Solar thermal greenhouse prototype for cold climates

November 30, 2012
Written by
Greenhouse 365's first prototype has proven effective up to -34˚C. (Courtesy Greenhouse 365.)
Greenhouse 365's first prototype has proven effective up to -34˚C. (Courtesy Greenhouse 365.)
A prototype solar thermal greenhouse could allow growers in cold climates to harness the power of the sun to produce fresh produce year-round.

The GH365 prototype, designed by Leo Hunnakko, doesn’t look like your typical greenhouse, thanks to a unique design that allows Hunnakko to grow lettuce, tomatoes, asparagus year-round in Thunder Bay, Ont. His prototype greenhouse, located in zone 2A, has been proven effective in nighttime temperatures up to -34˚C.


Two four foot by eight foot solar collectors on the roof of the greenhouse capture the sun’s energy. When solar and water temperatures reach optimum levels, a heated glycol and distilled water mixture flows through a heat exchange unit. This unit is connected to a 60 gallon solar thermal hot water tank with electric back-up.


“The greenhouse incorporates a massive heat retention cavity that comprises the north wall which is filled with sand kept warm by solar heated water that flows through heat resistant tubing imbedded throughout,” explains Hunnakko, founder of Greenhouse 365. “This same heated tubing is used to warm the root zones on the planter tables as well as for radiant floor heating. The 1.5-inch thick dual pane, argon filled, high heat retention south glazing is positioned at an optimum 36˚ angle to maximize passive solar impact.


At 22 feet by 18 feet, the amount of growing space offered by the first generation prototype is small. The Generation Two version can be scaled up to suit various user requirements.


Hunnakko said the GH365 could extend the growing season and reduce the cost of fresh vegetables in cold climates, improve food security in remote areas and offer a greener solution with minimal electrical consumption.

For more, contact Delia, east coast director or Iron and Earth at  This e-mail address is being protected from spambots. You need JavaScript enabled to view it  


+1 #6 Zarina Assis 2018-11-06 22:04
Hi we are interested in the GH 365. We live in Calgary and would like to grow veggies throughout the year. I woul like to know the installation and maintainable cost. Your reply will be much appreciated. Thanks.
+1 #5 James McKinnon 2018-01-27 18:50
Hey, I live in Thunder Bay and would love to build one myself. Not sure I can afford it at the moment, but would love some advice or tips from your struggles.
+1 #4 Trace Hathaway 2017-09-10 00:23
I live in Alaska and I've been trying to design something like this but I'm sceptical of spending money and finding out it won't work here.
+2 #3 Barb Izard 2016-12-29 10:08
Interested in a greenhouse for bc please send details
+4 #2 Blair 2016-10-16 20:45
Good day folks,
We're interested in the GH 365 solar water heated system.
Please include any printable information and your email on how I can check out your system. We live in Whitehorse, Yukon Territory and would like to see more growing season potential.

Thank you,
Blair Kelsberg
+1 #1 Anna Pike 2016-09-26 10:55
I am interested in the GH 365 solar water heated system.
Please include in your email information on how I can purchase your system.

Thank you,

Questions or comments? Email

Subscription Centre

New Subscription
Already a Subscriber
Customer Service
View Digital Magazine Renew

Most Popular

We are using cookies to give you the best experience on our website. By continuing to use the site, you agree to the use of cookies. To find out more, read our Privacy Policy.