Cohousing-L Mailing List: Re: Liveable temp/ geothermal

[John Beutler (jabeutler]

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 costly....so 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.

Cheers

JAB


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
> feasible.
>
> 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
> ----
> Sharon Villines
> Takoma Village Cohousing,Washington DC
> http://www.takomavillage.org
>
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John Beutler
Liberty Village, MD
jabeutler [at] comcast.net
http://www.libertyvillage.com/