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Greenhouse types for colder climate


(stephen krywenko) #1

For those who might be curious. I started temperature mapping my greenhouse,. and I have being quite pleasantly surprised by their performance… especially on this very brutal winter we are having this year
over the last 10 years I built a couple “different” styles for harsh environments… and I think I will build one more larger one this summer - they do not cost that much ~$1000 for 1000 sqf of greenhouse

Manitoba Greenhouse ( university of manitoba cira 1968)

is a insulate slanted wall greenhouse that is well insulated on 3 wall.
advantage - low energy input in cold climates . disadvantage over heating and cost…

Chinese Greenhouse ( china cira 1978 which was based on UofM Greenhouse )

it is similar in construction to Manitoba Greenhouse biggest difference is it is high mass wall greenhouse.
advantages - naturally temperature moderated and much cheaper then the Manitoba greenhouse to build. disadvantage- moderate energy input in cold climate.

in both greenhouses I use a “passive” geothermal type heating for every square foot of greenhouse i bury equal length of ground loop that will circulate 300 gallons of water through the ground loop into low temp 300 gallon heat sink in the greenhouse operating cost is 20 - 46watts per hour or average yearly cost of $15.

Screenshot_20190205_192855

here is the temperate gradient for the middle winter, even when it was -43c outside the coldest days of -43c the greenhouses did not cool that much to - 18C which means mostly likely I did not even loose 1%- 5% of my fruit buds on my most tender trees ( nectarines)
Screenshot_20190205_201840

I operate the greenhouse seasonally - the growing season for them is mid March to mid Nov which for me adds on 4-5 extra months of growing season. the Manitoba greenhouse since it is a much hotter green house i generally grow tomatoes and pepper in there as they love it in the Chinese greenhouse I grow - zone 4-6 fruit trees ( figs, peaches, nectarines Italian plums etc) in a zone 2-3 region since it temperature moderated better they prefer it there. and i must admit their nothing like a fresh picked nectarines in the morning :slight_smile:

each greenhouse style has advantages and disadvantages – but I think I prefer the chinese style… its over all growing season is about 1 month shorter then the Manitoba - but you get better growth due to less heat stress so it averages out to the same in the end for food production

but I you are thinking of year round greenhouse then a mixture of a Chinese and Manitoba greenhouse would be your best option which would entail building a Chinese greenhouse then wrap the exterior wall in 2 -4 in Styrofoam wall

(ps I know I spelt Celsius wrong I just have not corrected it yet :wink: )


(Dave Howorth) #2

Interesting topic. A quick search didn’t find anything useful online about the design of the Manitoba greenhouse, although I did find a little bit about chinese solar greenhouses. So a bit more detail about the design of your greenhouses would be useful, or a link to a description and/or some photos. How do you heat the water?

It’s interesting how the value of a greenhouse varies from place to place. Here in the UK greenhouses are generally used to keep temperatures above freezing, or considerably warmer in the case of some big commercial ones.

The temperatures inside your greenhouses appear to be more like the inside of my freezer, although that’s a lot warmer than your outside temperature. I’m surprised that nectarines are hardy enough to survive; I’ve always thought of them as tender, but maybe I can plant one out in my garden.

Have you come across solar bubble greenhouses? They have always struck me as a very clever way to both heat and insulate a greehouse.


(stephen krywenko) #3

Yeah i know you can not find anymore info on the Manitoba greenhouse on the Web it was basically whitewashed off the web around 7 years ago not sure why, but basically then, the internet was purge of alot on information… i am familiar with the Manitoba greenhouse it was developed by the University of Manitoba in the late 60’s when I was going to school they provided my school with a grant and built one as we lived north 51 lat… and they wanted to test in rural communities how well they worked in harsh environments.
the Chinese greenhouse is based on the Manitoba greenhouse so the look the same. the biggest difference is the wall construction the Manitoba is insulated r20 on 3 wall ( where as the Chinese are high mass) the Manitoba green house normally have a well insulated room filled with granite rocks with in the greenhouse. when the temp diff between the greenhouse and the heat sink is warmer or cool determine which way the air flow goes - the Chinese are passive design with high mass wall

when I build my Chinese greenhouses all i do is build an empty cavity wall then fill with loose soil preferably high in clay.

nectarines depending on the variety are reasonably hardy- if you can - get fantasia they are one of the hardiest nectarines good to -18c before fruit buds burn… and there is 5-10 % lose for each degree colder . and if peaches are your thing pf 23 flaming fury-- it fruit loss starts at -23C… death or hard bun back will occur around -32 - 38C

yeah it seams quite cold but this is quite the unusual year… very cold with very little sun. so my greenhouse are much colder then usually … normally the Manitoba one sits above zero for most of the winter ( with 2 weeks where it is sits below zero all the time …) i actually do not mind it getting colder then zero in the greenhouse. one – I am not going to install lighting to support winter growth… just last week was the fist time the sun intensity was strong enough to support active growth ( +30000 LUX) -two – it a natural way to control greenhouse pest such as spider mites – let them freeze out… much easier then trying to fight for control…

maintoba greenhouse

DSC05011

Chinese greenhouse
DSC05012

excuse the mess - you can see the that I use double layer of plastic which creates a 4" air gap . that basically takes the basically 1-2 R rating and increase it to R5-7 if I was to put a more layer then I can increase the rating significantly but you loose usable light intensity. also you can see the liquid filled buffer tank which just circulates it through a ground loop. rising the fluid temperature to 7-10C … which then moderates the temperature in the greenhouse either warming or cooling if I wanted i could of buried my lines deeper and a bigger surface area buffer tank then i could of kept the building above zero all winter at around 5C

there is more that I can do to the Chinese one to make more energy efficient such as insulating the large door to the hoop green house that connected to it - i use that greenhouse for growing sweet potatoes and stuff like that… if i did that it probably cut the difference between the manitoba and chinese greenhouse in 1/2 – I also suspect if I used an automatic solar blanket at night i could probably keep it near zero… I plan to build another one this summer so I might Incorporated that feature in to there . but instead on the outside of the building on the inside as my weather too brutal for an exterior blanket


(stephen krywenko) #4

this pdf is is basically the same as info . though they use earth tubes. i am not a fan of earth tubes. energy required is significantly higher. than ditch witching in some plastic tubing and an internal thermal mass is alot cheaper. then fans they have to use 300 - 500 watts of fan to get the same energy heat transfer as I get with a single circulating pump running at 46 - 96 watts…
they also list for Feb 19 that the internal temp will be +20 during the day and a night 0c ( with an external temp of -30C this is what i as generally observe by the last week of February first week of march as well my fruit tree all starting to bloom… already currently they are slowly pushing buds as they expand on days where the temperature in the greenhouse is warmer then 5C and if it was a warm bright winter they start to bloom in last week of January-- but i started keeping my greenhouse cooler for this reason so they are more likely to open in march… as January just too early not enough light to support growth


(ian) #5

Hi Stephen

This is really interesting to me as we are contemplating a poly tunnel but may now think again.

Do you have any detailed information on the Manitoba greenhouse?

Regards

Ian


(stephen krywenko) #6

hi there - I will try to find you more info, but like I said after the information purge* - finding it i is a bit hard. it was at one time quite easy to get info on the internet about it . Here an university of manitoba abstract on the the Chinese green house which the sort of merge the manitoba greenhouse and Chinese one together. and if you like more detail here the the Chinese abstract

but after using both types the chinese/manitoba hybrid one is the better choice as no air handler is required and you have more usable space .

Or if you like I can draw up basic plans. giving detail and rational if you like info if you like

  • purge - if anyone if wondering the great purge of information happened in Canada under the previous Harper government - basically any information publicly produced that had government funding was purged from free access on the internet . and given to an American company where as now you have to pay for the information

(stephen krywenko) #7

hi ian just for you I moved one of my temp sensor to the hoop greenhouse ( poly tunnel) that way it give you . and Idea on temp diff between the differing types… this poly tunnel is only using one layer of poly… but generally greenhouses would use 2 layer and then puffed with air to give a bit of R value in my area. ( for some reason one of my sensors stopped working ( but its done it a couple times already I think with cold contraction it looses contact as soon as it warms slightly it back on line working )
Screenshot_20190209_075532
purple- Manitoba , Red - Chinese , Orange - Hoop, Blue - Outside temp


(Paul) #8

I just found this article whilst trying to better understand the context of this discussion (and what the heck a Chinese greenhouse was), interesting reading even for those of us without green fingers.


(ian) #9

Stephen

Many thanks. This has really given us food for thought. I have realised an issue we may have in the south of England is overheating in summer. Also our plot is long and narrow and runs North-South. There is no power apart from 12 volt PV which we use for irrigation.

I am wondering if we should consider a thermal wall with hoops and have the greenhouse cover rolled up in summer and rolled back into place in the winter. There is another consideration in that we are on high ground about 100 metres from a cliff edge overlooking the southern part of the English channel. We can get terrific gales in winter. A few years back we shared a glass greenhouse with a friend. We had a cracked pane of glass in the end facing the sea. I foolishly removed it to get a replacement. Before the glass was replaced we had a storm. On my next visit to the plot the greenhouse was totally destroyed, glass and aluminium frame!


(stephen krywenko) #10

ouch that hurts –

I think the Chinese greenhouse would work well for you… they are not so prone to overheating as a normal greenhouse… and if you do as i do with geothermal loop heat sink you can moderate it even better… I tried one of these pumps for one winter just to see how it would cope it was okish but the flow was not quite high enough at 20watts if I live in milder climate it would of being fine for winter temp moderation. for summer temp moderation it more then big enough and easily run by a solar panel - 46w pump works fine for me winter.

how i generally build mine is level and lay out old railway ties as the foundation. then i build either 2X4 or 2X6 wall, sheathed with plywood or OSB inside and out, then fill the hollow core with surrounding soil ( usually push off the top soil and use the clay underneath that being pushed up and allowed to dry so that it is loose) sand is fine too but sand it quite fluid, clay once it settles is more structurally sound. not sure if you can get transparent woven poly - it very strong longed life good for harsh environments and can easily withstand Gale winds speeds… on my Chinese green house I tried a different type it basically normal 12 mill greenhouse poly the has woven bans of semi transparent strands in it … light transmission is better. then pure woven one but not nearly as strong but lets see how long it last.