warm grenhouses in cold climates, designs?

[Loph]

Well, we are moving back to canada in 1-2 years, and aside from getting our farm there setup with cold houses and such, we need at least one greenhouse that stays above 10C all teh time.

our cliamte isnt that cold, -10 is a freek cold snap and lasts no more than a couple days if we even get one. The biggest problem is that our climate does not STAY cold, it fluctuates a lot, which brings a whack of issues with things. -5C to +10C day temps are normal.


without having huge electric/propane heaters. what are some designs people have made to keep their GH warm. i have looked into earth tunnels and stuff, but they dont seem to rise it high enough. I dont mind supplemental heating, there is no choice, i just want to limit it as much as possible through good design, cause gasses wont get cheaper, and electricity (when creating heat) isnt that cheap either.

im not sure, but i think our climate is similar to London England, i think. I am in central vancouver island, BC canada....close enough to Nanaimo but not there.

[daiv]

Well one of the members on the East Coast of the U.S. posted probably the best setup in terms of similar situations. I can't remember exactly who it was. It is somewhere in the forum here. I think that was a gas heat setup.

Insulating with bubblewrap should help too I think.

[Buck Hemenway]

My inlaws are from just south of there - Duncan. I have seen the snow more than 2 feet deep and ice about 4" thick. Possibly a little more severe than southern England, more like southern Scotland.

It is absoultely beautiful there, even when it is cold.

One big issue is deer. They eat everything. You will need all of your creativity to keep them out of any open growing areas.

[Loph]

Small world, i used to live there as well....lovely area. There is a new tea farm staring around Duncan i wa told.

They get snow, just got over a foot i was old by my mom, but its not as common as other areas.

deer, ya...everywhere. but a greenhouse will be closed. as far as pests go i think rodents are the worst problem for a greenhouse after buggies.

anyone here have heated greenhouses?

the heat concern is for tropical plants more than cacti, so 10C is a pretty strict minimum.

anyone know which material insulates more for heat?

[Sulcofan]

My inlaws are from just south of there - Duncan. I have seen the snow more than 2 feet deep and ice about 4" thick. Possibly a little more severe than southern England, more like southern Scotland.

It is absoultely beautiful there, even when it is cold.

One big issue is deer. They eat everything. You will need all of your creativity to keep them out of any open growing areas.

I've never seen 2' deep snow or 4" thick ice here in the south of Scotland. More like Scandinavia, I guess or perhaps the Scottish Highlands.

I have relatives on Gabriola Island, just off the coast from Nanaimo. The climate is way better than over here, more like the north of France, with which it shares the same 49 degrees latitude.

[*Barracuda_52*]

anyone here have heated greenhouses?

the heat concern is for tropical plants more than cacti, so 10C is a pretty strict minimum.

anyone know which material insulates more for heat?

Loph, im gona be using a heated GH going with ventless propane heat and subfloor heating, im also gona be using a clear solar pool cover for insulating insted of bubble wrap. We get alot of snow here and zero temps all the time durring winter. But i wont know how everything goes till next winter as both my GH's wont be built till this spring, it was to late for me to build them this past fall befour our early winter hit..
But if ya get the chance and this is gona be for tropicals, go with sub floor heating, and another sorce of heating plus check into the solar pool cover.. You might find it all works good for ya. and there is ways to go about it all without killing the wallet. I posted some stuff about my GHs and how im building them plus also a thread about Solar pool covers here in the GH section...

Hope that helps..

[iann]

You can get triple-wall (and more) polycarbonate which insulates pretty well. The roof is the main thing to insulate.

I can't really judge whether you get worthwhile solar heating in winter, but in regions that do it can make sense to use solar heat storage methods. Mostly these circulate water through some sort of thermal store which may be as simple as large barrels of water or the ground. That probably wouldn't keep you to a minimum 10C though.

[Loph]

Fortunately we do have relatively warm days. the majority of winter are for sure above 0C. on our super cold spells of -10C the days are rather cool, they don't last. for those short lived cold strikes, secondary heat like propane or something wont be bad as it will be temporary. I should maybe say, though it isnt fully accurate, that the heat inside an unheated greenhouse will probably be above freezing all but maybe 2 weeks a year (outside not, but inside yes). so the temp will *probably* only need raising say 10 degrees.

i have been reading about water systems, and air systems. for those interested this is an interesting website: http://www.sunnyjohn.com/indexpages/shcs.htm it talks about using the ground as a heat sink, instead of water and using air and fans instead of water and pumps.


has anyone useds those portable oil radiant heat things sold in box stores? i had one a few years back in canada indoors. it had 600/900/1500 watt options which was nice, but doubt it could heat even a 20x20 kind of size.

using a low ball of 1500 watts for probably 24 hours a day during cold spells = 36KW. in my area 1kw=$0.09 (cdn) = $3.24/day = $97.2/month. that is -ok-, but a hundred bucks is a hundred bucks, and i really doubt that is enough juice to come close to heating a GH to 10C, never mind a standard 20x50' one... Has anyone heated a GH in cold weather with electric heaters? I am just not aware of how to calculate costs with propane type heaters, never used them. I am basing other energy costs from government studies on hot house productions, and wow that aint cheap. I will need at elast 1 20x50 as a bare minumim for my hot plants, but in reality should have 4 or 5 hot houses, then cool houses for veggies. I might sound cheap, but i want to have quite a few going, which is why i am trying to pinch pennies. that and the cost of living in BC is pretty darn high in my opinion, so just living aint cheap.

[Peterthecactusguy]

dunno if you have designed your system or not, but I am pretty sure that propane heaters are rated for how many BTU's they produce. I have ones inside my house that I scarped for electric heating because it's way cheaper.

I however have no idea how much it would cost to heat your whole green house with the electric heaters.

[Loph]

Yes, we have designed,more or less, but are always willing to change. we don't move back for a year or 2 so there is time to make changes. the way fuel has been going and the trend of humanity, i don't want to rely on fire as heat...electricity is going up in our area a lot, but i am now seriously considering investing in a big solar system to run our house and then that will free up some monthly change for heating bills.


right now going for double wall style hoops that will have under gound heat sink with air (avoiding water). there is no way around supplemental ehating to 10C in -10C ouside weather, but tryign to limit the amount needed...


what i thought was the curse of fluctuating daily temps before i am not thinking is good for heating the GH up for night time. often days are 5-10C in winter with 0-5C nights. usually, there are cold spells that last a few weeks at times, but not often.


Barracuda_47, any news on yours?

[*Barracuda_52*]

Barracuda_47, any news on yours?

Loph, we hope to start building by the end of April, depends on how our weather goes we still have LOTS snow on the ground, and our weather is normaly whacky durring March and all thru April, it starts warming up and then we get another freeeeeez snap with more snow, we have even had snow in May many times. But i cant wait to get to building..

[TimN]

I know there are all sorts of indoor grow operations in BC. Tomatoes and other vegetables. Someone there would know or at least have experience in that climate.

My guess is that a hot water heated slab would be the most efficient in the long run. During the day it acts as a heat sink and gets pre-heated for the night when heat is needed.

In any event you have to plan how to avoid it being really hot right next to the heater and freezing cold on the far side of the green house.

You can probably find some growers in BC and email them to see what they say. It's certainly an interesting challenge.

[Peterthecactusguy]

When I went back to visit my parents they had gotten some quotes on getting geothermal heating. It sounded interesting and I forget exactly how it worked but it was very expensive.

The floor heating sounds like a good idea, but I don't know much about it, frankly I don't got to worry too much about heating really. I make due for 3-4 months with heaters and an electric blanket. I have stopped using them all already!
Honestly I wish I could do solar power for my house, but it's expensive and I have no money.

[PoC]

May have mentioned this before loph, but if I had a decent amount of land I would be really interested in making large compost piles for heat generation. This guy got heated water from his compost by adding hose/tubing into the center as well as methane fuel from a digester in the center of the compost. I've also read that some people have made large compost piles underneath their greenhouse for extra heat and gasses as well.

http://www.youtube.com/watch?v=JHRvwNJR ... r_embedded

[Gallows]

I live in the Comox Valley on Vancouver Island and I keep my cacti in an unheated greenhouse. In the fall I let them become completely dry and then move them into the house in a cold but frost free area and let them become dormant until spring. I have just moved them back out into the unheated greenhouse this week. During the winter I lost four cacti in total Melos don't seem to like the cold. I could never afford the heating bills to keep the greenhouse heated all winter. Also by letting the cacti become dormant in winter encourages them to flower the following spring and summer.