Cohousing-L Mailing List: Re: Ground-source Heat Pumps

[Bryan Bowen (bryan]

Great article, thanks for sharing it, Sharon.

This line of thinking is important for all cohousing communities (the magic
of sharing). The outcomes will vary based on building typology, density,
climate, soils/groundwater, and local installer experience. We first looked
at this with Wild Sage (which ended up with shared boilers and solar
thermal) and Silver Sage (same outcome), but both were during early days
and I think we had some oversizing issues among other things. Both have had
discussions about how to transition to all-electric operations.

We've been able to design shared GSHP systems into a few more recent
projects: Heartwood Commons in Tulsa is using one ground source heat field
per triplex or four-plex due to system scaling and density, and CoHousing
Houston is using one shared system for the whole project. Rooted
Northwest will also receive the same analysis. Similar approaches can be
followed for PV, depending on local regulations and utility limitations.
We're hoping to have one electrical meter per project, these days, and no
gas.

That said, it's important to really do the analysis with an open mind.
There are instances where unit but unit systems are both more eco and more
affordable. Be sure to work with local mechanical engineers who really
understand these systems, multifamily, and the realities of building more
energy efficient buildings.

- b

BRYAN BOWEN    |    PRINCIPAL   |    AIA   |    LEED AP

*caddis collaborative*
1521 Easy Rider Lane #102
Boulder, CO 80304
303 443 3629
caddispc.com


On Thu, Jun 15, 2023 at 9:30 AM Sharon Villines via Cohousing-L <
cohousing-l [at] cohousing.org> wrote:

> Fast Company has a good article on a program in Massachusetts in which
> almost all homes are switching to geothermal energy. By doing it as a
> community they are saving a bundle on installation and will next save a
> bundle on energy.
>
>
> https://www.fastcompany.com/90907992/in-this-massachusetts-neighborhood-nearly-every-home-is-switching-to-geothermal-energy
>
> After our installation by a not to reputable company, we discovered that
> we were greatly over-installed. A major cost is drilling holes several
> hundred feet into the ground for the loops that move water down to where it
> is warmed or cooled to 55 or so degrees. The best installations use one
> loop for as many households as necessary — not one loop per household. In
> Massachusetts by converting whole neighborhoods to geothermal, they can
> install the best balance of loops for  “the block” and join them together.
>
> It’s very easy after having ground-source geothermal to forget how much
> money it saves us year-round. Now we have solar panels providing the
> electricity for the common house and outdoor lighting so it is essentially
> free. The maintenance and repair of the system is probably comparable to
> what we would be doing with any other kind if heat.
>
> But for 825 SF, with exposure on three sides including morning and
> afternoon sun, my electric bill is still in the range of $45-50 every
> month. That includes working at home, a set temperature of 74 degrees,
> washer/dryer, dishwasher, at least one screen on, and ceiling fans. Last
> year my bill jumped to $60 a month for no good reason, but I forgot to
> follow up and find out why. This year it went back down to $44 — ah! Error
> in calculating budgeted use.
>
> It was hard to pay upfront and we have learned by having one of the worst
> installations ever designed but in the long run it is been worth it. An
> office building near by had calculated that their new system would pay for
> itself in seven years but actually paid for itself in four. That was a
> number of years ago — I don’t know what current numbers are.
>
> Sharon
> ----
> Sharon Villines
> Takoma Village Cohousing, Washington DC
> http://www.takomavillage.org
>
>
>
>
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