[GSBN] ground source heat pumps

[David Arkin, AIA]

Hello Catherine, All:

Ground Source Heat Pumps (aka Geo-Exchange) are the most efficient way  
to use electricity for heating and cooling.  They are most cost  
effective in climates (or poorly designed buildings) requiring both  
heating and cooling.

Here's how it was described to me, in the simplest of terms:

Straight electrical resistance heating:  1 part electricity = 1 part  
heat energy
Air Source Heat Pump:  1 part electricity + 1 part energy from air = 2  
parts heat energy
Ground (or Pond) Source Heat Pump:  1 part electricity + 3 parts  
energy from constant temperature earth = 4 parts heat energy

Thus, the GSHP is twice as efficient as a condensing unit, and 4 times  
more efficient than electrical baseboards, towel bars, or radiant.

Yes, these can be expensive, especially if your drilling costs are  
high.  If your water well was expensive due to rocks, etc., then this  
probably won't be a good choice.  If you're moving a lot of earth and  
have the opportunity to bury horizontal coils under at least 6' of  
earth, that could save the drilling cost.  Pond loops are cheaper  
still, if you have a pond (one large and deep enough to take the  
heating/cooling loads).

Yes, these can be married with renewable energy systems, and this  
combo is considered the 'cadillac' of options.

We've only used this once, in an institutional building.  It's working  
great.  For any residential project it's been the first thing cut,  
even if the project wasn't over budget.  Investing in a better  
envelope (passive design, highest quality windows, insulation and  
weatherstripping) is the smarter expenditure, IMHO.

Cheers,

David Arkin


On Mar 18, 2009, at 10:16 AM, BuildersWithoutBorders wrote:

> Dear colleagues -
>
> Can someone shed some light on so-called geothermal heating systems,  
> and their cost-effectiveness for a typical home?
>
> I imagine the pay-back in energy saved has something to do with how  
> many heating degree days in a specific climate.  But then, I  
> understand they can also be reversed for cooling.
>
> This seems like an expensive technology that is dependent on  
> electrical service... can it be powered by solar/
>
> Thanks for any insight offered.
>
>
> Sincerely,
> Catherine Wanek
> Co-director
> Builders Without Borders
> <mail at builderswithoutborders.org>
> www.builderswithoutborders.org
> 575-895-5400
> _______________________________________________
> GSBN mailing list
> GSBN at greenbuilder.com
> http://greenbuilder.com/mailman/listinfo/GSBN
>


*  *  *  *  *
Arkin Tilt Architects
Ecological Planning & Design

David Arkin, AIA, Architect
LEED Accredited Professional
CA #C22459/NV #5030

1101 8th St. #180, Berkeley, CA  94710
510/528-9830
www.arkintilt.com

"There is no way to peace. Peace is the way."
— A. J. Muste