few builders and fewer consumers truly understand home performance. Try asking your clients what they are hoping to achieve by requesting a certain feature - in this case a GSHP. If you can identify a problem they are trying to solve and/or avoid, you can direct them to the appropriate and most cost-effective solution.
Geothermal systems make economic sense only if you have:
1. Low electricity costs
2. High oil & gas fuel costs
3. Low temp radiant heat surfaces
4. A well-insulated home
If you don't have all of the above working for you, chances are a geothermal system won't be an economic proposition, nor even a greener alternative to the fossil fuels because geothermal systems need a fair amount of electricity to run, generation of electricity is an inefficient process, and usually it's generated with fossil fuels.
Moreover, geothermal systems typically cost tens of thousands of dollars to install, and operate much less efficiently if you need to boost the temp up to achieve sufficient heat from traditional ducts or baseboard convector/radiators. By the way, electricity costs vary quite a bit here in the USA. In the northeast we pay $.23/kWh, while some western states prices are as low as $.07/kWh.