30 Below Yet Able To Grow!
Not too long ago I heard (via the aquaponics list I belong to) about a very intriguing greenhouse design created by a farmer in Manitoba for the purpose of growing Chinese vegetables year round.
Apparently, even with winter temps commonly dropping below -30 C (-22 F), the montly bill for three greenhouses was an average of only $140 CAD!
So what is the secret?
Passive solar heating coupled with a specialized thermal insulation blanket (lowered in the evenings).
Here is some exerpts from a very interesting article describing the greenhouse:
The weather outside may be frightful, but inside the greenhouses of Wenkai Oriental Vegetables in Elie, Man., even on a January afternoon with a brisk wind tearing across the prairie, it’s a balmy 27 C.
With the bright sun coming through the single layer of six-millimetre-thick plastic that covers the structure’s southern exposure and tiny transplanted Chinese cabbage seedlings poking up in neat rows in the damp, rich black soil, it feels more like a beautiful morning in June.
Unlike most greenhouses, which are heavily dependent on expensive supplementary heat, mainly natural gas, Wenkai Liu’s operation runs on pennies a day.
“Even when it’s -30 C, we don’t have to use any heat to keep it warm,” said Liu. “Our design offers energy savings of about 95 percent.”
The three 100 foot by 23 foot greenhouses, which were built using a design that is common in China, store heat from the sun in a 15 centimetre thick, two metre high stud frame wall filled with dry sand, and covered on the inside with aluminum sheeting that has been painted black. The outside has a layer of fiberglass insulation covered with plywood.
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Liu, who has lived near Elie with his wife and two young children since 1996, built the greenhouses two years ago with the help of a $20,000 research grant from Manitoba’s agriculture ministry, and technical assistance from Shenyang University in northeastern China.
“I brought the technology from China to show people how to operate a greenhouse in winter and save energy,” said Liu, 50, who was born in China.
Before that, he got a master’s degree in agriculture from North Dakota State University and worked in Venezuela for two years as an expert adviser. He also grows Chinese vegetables outdoors on his 10 acre farm during the summer, which he sells at fresh markets and through a contract agreement with Superstore.
Be sure to check out the full article: System heats greenhouse on pennies a day
For those of you who are scientifically-inclined, I also highly recommend you check out this research article (PDF) describing the performance of one of these greenhouses: Winter performance of a solar energy greenhouse in southern Manitoba
In case you are interested, Liu apparently will sell you the parts (and perhaps the plans?) to build you own for $10,000 (CAD $$) or so!
Like Spin Farming, this is very cool indeed, and makes me truly realize what could be possible here in southern Ontario!
Technorati Tags: greenhouse, manitoba, solar heating, passive heating, winter greenhouse, energy saving, alternative energy, chinese cabbage, greenhouse plans, gardening, farming
Written by Bentley on January 26th, 2007 with
1 comment.
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#1. January 26th, 2007, at 8:09 PM.
Just one slight correction folks - as you can see in one of the exerpts, Liu did not actually technically design the greenhouse - it is based upon designs commonly in use in northern China.