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Greenhouse insulation...

medman225

Member
This will be less about tarp style greenhouse... and more about a structural greenhouse.
When your greenhouse night temps get really super cold, and you use a heater... is there no insulation for the glass/paneling? It just seems to me considering how thin the walls are, that it would take an almost constant heater being run, In say 40f cold night temps.
Same difference with air conditioner/cooling. Anything to combat this?(as putting something in between the walls, that lets the light in, and the buds, kinda defeats the purpose here... yet still, there's gotta be a better way than just heating/cooling endlessly til the temp drops/climbs again.

Thank you for your time in advance.:tiphat:
 

CrushnYuba

Active member
Yea. The glazing/film is what insulates mostly. All greenhouse covering has an r value. No one really uses glass. They use plastics. The best insulation is actually Air. Dead air space. Most common cheap cover is 6 mil poly. It's got an r value of about .8. Double layer poly with inflated gap is about twice that at 1.6 and so is twin wall polycarbonate. Triple wall polycarbonate is higher.

You would be surprised at just how good even single layers of 6 mil are. Insulates better then 2 inch thick lumber. Your climate dictates if you need more. As far as cooling, insulation makes no difference. you can't air condition. Solar gain makes it impossible. Ventilation is the most affective way of cooling.

40 degrees ain't bad. You can just bump that 10 degrees and you will do great.
 

Limeygreen

Well-known member
Veteran
You can install energy curtains which will create air pockets that hold temperatures in. When closed you can save around 40% energy if you go with a quality curtain. The humidity builds up so exhaust fans or being able to control the curtain to gap and allow air to leave works for this. This is how commercial glass houses conserve energy and it works very well, commercially a lot of people use glass for high light transmission, still double poly and poly carbonate houses choose to install curtains for energy savings as well. If you want to go the cheaper method you can get a thermal blanket and manually pull it but you still need to control your humidity somehow, curtains aren't cheap but can last ten years if you keep them clean and don't use harsh chemicals to clean them.
 

TheLoiteringKid

New member
YMMV but old trick for single pain windows, bubble wrap.
Mist water with a few drops of dish soap and lay the bubble wrap bubble side ageist the glass.
Used to have to do it to every window on my old house, heater normally would kick on and off every 15-20 min, with the bubble wrap it would take 40-60 min per cycle.
Has the added bonus of working like frosted glass for added privacy.
 

CrushnYuba

Active member
Bubble wrap is really good. Clear solar blankets for pools are the same but stronger and resist uv better. I have bubble wrapped plywood endwalls and sidewalls in winter in my hoops.
I have mostly built steel hoop style greenhouses, but a couple lumber and polycarbonate. For rigid "structural" greenhouses multi wall polycarbonate it's king. Glass just is outdated. Allot of people that have them are replacing the glass panels with polycarbonate. Even dual pane
glass sucks. It looks pretty but that's it.

Last winter i heated a 12x40 hoop with single layer of 6 mil from Around 40f to 60f for 1.60$ a night. This would have been much less of i wiggle wired the plastic to the baseboard. But i didn't feel like taking off the roll up sides. It would have been even less off i did double layer roof like usual.
 

Limeygreen

Well-known member
Veteran
How do you inflate it? Do you use power from your location and blowers with pressure relief valves? I have been thinking about low cost way of doing this, the amish in pen have used wind powered fans and drier vents to inflate, I had thought about solar panel but this could prove to unreliable without storage.
 

CrushnYuba

Active member
They are made For greenhouses. They are shaded pole blowers. No relief valves. They are small and it leaks slowly between the layers.

You can getter in ac or dc. I run them off solar bit it's a whole solar system that supports an off grid house. You could make a solar system for just thatt super easy and cheap. One battery but Greenhouses need electric anyway. Especially in winter. All heat sources need some form of electric except an old school wood stove and trust me, you don't want one in a greenhouse. You need fans for circulation. You need low powered lighting to keep from flowering.
 

MrMMJ

Member
I run a wood stove in my 24 X 100 steel hoop, but it's a sealed stove and draws air from a 4" dryer vent type hose from outside. ( Two 48" exhaust fans maintain negative pressure during the day, so if it drew from inside the ashes would get sucked out into the GH ) Keeps my propane Modine unit from cycling as often. Single 6ml cover. To keep it at 60 when it's in the 30's outside runs me $900 a month.
Got 5 yrs on this cover, will be changing to double inflation layer before this winter. Have a 24 X 30 that way, makes a difference!
I agree with Crushin , for a structural the double polycarb is good. I used some on my end walls.
Check out "rocket stoves" and thermal mass benches on ytube. One can be run outside with the ducting to heat a thermal mass running into the greenhouse and back out. I built a prototype and fired it up, burns like a rocket! Looking at setting it up as an automatic pellet fed rather than the small sticks used in most. Lots of stick and pellet variations on ytube of them.
Good luck !
 

CrushnYuba

Active member
Mr mmj. I think you were explaining your set up to me on my greenhouse thread. Maybe another one. Don't get me wrong. I got nothing against wood as long as it's a decent size gh. I only use wood and pellet. Just old school wood stoves without blowers not so much. If you got enough fans it will work, butgreenhouses needs electric.
My smallish greenhouses are all pellet. I am putting a Yukon polar furnace in a bigger gh for this winter. Its wood and oil/diesel. Just throw wood in and turn on the thermostat. Its huge and has auto air controls. Lights with oil, then if it runs out off wood in the am, it can burn oil.
They also make them in propane but i keep allot of off road diesel around for the generator.
 

farmerlion

Microbial Repositories
Mentor
Veteran
Medman25, Yes the end wall are thin. The air gaps are the insulation. I also place 2"x 4'x8' Styrofoam sheets on the floor then covered it with tile I re purposed from a building that was being torn down. I expect it to help greatly as the temps here will be -20f before my flowering has finished. I'm plumbing the greenhouse furnace to my main house propane tanks. I don't know how much more it will use. I think mid December should see the final plants harvested. I wish you well. At the Ace seeds forum here at ICMag. I have pictures of the building of my greenhouse. It should be the first few pages of the thread. (farmerlions first greenhouse grow). Hope it helps. Peace
 

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