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greenhouses

Walipini (underground greenhouse) panel help

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posted 5 years ago

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Hi Im new here. Im from Missouri and want to grow vegetables all year around. I plan on digging into the hill and having a tall wall in back and a short wall in front. Going to pour concrete footings, walls, and floor. I plan on having sun as heat for the day and I have an outdoor boiler and can pipe hot water heat to greenhouse for extra heat at night. Does anyone know what kind of insulated panels I should put on roof? I have called several places in my area and they are only familiar with regular greenhouses. Any suggestions are appreciated thank you.

S Bengi

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Location: Massachusetts, Zone:6/7 AHS:4 GDD:3000 Rainfall:48in even Soil:SandyLoam pH6 Flat

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posted 5 years ago

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Heater:
Plants like the extra CO2, so I would place the heater inside the greenhouse vs outside. The radiant PEX pipe heating sounds like a wonderful idea to warm the soil vs just the air.

Insulation:
I recommend insulating the floor and walls that are in contact with the soil. This would be with regular EPS foamboard, same as the ones used in houses.

Glass/Roof Insulation:
Normally the "glass" is not insulated. You could get a double pane/layer "glass", polycarbonate sheet or inflated poly-film. they do have some roll down "blanket" mats for a few Chinese style greenhouse but then you have roll them down and roll them up, and remove snow. Yes remove the snow, which to me just sounds like a type of punishment.

Iterations are fine, we don't have to be perfect
My 2nd Location:Florida HardinessZone:10 AHS:10 GDD:8500 Rainfall:2in/mth winter, 8in/mth summer, Soil:Sand pH8 Flat

Rob Evers

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posted 5 years ago

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Ok thanks a lot. If I did just a regular roof panel how much heat do you think would be lost at night??

Rick Stelter

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posted 5 years ago

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S Bengi wrote:Heater:
Plants like the extra CO2, so I would place the heater inside the greenhouse vs outside. The radiant PEX pipe heating sounds like a wonderful idea to warm the soil vs just the air.

Insulation:
I recommend insulating the floor and walls that are in contact with the soil. This would be with regular EPS foamboard, same as the ones used in houses.

Glass/Roof Insulation:
Normally the "glass" is not insulated. You could get a double pane/layer "glass", polycarbonate sheet or inflated poly-film. they do have some roll down "blanket" mats for a few Chinese style greenhouse but then you have roll them down and roll them up, and remove snow. Yes remove the snow, which to me just sounds like a type of punishment.

Have you considered a Beadwall system? Google it and Zomeworks.and It's somewhat technical, but the airport in Aspen, Colorado had one. It was fascinating to watch. 6 inches of beads is abour R-15..

Rob Evers

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posted 5 years ago

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I will have to check on that. Thanks. What size do you all think would be good. I was thinking of doing 16x40

William Bronson

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Location: Cincinnati, Ohio,Price Hill 45205

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posted 5 years ago

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I would be concerned with any heater that was adding significant CO2 to an enclosed space .
If you have an outdoor boiler already, I would stick with it, though I would make provisions for adding a heater to inside the greenhouse as well.

Insulation wise, consider including the soil around your greenhouse in the insulation/water barrier envelop.
This "umbrella" concept ties the soil to the house and vice versa.

Budget will affect size a lot , as will purpose.
Are you planning to grow for market or just for yourself?

Insulating the glass surface at night might be achieved with mats or blankets on the inside of the greenhouse.
I'm trying this with "shade cloth" inside my greenhouse right now, though I am not taking it up and down each night.

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Rob Evers

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posted 5 years ago

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Thanks and I’m just growing for our family of 5. But want to grow all year round. One place told me I could use two layers of poly with large air gap in the middle and a fan to blow between them to keep moisture down between panels. But I think I would like to try it with dual wall poly and heat it a little more. Any thoughts? And is 16x40 big enough for 5 people. And then grow stuff you can can in the summer in our regular garden

S Bengi

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Location: Massachusetts, Zone:6/7 AHS:4 GDD:3000 Rainfall:48in even Soil:SandyLoam pH6 Flat

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posted 5 years ago

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So there are 5 people and you each eat about 0.5lbs of leafy greens per day for 7 days, so 20lbs of leafy greens, every week.
I assume you will grow your root crops and herbs during the summer and store them elsewhere.
That 20lbs of harvest will probably take 50sqft of growing space.

Your Greenhouse is about 650sqft or 50sqft x 13. So if you were to simple think of the greenhouse as in-ground storage and start off the winter with them ready for harvest you would be covered for 3 months (13weeks).
Also bed number 1 of 13, that you harvested and replanted the 1st week will surely be ready for another harvest before week 13.
Unlike in the summer/spring it will probably take 10weeks vs just 5weeks, due to lower temperature and sunlight.
So by week 13 around 4 beds will be ready again for harvest. With all of that I would say that you should be okay for the winter.

I did however make quite a few assumptions, such as:
Winter Duration
Consumption/Week
Exclusive Leafy greens production vs root/seed vegetables
Greenhouse Soil Temperature

Iterations are fine, we don't have to be perfect
My 2nd Location:Florida HardinessZone:10 AHS:10 GDD:8500 Rainfall:2in/mth winter, 8in/mth summer, Soil:Sand pH8 Flat

Rick Stelter

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posted 5 years ago

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Rob Evers wrote:I will have to check on that. Thanks. What size do you all think would be good. I was thinking of doing 16x40

I think that is an excellent size. Not too small, which leads to tempature control problems, and not so large as to be too much to take care of in a reasonable amount of time.
You also may want to consider thermal mass to moderate temps as well.

R Scott

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Location: Kansas Zone 6a

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posted 5 years ago

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Not sure where in Missouri, but Farmtek is just over the border in Iowa and usually has huge discounts on twin wall panels in their scratch and dent. Usually they have an inch or so damage on one side from a forklift. They won't work in their aluminum frames, but work fine with wood frames and oversized trim.

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