In the Growing Spaces dome greenhouses, they have you install common field tile under
the raised beds and it comes up near the top of the dome where a muffin fan powered by
a small solar PV module transfers some of the heat to the raised beds. The plants
keep a little longer when the roots stay warmer. You can see some of their ideas at:
http://www.growingspaces.com/
We will be adding our dome greenhouse after we build our passive solar earthship in
the CO mountains in a couple years. I plan to augment the solar heating by installing
hydronic tubing in a sand bed under the raised beds in the greenhouse and using a DC
magnetic impeller pump powered by a solar PV module to carry the heat of the solar hot
water panels (non-toxic glycol/water solution). In the middle of the greenhouse is a
300 gallon water tank to raise aquatic plants and to be a thermal battery in winter
and summer. I want to experiment with adding a few loops of the hydronic tubing in
their also. Many customers add wood fired Snorkel hot tub also. This is practically
the only way to get fresh tomatoes at 9,000 feet where year round frosts are not
uncommon sometimes. The earthships itself has minor greenhouse space in the south
side of the living area, but it stays warmer due to the large thermal mass of the
rammed earth bermed structure in the home.
Dave
_________________________________________________
David & Sheila Knapp
Winnebago, Illinois
http://www.geocities.com/renewables/
_________________________________________________
----- Original Message -----
From: "John Van Hazinga" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, January 04, 2001 6:39 PM
Subject: Re: [ecopath] Re: Thoughts for 2001
> Concerning plastic barrels:: I have bought greenhouse plastic from Northern
> Greenhouse Sales of Neche ND. In their cheerful catalog they claim to plant
> vining crops in full barrels down the center of hoophouses. If you want to
> start seedlings Jeff, this may not work for you. No matter what the theory
> I fail to see how half submerged water barrels will transfer much heat
> into the ground. With a compost thermometer one could try different set ups
> and measure. Before freeze up I framed the base for a 12 by 20 hoophouse
> and unloaded a pickup of cow manure compost into it. When inspired this
> winter I plan to cover it and try a row of half barrels down the center
> in early spring.
>
> The most ingenious greenhouse system I have ever read about is that of a
> Joseph Orr of Laramie , Wyoming, in May 78 Mother Earth News. His was a
> hot air collector that blew heat into wet earth heat storage below the
> greenhouse. It is an active system but the major components of the hot
> air collector , fans , foam insulation, pvc pipe , and the earth which was
> there to begin with were not overly exspensive considering the results;
> tomatoes and tropicals yearround in Laramie with no other heat. (Yes he did
> use electricity but as I understand fans are not particularly energy
> gluttons.) This system would not be needed in your balmy climate, Jeff,
> but for those of us with over a foot of snow and likely facing at least 2
> more months of the same it is attractive.
>
> I plan a 14 by 20 shed greenhouse on the sw side of my living room.
> Presently the area is sloped but averages 5 feet below living room floor
> level so that construction would start with an insulated perimiter
> foundation and then infilling with planting beds, heat storage,
> watertanks, rockwork to bring it up to desired levels. I am considering
> the above system and or a masonry system like used in the earliest New
> England colonial greenhouses . However, my woodshop takes priority this
> year and I only hope to start on the foundation to make more level sunny
> gardening space. vann
>
>
