Re: Liveable temp/ geothermal
From: John Beutler (
Date: Sun, 27 Jan 2008 19:24:46 -0800 (PST)
People who have visited us have asked me about retrofitting ground source heat pumps in existing construction. I've thought about it a bit and one conclusion is that its success, at least in Maryland-like climates, depends on having a high-performance house shell - excellent insulation, top-rated windows, etc. I think that trying to put it into an older house could be very disappointing if the other factors were not tightened up substantially. Doing this may be very I think its best application is in good quality new construction.

Now for a large building (like Eastern Village) things may work out somewhat better with retrofitting, than for single family or duplexes, which is what we have here in Liberty Village. This is because the exposed surface in a large building is so much less per unit, so there is less to insulate.

Also, I would second the observation that you don't yo-yo the temperature settings with ground source - one family who moved in here didn't realize this and ran up a big electric bill the first month - rapid changes of temp settings turns on the auxiliary heat coils, which are expensive to run. We always ramp the settings a couple degrees at a time and basically leave it at one setting all winter and then a higher setting all summer.



At 10:00 PM 1/27/2008 -0500, Sharon Villines wrote:

On Jan 27, 2008, at 9:31 PM, David Heimann wrote:

>       Can one install geothermal systems retroactively in a development
> after it's built, or is it only feasible to install at the beginning?

I think it depends on whether you have ground space and basements. You
need to dig the wells and they have to be a certain number of feet
apart. Then you need to run the pipes from the wells horizontally
underground and up into the homes to the HVAC units.

So it really depends on your building design and whether this is

If you have basements and forced air heating already, I assume it
would be just a matter of replacing the HVAC units with geothermal
units and running the pipes (or water loops) into the basement.

Sharon Villines
Takoma Village Cohousing,Washington DC

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John Beutler
Liberty Village, MD
jabeutler [at]

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