Setting up my solar greenhouse.

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stevelau1911
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Setting up my solar greenhouse.

Post by stevelau1911 »

I just set up my 7X7X12 greenhouse today the results so far(from my weather station) are at 5PM when its cloudy outside(71.4F, 73%humidity), greenhouse(81.2F, 86%humidity) and at 10:30PM outside(59.6F, 87%humidity), greenhouse(64.6F, 96%humidity).

Basically during the daytime even without sunshine the temperature will be raised by 10F and about 5F at night. The humidity inside the greenhouse is also usually about 12% higher. I'm using 80 gallons of water to store heat now and will add more if its necessary.

I'm hoping that these temperature differences will be larger when it gets colder, or whenever it gets sunny. With my results so far, my solar greenhouse should be able to prevent any winter damage on the bamboos inside at full water capacity without additional heating.
bambootony
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Re: Setting up my solar greenhouse.

Post by bambootony »

Hello Steve,
Did you get any photos.
I'm planning a green house myself..
Your discription sounds GREAT!!!
Is your Green house the temporary kind?
From Bamboo Tony
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va_highlander
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Re: Setting up my solar greenhouse.

Post by va_highlander »

stevelau1911 wrote:Basically during the daytime even without sunshine the temperature will be raised by 10F and about 5F at night.
Not necessarily.

The difference between inside and outside temperatures will also depend upon how much wind there is. On a cold, clear night, there will actually be some heat loss due to so-called black-body radiation, too. The difference you observed today is valid for today's conditions. In four months, those conditions will be very different.
Michael
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Re: Setting up my solar greenhouse.

Post by JeffreyDV »

I think you will find you will get a higher daytime temp differential in the winter than you are getting now. Unfortunately your night time differential may be higher as well.
Jeff
stevelau1911
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Re: Setting up my solar greenhouse.

Post by stevelau1911 »

This is a temporary quick set-up type of greenhouse, but it still works great even without any extra insulation. It literally feels like a tropical rain-forest when I walk in there with the sharp increase in temperature and humidity. I noticed some heteroclada shoots about 2inches tall that were not there before, literally overnight since putting them in the greenhouse. I'm not going to insulate the greenhouse too much yet because even in the mid 70s, the temperature inside is getting close to 90F.

These are some possible adjustments I can do to open the gap in temp differential especially during the night.
1) Install bubble wrap on the interior to keep heat stored longer, might need more than 1 layer.
2) Paint the exterior of the greenhouse with insulation glaze.
3) Add reflective foil to the north side of the greenhouse to trap in more heat from the sun.
4) Hang a few solar lights on the top of the greenhose if I can find one strong enough.
5) Add more water to the heat store by filling up the 2 (55 gallon drums to the top) and adding milk jugs, or buckets of water.
6) Cover the whole greenhouse with a few layers of painters plastic.
7) Place bags of tree leaves on the west, north and east side of the greenhouse to trap heat in the soil.
8) Close the ventilation windows on the side of the greenhouse.
9) Place a portable electric heater inside the greenhouse.
I could probably think of many more ways to improve the temp gap at night time, but my goal is to raise the night time temperature in the winter by 15-20degrees so that the soil inside the greenhouse never freezes.

Heres some picture of the interior
Image
Image
bambootony
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Re: Setting up my solar greenhouse.

Post by bambootony »

OK I have a question...
Would mulch on the floor increase or decrease the temp at say january 0 deg. F.
Thanks for the photos Steve,
Nice batch of potted boo there!.
40 miles N.E of st louis
stevelau1911
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Re: Setting up my solar greenhouse.

Post by stevelau1911 »

Thats one fairly important adjustment I left out. I'm definitely going to mulch the bottom of the greenhouse floor with something light such as tree leaves or grass clippings because that would increase the soil temperature inside the pots at night time when it may drop below freezing. I doubt it would make much of a difference inside the greenhouse itself, but by providing lots of insulation on every side except the south side and a wind block would make the greenhouse less susceptable to strong winds, snow and other conditions on top of warming the interior.

Another good aspect about the solar greenhouse setup is that I shouldn't need to water frequently despite temperatures rising into the 90s with high humidity when its 75F outside, since theres condensation at the top of the greenhouse which produces a steady rain whenever temperatures rise.

The only concern is that with full sun and 90% humidity, if its actually good for temperatures to get close to 100F.
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Re: Setting up my solar greenhouse.

Post by needmore »

The voles will appreciate the mulch & leaves :lol: I've heard plenty of horror stories about them feasting inside greenhouses/poly tunnels, I try to wait until late in the year before loading up and I also try to keep it plenty cold to try and dicourage them.
Brad Salmon, zone 12B Kea'au, HI
http://www.needmorebamboo.com
bambootony
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Re: Setting up my solar greenhouse.

Post by bambootony »

Hey Brad,
Those are some really GREAT tips!!!
I guess the main factor is keeping the wind off the boo????
From Bamboo Tony
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stevelau1911
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Re: Setting up my solar greenhouse.

Post by stevelau1911 »

I added 30 more gallons of water to my heat sink today and it seems like the temperature differential at night is 8F higher than outside(a 3F improvement). I'm hoping that means a 0F night time low in January would be brought up well into the safe zone, but if wind protection works so well, then plants in the greenhouse shouldn't need any further protection especially considering the pots are buried. :santa: I'll try laying a few bamboos sideways, or upright and covering them up with painters plastic just to see if the pots freeze.

My only concern now is that if the greenhouse is completely sealed all the time, wouldn't the carbon-dioxide content in the air eventually get depleted which would hurt photosynthesis? I'm not sure if gases can find other ways in and out of the greenhouse, but I'm only noticing positive results so far. My greenhouse is completely sealed off of any air flow from outside with no ventilation.

Theres also a huge temperature variance inside a greenhouse which I don't think is a problem. I'll get something like 60F-102F instead of 55F-79F
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Re: Setting up my solar greenhouse.

Post by moriphen »

Are you worried about high humidity and mold?
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Re: Setting up my solar greenhouse.

Post by stevelau1911 »

On a cold, clear night, there will actually be some heat loss due to so-called black-body radiation, too. The difference you observed today is valid for today's conditions. In four months, those conditions will be very different.
Based on my weather station data, it appears that the temperature differential is less on clear nights. It averages about 7-8F warmer on a clear night while as much as 12F on cloudy nights so my data has evidence that supports your theory.

It will be interesting to know what effect snow cover will have on the temperature :bigsmurf:
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Re: Setting up my solar greenhouse.

Post by va_highlander »

stevelau1911 wrote:Based on my weather station data, it appears that the temperature differential is less on clear nights. It averages about 7-8F warmer on a clear night while as much as 12F on cloudy nights so my data has evidence that supports your theory.
Not what I mean at all.

There are three ways that heat 'moves' from place to place: conduction, convection, and radiation. Conduction is like when you set a frying pan over heat and, in time, the metal handle gets hot. That's conduction, when the heat 'flows' from the hot bottom of the pan to the relatively cooler handle. It's the simplest transfer mechanism and usually the least important when considering something like a greenhouse.

Convection is the transport of heat by a moving fluid, like when a cold wind is blowing on a warm greenhouse. Some of the moving air is heated when in contact with the warmer body and then that slightly warmer air, with the heat it absorbed, is carried away on the wind. Except in very rare real-world cases, convection is almost always the most significant heat transfer mechanism, even in so-called still air.

Radiation, or more properly black-body radiation, is when heat leaves a relatively warm body via infrared light, like the heat you can feel radiating from a fire. Except in the case of a warm body radiating into deep space on a very cold, very clear and still night, effects due to radiation are generally very small, relative to other transfer mechanisms.
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Re: Setting up my solar greenhouse.

Post by dudley »

adding bubble wrap may indeed keep heat from escaping but it will also block some sun, reducing the amount of heat gained from that source.
leaves or mulch will have a similar effect. also glazing.
meteorology 101. sun heats earth, earth heats air.
thats why when you solarize(sterilize) soil you use clear plastic not black.
if you want to trap more heat try a flood light at the bottom of the greenhouse pointing at the ground.
"Plants are people just like us"
stevelau1911
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Re: Setting up my solar greenhouse.

Post by stevelau1911 »

Today's my first day with 1 layer of bubble wrap added to my greenhouse and it surprised me when the temperature soared to 108F when the outdoor sensor only read 76F so I had to open the door. There is still an 18.2F differential now, well after sunset which shows evidence that bubble wrap makes some difference. I think convection has been reduced quite a bit since it has to go through 2 layers now.

I think that the rate of sunlight absorption may have decreased a little, but the rate of heat loss has been reduced enough so that the greenhouse will heat up faster and hold the heat longer. My goal is to never allow night time lows to drop below 32F.
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