Manitoba GreenHouse

The Manitoba Greenhouse was developed by the University of Manitoba in the early 70's. its basic design is 3 insulated walls and south facing Glazing. and thermal storage area to moderate the greenhouse temperatures plus provide it with a certain amount security for cold winter nights. The Chinese adopted it design modifying it slightly . they use non insulated High mass walls.

here is some sample data of the greenhouse design daytime and night time temp comparisons under various conditions

It nicely moderates the greenhouse condition so it does not over heat to such an extreme as a normal greenhouse would.

In Manitoba depending on the type of glazing one uses and this type of greenhouse one can achieve a greenhouse that stays relatively warm all winter long with out any additional heat source.

Now my adaptation of the Manitoba greenhouse is similar. but it more along the lines of combining the Manitoba greenhouse version and the Chinese. An insulated wall and an internal secondary wall cavity that filled with soil which provides a high thermal mass. but on top of that I trench in x amount of ground loop ( usually the length is equal to the square footage of the greenhouse) at well below the frost line.. and i circulate the it with a small pump. It brings in cool ground water ( 10c) into a large 300 - 500 gallon tank usually flat rectangular in design so it has the most amount of surface area. During period when it is very sunny the high mass prevents the greenhouse from heating up to fast. plus the buffer tank takes some extra heat and moves it into the ground. but at night the circulating water brings in added heat into the green house to provide extra heat even on extended heavy overcast days when there is no solar radiation available to heat the greenhouse. Thus moderating the temperature even more so under the harshest of conditions. it works well enough that i can grow cool temperature crops all winter . cabbage . kale and even celery. albeit slowly as i do not currently use an added lights.. but come March and the sun intensifies everything up and growing very quickly.

Currently it is March 3. my onions and garlic are up and growing, my cut flower beds are up and in weeks time or so i should have fresh cut flowers. any day now my peach tree and nectarine tress should burst into bloom plus a bunch of other produce such as strawberries. and kiwis .. And yet it still -20c outside - and yesterday night was even a little brutal at -30c for a night time temerature