Author Topic: Solar Hoop type Greenhouse 1 layer of film or 2  (Read 3419 times)

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petect

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Solar Hoop type Greenhouse 1 layer of film or 2
« on: January 27, 2013, 03:57:40 PM »
I'm located in Connecticut. And I'm trying to decide if the extra work and expense of building a solar  hoop house with 2 layers of film makes sense. I don't expect to be able to grow 12 months a year, but would like to extend the season as much as possible, and possibly heve a warm place to hang out on sunny days.

All of the nurseries have 2 layers with fans that blow air between the layers to keep them apart. But they have furnaces to heat them too (I won't), so I can see where the second layer could pay off, if it reduces the fuel bill. 
Any thoughts from you nothern greenhouse guys, and gals will be appreciated.
Thanks
Pete

Crispy

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Re: Solar Hoop type Greenhouse 1 layer of film or 2
« Reply #1 on: January 27, 2013, 05:54:42 PM »
Petect,

I have been considering a greenhouse as well, so I'm interested in what your plans are and what you've learned so far.

I have learned that many a hoop style greenhouses have succumbed to snow loads up north, so additional bracing in the winter is crucial.

As far as the second layer, any dead air space will aid in retaining what heat you have. Depending on what you intend to grow, the second layer may not be worth the expense. Most veggies will not grow much if at all between mid November and mid February as there's just not enough light.

If you have the space, a few 55 gallon drums painted black and filled with water will store enough heat to get you to the no growth point and if there is a freak early severe cold snap, drape some bubble wrap from the top of the barrels diagonally down over the plants to keep them warm.

The drums will also be a handy place to set your beer while your working on your tan in January  8)

Crispy
My hair is smoldering for a reason, that's why I'm here.

petect

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Re: Solar Hoop type Greenhouse 1 layer of film or 2
« Reply #2 on: January 28, 2013, 11:45:15 AM »
Hey Crispy

Well my thoughts at the moment - always changing- go something like this. 18-20' w x 30-40' long.
 I'd use it mostly to extend the seasons as you mentioned, although some of the cold weather crops might hang in a bit longer.

I will definatly devide it into at least 2 sections using plastic or plywood and put most of my assets into the part closest to the house to hopefully keep that part a little more comfey. It might all have a film covering, or I might use twinwall in the "high-end" section and possibly harvest some of the warm air for heating the house and do my beer drinking there.   8)

Snow will be an issue. I see a lot of film covered greenhouses on farms, that have a more pointed profile with steeper walls, for this reason. I also keep thinking about making the top section from corrugated plastic panels, and using film for the sides to help with the snow. It might be possible to make some of the panels so they can be raised as a vent to let excess heat out.

At some point I will be adding a Rocket Stove to keep seed beds warm, and put some BTUs into the mass.

That's it for now. I hope you read through the greenhouse post below - lots of good info.
Pete

stag

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Re: Solar Hoop type Greenhouse 1 layer of film or 2
« Reply #3 on: April 27, 2013, 10:29:00 AM »
HI! Pete. Here in Norfolk UK. I use two greenhouses to extend the growing season,without extra heat as this would not be cost effective with ever increasing energy prices.  I have used bubble wrap as used in packaging as an insulating layer under the main skin to good effect. I am considering building a glass frame inside the greenhouse ,kinda like a mini greenhouse in side a greenhouse.Inside this, I intend to use drums of water painted matt black as passive solar heat sinks and will be experimenting with getting a little extra heat and light from my wind turbine. Of course , the wind doesn't blow all the time,and frosty nights are usually windless. I am not sure how plants will react to24hr light for a couple of days followed by a few days of normal daylight hours. If they react badly, I will try just heat from the wind, maybe a 12v fan heater blowing warm air through a pile of bricks as a heat sink. Self sufficiency rules!  Pete.

dnix71

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Re: Solar Hoop type Greenhouse 1 layer of film or 2
« Reply #4 on: April 27, 2013, 09:54:23 PM »
Two layers gives you time to patch a leak or failing panel. If one panel in a single layer hut fails you lose all your heat quick and let in bugs and birds, too.