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Author Topic: new greenhouse planning  (Read 5203 times)

brian

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new greenhouse planning
« on: December 08, 2015, 12:03:23 PM »
Next spring I'm getting married.  Along with that, we are looking at moving to a house with more land (in the same area - Southeast Pennsylvania).  Wife-to-be fully supports my citrus hobby and I am planning on constructing a free-standing greenhouse at the new property.  I am hoping to be able to ventilate well enough to keep my trees inside year-round, planting most directly into the ground.  I'm not sure how realistic this is with 90+F summer high temps here.  I have just begun my preliminary research into this, so I still have a ton of unanswered questions.  I am thinking of something like this http://www.greenhousemegastore.com/product/ventmaster-30-commercial-greenhouse/commercial-greenhouses as the frame/ventilation solution.   I have an initial budget of ~$15-20k.  I don't have a particular size in mind, but I'm thinking at least 25'x50', which is about quadruple my current floorspace, and 15'+ tall, which is twice my current height.  I don't need to move my plants in the first winter as I will still have access to my existing winter greenhouse for the next year at least. 



I know that Millet has a substantial greenhouse in a temperate climate that I can use for inspiration.  I imagine others on this forum have some experience with these things also.  Some of the big questions I have are...

Glazing material:  If I remember correctly, inflated PET sheeting is the best in terms of cost and insulation, but isn't very durable.   Will PET stand up to snow load in temperate states?  I've been extremely happy with the dual-layer 8mm rigid polycarbonate that I use for my winter greenhouse, though I can feel the heat loss through it in winter.  I'm thinking 10mm+ if I go this route.   It isn't cheap, but is far cheaper than something like glass.  I haven't priced glazing a structure this large yet.

Ventilation: My winter greenhouse seems to be fine when buttoned up all the time.  That is, I have zero ventilation beyond whatever leaks out from cracks in the floors, walls, etc.   It doesn't seem to be starved for CO2 as I get lots of new growth each winter.  Is this reasonable to expect for a larger greenhouse or will I need to either ventilate in winter or provide a supplemental CO2 source?  I haven't had an problems with condensation yet.

Heating:  I believe natural gas is the cheapest heat source at the moment.  Would make sense to allow some of the exhaust gasses to flow inside the greenhouse to add C02?  Obviously you would need some kind of sensors to detect dangerous pollutants or CO2/CO levels.  But my understanding is that natgas & propane can be very clean burning if properly maintained.   

Cooling:  my winter greenhouse gets above 115F in the summer when it is empty and the plants are all outside.  Is it possible to keep temperatures reasonable with only natural+fan ventilation?  It would certainly be possible to have a shade cloth either year-round or in the warmer months only.  I'm not sure how much air conditioning would cost but I imagine it would blow my budget entirely and I'd have to rethink the whole project.  It gets humid in summer here so evaporative cooling may not be effective.

Extra insulation: I can feel that the main source of heat loss in my winter greenhouse is the polycarbonate glazed face.  I wonder if it is realistic to have some kind of insulation blanket can roll down at night over the roof of the whole structure - assuming there's no snow?  I could also have grow lights running at this time as supplemental light. 

Water: it looks like most greenhouses can support gutters, which means rain barrels are an easy source of water for plants.  In addition, I would run a water line & spicket out to the greenhouse.  I know that others are using water barrels for heat storage also, I should be able to do the same.

Millet

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Re: new greenhouse planning
« Reply #1 on: December 08, 2015, 03:40:54 PM »
I'll add some comments a little at a time rather than all at once.  The north wall of a greenhouse does not add any light to the greenhouse,  in fact north walls lose greenhouse light.  On my greenhouse, I covered the inside of the north wall with 1.5 inch silver coated polyurethane insulation board. I also taped the seams of the boards using the 2" silver tape.  This reduces heat loss during the winter and provides additional light by reflecting the sun's light back into the greenhouse.
Millet

cory

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Re: new greenhouse planning
« Reply #2 on: December 08, 2015, 04:24:30 PM »
Congratulations Brian on your upcoming marriage, new house and new greenhouse!  Very exciting.  I would love to have a large greenhouse like you are planning too.  My greenhouse is only 12' 16' so I can't provide much help beyond the basics which you have probably learned from your current greenhouse, but that experience you have gotten will help you with planning your new one.  From what I have read it is actually easier to keep the climate of a large structure more stable than a smaller one.  Good luck.  It will be interesting to read what others will recommend for your plans, and I am hoping to learn from them also.  One thing I would recommend you think about is how you could provide different environments within the structure in case you want to grow plants that need different temperatures and humidity levels.   I really can't do much with that in my small structure besides finding small micro climates.  I grow orchids and citrus in mine.  I would love to have at least a cool and a warm section to better accommode the orchids I grow that grow best cooler and warmer than I keep the greenhouse for the majority of my plants.  I look forward to reading about the plans as well as the structure's construction progress and startup.

Cory

Tom

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Re: new greenhouse planning
« Reply #3 on: December 08, 2015, 06:32:43 PM »
Congratulations on all the excitement that is upcoming in your life ! I will enjoy reading about it here because you are already way out of my league. Your situation is much different than mine but very similar to Millet. He will be an excellent resource. It sounds like you have a great start ! Bigger is better. I'd think a smaller greenhouse for plants with extremely different requirements would be better if possible. You have the citrus bug for sure ! I think the variegated minneola is the best looking citrus fruit. For my area Sasumas and Meyer lemons work best. With a year long greenhouse I guess anything is possible. Home grown pineapple would taste unbelievable I think ! Tom

brian

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Re: new greenhouse planning
« Reply #4 on: December 09, 2015, 02:37:30 PM »
Millet, insulating the southern wall is a very good idea.  I expect I will do this if practical.  I may have considerable choice in the direction of the greenhouse... would it make sense for the longer length to face north-south, or east-west?  I would think north-south would receive the most light in summer, but maybe not so much in winter (because of lower sun angle) when it is needed most.  I also may be able to build the greenhouse into a slope somewhat, so the rear wall could be partially underground and insulated in that way, or the whole thing could be a lean-to into a slope depending on the lay of the land.

Cory, yes I was thinking I may have a section for higher humidty and heat and grow some true tropicals.  I'm excited about this prospect.

Tom, rather than have multiple greenhouses I'm thinking of adding a polycarb wall or similar and having different sections as I mentioned above. 

I've done somewhat more research, I'm using GreenhouseMegaStore.com as a reference for now.  Most greenhouse kits are expandable, so I can start smaller and add space later if it isn't too difficult to expand.  However, it could be complicated if I need to get a new permit each time and add concrete footers or dig.   It is an option though.   There does not seem to be meaningful cost savings when buying larger sections at once versus adding sections over time, though perhaps freight cost if that is not included.

I ran through the heating calculators on www.littlegreenhouse.com and if I'm doing the calculations right the insulation advantage of 10mm versus 8mm polycarbonate may not be enough to justify the added material cost, especially if I may have to replace it every decade.   It looks like I definitely want polycarbonate, though, as PET film doesn't look sturdy enough and glass & acrylic are more expensive than polycarb for no clear advantage to me.

My current question that I have no good answer to is - How much ventilation is required to maintain reasonable midsummer temps?  It seems there are a few styles of ventilation:

natural: thermostatically controlled vents throughout the entire length of both walls and a ridge vent through the entire length of the ridge.  This is the design of the Ventmaster link above.
most expensive) 
fan-powered: vents on short ends of greenhouse, powered by fans.  Either a pair per end or the entire length of the short ends (minus doors)
fan-powered plus Active cooling:  (condensors, water-wall swamp coolers, heat pumps)

I am wondering how much is required in my climate.  I'm willing to do some labor twice yearly to simple remove wall segments or something to allow extra ventilation in summer if that somehow introduces huge savings versus a more complex ventilation option.  I was initially hoping that the cheapest option would suffice, but if I remember correctly Millet has both shade cloth *and* active cooling to maintain temps and he is in a similar climate to mine.  So perhaps he can offer advice on this portion.

Ventmaster design comes with PET sheeting roof but it looks like you could use PC instead


Ranger Series powered fan vents on ends instead of side/ridge vents


EDIT - found some great information on the PolyVent system the Ventmaster design uses:

"A second automated passive ventilation system is the Poly Vent from Poly-Tex Greenhouse Co. This system is a sidewall formed from a series of polyethylene tubes that are connected. When the tubes are inflated, the Poly Vent makes a tight-fitting, double-layer greenhouse sidewall. The inflation fan is controlled by a thermostat so when the greenhouse is warm, the fan switches to off and the wall opens; when the greenhouse is cool, the fan switches on and inflates the tubes thus closing the wall. This system has worked fine on research greenhouses at the South Farm for six years. Each wall is controlled by a separate thermostat, so staged control is achieved. This system is best for small greenhouses, up to 60-80 feet long; with longer greenhouses, wind and rain tend to move the tubes from their enclosure. This system is less expensive than fan ventilation, initially; but the tubes have to be replaced every 2-3 years so the system still has a recurring cost.

Contact us if you need an address for Poly-Tex. This has been a simple, reliable system in our use at South Farm. It is designed for straight sidewalls, but might work on a curved wall of a quonset. Remember, when the power goes off, the wall deflates and the greenhouse is wide open; this is quite a disadvantage during winter power outages! They do sell a battery back-up system."


On evaporative cooling:   Pennsylvania average summer afternoon humidity is 56% per http://www.currentresults.com/Weather/US/humidity-by-state-in-summer.php. 


« Last Edit: December 09, 2015, 04:00:01 PM by brian »

Millet

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Re: new greenhouse planning
« Reply #5 on: December 09, 2015, 09:49:34 PM »
Personally, of the two greenhouses you show I would purchase the second one (Ranger Series powered fan vent)  My greenhouse has two fans (similar as shown in the picture) on the north end of the greenhouse, and two vents on the south end. The fans are capable of totally replacing the entire air volume inside the greenhouse structure (32-ft. wide X 72-ft. long X 11-ft. high) every one minute. Before building the greenhouse I would trench a 3 to 4 foot deep foundation trench around the entire greenhouse directly where the structure will sit, and insulate the trench so that the soil inside the greenhouse is insulated from the soil outside the greenhouse.  Doing so cause the entire greenhouse soil to become a heat sink reducing the heat expense throughout the winter months.  Also insulate the side kick walls. The little amount of light that the side kick walls bring, is not worth the extra heat that would be required if they were not insulated. Almost all commercial greenhouses are always build on a north/south orientation.  If you bild a greenhouse on an east/west ornamentation the sun bends greenhouse plants to the south.  Insulate the north wall.   In my greenhouse I also have removable insulation that covers the south wall at sunset and removes at sun rise. Do as you wish about the greenhouse roof.  I chose to use Teflon coated greenhouse grade double wall air inflated PET, which gives the highest R value.  It does reduce some light, but because the elevation here in Colorado where I live is 5,440-ft. the sun intensity here is extremely strong.  Using Teflon greenhouse grade PET, I normally replace the top about once every 5 years or so. It normally takes about 4 to 5 hours.

Millet
P.S. With that greenhouse you can plant your trees in the ground, giving you and your new wife (and the neighbors) all the citrus you and your neighbors could ever use.
« Last Edit: December 09, 2015, 09:56:19 PM by Millet »

brian

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Re: new greenhouse planning
« Reply #6 on: December 10, 2015, 04:37:20 AM »
Thank you Millet.   

I am surprised to hear you are using PET.  I imagined it would not survive the weather there.  Do you not get hail?  Any puncture issues?  Does it build up snow & ice?  I will certainly give this a second look. 

As far as insulation goes, many of the prefab kits come with PC end walls and side walls, with PET or PC options for glazing.  If the side walls and north walls will be insulated, I may simply build them out of plywood and foamboard insulation rather than adding foamboard overtop of more expensive PC, wasting its transparency. 

"In my greenhouse I also have removable insulation that covers the south wall at sunset and removes at sun rise"   -   Is this insulation inside or outside the greenhouse?  Some kind of rollup fabric?  Is this wall less insulated than the inflated PET roof?

Millet

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Re: new greenhouse planning
« Reply #7 on: December 10, 2015, 12:10:32 PM »
Brain, your using the three letters PET I assumed you meant Polyethylene film?   I'm not sure what the "T" stood for.  The roof on my greenhouse is two layers of 6-mil. The greenhouse grade has a Teflon covering on one said of the film.  This protects the film from the sun's degrading of the film.  Yes, we do get hail, but most bounces off.  They make a polyethylene 4" wide tape to cover any holes or cracks in the film .  The south wall insulation on my greenhouse is put up and removed manually by me.  It is made from 4' X 8' polyurethane aluminum one sided insulation board. It takes abut 5 minutes to put up and take down.  The average humidity for my location is 51% mornings 38 percent 5-pm afternoon.  Average daily humidity is 48%.  Evaporative greenhouse cooling works fine on 95 percent of the days. - Millet
« Last Edit: December 10, 2015, 12:18:14 PM by Millet »

brian

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Re: new greenhouse planning
« Reply #8 on: December 10, 2015, 05:08:18 PM »
Yes, by PET I do mean polyethylene film.  I will do a cost comparison on PET vs PC next time I do heating calculations, in terms of material cost vs heating efficiency.  Thanks for the information.

It sounds like fan ventilation plus evaporative cooling pads should be sufficient for me.  I expect I will go with this design. 


Daintree

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Re: new greenhouse planning
« Reply #9 on: December 10, 2015, 10:49:05 PM »

Heating:  I believe natural gas is the cheapest heat source at the moment.  Would make sense to allow some of the exhaust gasses to flow inside the greenhouse to add C02?  Obviously you would need some kind of sensors to detect dangerous pollutants or CO2/CO levels.  But my understanding is that natgas & propane can be very clean burning if properly maintained.   

Cooling:  my winter greenhouse gets above 115F in the summer when it is empty and the plants are all outside.  Is it possible to keep temperatures reasonable with only natural+fan ventilation?  It would certainly be possible to have a shade cloth either year-round or in the warmer months only.  I'm not sure how much air conditioning would cost but I imagine it would blow my budget entirely and I'd have to rethink the whole project.  It gets humid in summer here so evaporative cooling may not be effective.

Hi Brian!
Heating and cooling are two things I deal with a lot here in Idaho.  As far as heat, if you use an open flame gas furnace, the by-product is water vapor. This helps me with humidity in our dry winters, but adds no CO2.
As far as cooling in summer, the biggest help for me has been a shade cloth on a frame about a foot higher than the greenhouse.  Having it laying on the greenhouse just traps the heat.  The metal frame stays up all year, and I put the shade cloth on in late May and take it down in early September.  I use a lot of fans, plus the shade, and my indoor temps never get as hot as outdoors.  I also have tropical birds that live out there, so I am always very careful with air breath ability and temps.
Hope that helps!

Millet

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Re: new greenhouse planning
« Reply #10 on: December 11, 2015, 04:01:10 PM »
There are two types of shade cloths for greenhouses - Black Shade Cloth and Silvered shade cloth.  I have used both and place them directly on the greenhouse covering.   Personally, in all the years that I have been growing in a greenhouse I have never known a shade cloth causing additional heat inside the greenhouse.  The reason to use a shade cloth is to cool a greenhouse.  Of the two, I prefer the Silver net (Aluminized net).  It is called AluminNet and can be found using a simple Internet search. The black net blocks sunlight, while the AlumiNet both blocks sunlight and because it is silver colored it also reflects the sunlight away.  AlumiNet  comes in different weaves blocking out between 30 to 70 percent of the sun's light, I use the 30 percent shade  weave.  Between the shade cloth and evaporative cooling, I can keep the greenhouse at nice 80-F on a 100+ F sunny day. There is also a white liquid spray shade paint that is sold .  It is sprayed on in spring, and washed off in the fall. - Millet
« Last Edit: December 11, 2015, 04:04:43 PM by Millet »

brian

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Re: new greenhouse planning
« Reply #11 on: December 11, 2015, 07:21:45 PM »
Thanks for the information Daintree.  I will hold off on an evaporative cooling system until it proves to be necessary.  I am hoping shade cloth + ventilation will be enough.

However, I think you are mistaken about the CO2 emissions of burning natural gas.  This absolutely produces significant amounts of CO2.  You may be thinking about Hydrogen which only produces water vapor.  I am also thinking about putting birds in my greenhouse.  How does it work out for you?  I'd worry about them destroying smaller plants.   And if you are running an unvented heater with birds living inside and have no issues that is encouraging in terms of emissions safety.

« Last Edit: December 11, 2015, 07:45:38 PM by brian »

brian

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Re: new greenhouse planning
« Reply #12 on: December 11, 2015, 07:41:31 PM »
I double-checked my heating calculations.  It looks like maintaining a 55F min temp with average lows of 27.5F for five months will cost ~$50/mo to heat @32cents per 100cuft of natural gas, which is what my local gas company (PECO Energy) lists as the current price for gas.   This is cheaper than I expected.  Given this, the cost savings going as high as 16mm triple wall polycarbonate is only ~$8/mo would never pay off in the lifespan of the panels. 

karpes

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Re: new greenhouse planning
« Reply #13 on: December 12, 2015, 06:50:26 PM »
 Millet
  Have you noticed a decrease in heating cost? I would think that the fuel cost would be much lower now.

Millet

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Re: new greenhouse planning
« Reply #14 on: December 13, 2015, 01:34:57 PM »
Karl, yes the cost to heat the greenhouse is lower this year.  My greenhouse is heated by propane.  Last year propane was $1.90 per gallon, this year it is $1.09 per gallon. - Millet

Millet

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Re: new greenhouse planning
« Reply #15 on: December 18, 2015, 11:59:49 PM »
Two or three 20" box fans should be evenly placed between the north and south ends of the greenhouse near the ceiling to blow the hot air back down to the growing area.  Besides heating the plants, it lowers the temperature differential between the inside and out side temperatures at the roof's glazing. Without the fans, the air temperature at the greenhouse roof is quite warm, and the outside temperature is very cold during the winter.  The greater the temperature differential between the inside and outside, the faster the heat is lost to the outside.  Ceiling fans save a lot of money.  During the summer months leaving the ceiling fans off helps keeep the growing area cooler, by letting the heat raise towards the top of the structure.  - Millet

Millet

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Re: new greenhouse planning
« Reply #16 on: December 19, 2015, 02:11:40 PM »
I just read an article where a company started a "greenhouse" produce farm, using not actual greenhouses, but growing inside ship (freight) containers using  LED lights instead of the sun. I am always amazed at human ingenuity. - Millet.

brian

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Re: new greenhouse planning
« Reply #17 on: December 19, 2015, 11:14:56 PM »
Yes, I saw the mention of air circulating fans in many greenhouse planning docs, sounds like a requirement.

And I was also taking a step back and considering that large barn/shed insulated to R30 with grow lights would likely be far more efficient than heating and cooling a solar greenhouse.  Controlling humidity would be an issue, I assume.  Its an interesting thought.  Keeping containerized trees in a lighted basement would even work.  Doesnt seem like as much fun, though.  Being in a sunny greenhouse is a nice feeling.

So, after doing more research in my area it seems natural gas is not readily available.  Most homes use propane or heating oil.  Both cost around 2-3x what natural gas costs, so all of the sudden efficiency matters a lot to me.  My new working plan is a quonset roof of 8mm PC, and a silvered "bubble wrap" pool-cover type insulating blanket that can be rolled across the round roof automatically at dusk and retracted at dawn.  It would need a manual shutoff for when it snows.  Trapped moisture could become an issue but pool covers are generally treated to retard growth.  The silvered material would also block light, so I could activate grow lights at night without lighting up the neighborhood.  The south wall would be something like 16mm triwall PC, and insulated north wall and sidewalls (and foundation) as you reccomend.  My only concern is that a quonset roof will hold snow while a gothic or gable shape sheds snow easily.  My current greenhouse face sheds snow very efficiently.  I cant envision a solution for an automatic insulating blanket that would work on a pointed ridge roof.  If anybody has and ideas Id love to hear them.  Mounting the insulating blanket on the roof peak doesnt seem practical, and pushing a soft material against gravity doesnt work well.  Perhaps having a wire and pully that pulls a cover up each face could work.

brian

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Re: new greenhouse planning
« Reply #18 on: December 19, 2015, 11:36:16 PM »
Actually... Maybe having the insulation blankets roll horizontally instead of vertically across each side of the roof could work with a pointed roof.  They could be mounted on the north face where they wont be blocking light, and I can access them with a ladder on that side in case of jams/debris/snow

Millet

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Re: new greenhouse planning
« Reply #19 on: December 20, 2015, 01:17:37 PM »
For 14 years I worked for a greenhouse chemlical supply company.  I called on greenhouse operation all of the western United States.  In all cases greenhouse ceiling insulation blankets are always on the inside of the greenhouse, never on the outside.

https://www.youtube.com/watch?v=m4lw7-_gYAI

Millet
« Last Edit: December 20, 2015, 01:54:09 PM by Millet »

brian

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Re: new greenhouse planning
« Reply #20 on: December 20, 2015, 04:39:23 PM »
Thanks for the video.  It is interesting to see how the covering is applied high up in the greenhouse, rather than straight across as I have seen other examples of.  However, the R-value of such a covering seems like it would be low compared to the type of cover I am describing.  I'm wondering if it would be possible to do a similar design with a heavier material.  A thicker material would be hard to roll at anything other than a straight angle.  And going straight across horizontally wouldn't work if my sidewall height is low... around 4ft I am expecting.  It would cut off most of the ceiling space.

Millet

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Re: new greenhouse planning
« Reply #21 on: December 20, 2015, 10:38:20 PM »
The thickness of the covering has a lot to do with the climate of the area.  The one in the video  was in Turkey.  The coverings in Colorado are quite thick due to the cold winters, and the need for good insulation against heat loss. As you wrote, there are straight  coverings as well as ones shown in the video.  In all cases no coverings that I have ever seen were rolled, they are pulled in each direction like curtains. See the black metal peaces at the end of each curtain section (shaped like a "V"), they are what gathers the cover and folds it up like a curtain.  Anyway just an example of what is used in commercial greenhouse structures. Your future greenhouse will certainly be exciting, both for you and us to follow. - Millet
« Last Edit: December 21, 2015, 09:49:41 PM by Millet »

brian

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Re: new greenhouse planning
« Reply #22 on: December 21, 2015, 05:29:53 PM »
Ah, yes.  I looked into the thermal curtain systems your video describes.. it seems that the pocket of air trapped above the curtain may be more valuable for insulation than the material thickness itself.  The only downside of this type of system that I can see is that it appears very expensive... maybe $7-8k for the size I am looking at.  This is enough to make an insulated non-transparent structure w/ grow lights seem more attractive.  I don't think I can replicate this type of thing on my own, either.

So, I'm trying to find a way to get the best of both worlds... that is a bright, sunny, clear structure in daylight and an insulated blackout bunker at night.  I was brainstorming for a while and external insulating blankets seem like the only workable solution I can think of. 

Investigating pool covers and bubble insulation I came across the many articles explaning how bubble-wrap type radiant barriers have nearly no R-value, and the R-value advertised is derived almost entirely from the presumed air gap created by the material and not the material itself.  So, I was thinking of a flexible material that would have an actual R value.  The only thing that came up in my search is "K-Flex INSUL-SHEET" which is closed cell foam.  However, it looks very heavy and is expensive... as much as an internal automated curtain system just for the material itself.  The cheapest insulating material I'm aware of is spun fiberglass rolls/batts, the same as interior walls are insulated with.   Of course this isn't weatherproof.  Sooo.... my somewhat crazy idea is to sandwich a layer of 2.5" R13 (thinnest I can find) fiberglass between two layers of plastic, of which at least one is reflective/blackout/radiant, creating a pair of giant ~18'x48' insulating blankets that roll up either side of a gothic/gabled greenhouse.  It would require a small reel at the peak across the length of the greenhouse, and a large reel on each side to hold the blanket during daytime. 

Aside from the effort of creating the whole thing, the big problems that come to mind are:

1) Wind blowing the cover off.  I think with the correct design this will actually not be a problem because it will be taughtly strapped into place on either end and connected to reels
2) Moisture - mold growing on the underside of the blanket, or water penetrating the plastic cover soaking the fiberglass.  This would make it far heavier, drastically reduce R-value, pretty much ruin the design. 
3) Friction between the insulating blanket and the roof while it is raised/lowered.  I know from experience that polycarbonate panels are very slippery.  Combined with a textured plastic like the bubble-wrap style radiant barrier this may not be an issue.  The screws used to secure the polycarbonate roof to the purlins and join the panels would have to be rounded to avoid jagged edges that would catch the plastic as it moves across.  If the blanket is wet, however, it may not slide well at all. 

This could give an incredible R16.6 insulation factor (.06 heat loss factor) for the roof.   For comparison, plain 8mm twinwall polycarbonate is R1.6 (.62 heat loss factor) and 16mm triwall is R2.5 (.42 heat loss)

anyway I'm still thinking about this as I have tons of time before I would begin construction.  Here's a mockup of what I'm describing...



I calculated the blankets of this design to cost ~$550 each to make so ~$1100 total plus the cost of reels, motor, timer, etc.  If it worked it could pay for itself in one heating season.
« Last Edit: December 21, 2015, 05:48:48 PM by brian »

Mark in Texas

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Re: new greenhouse planning
« Reply #23 on: December 26, 2015, 02:59:16 PM »
Here's mine, a Nexus Zephr.  10' columns, 18' peak, rainwater collection (later added).



Am raising cados, mango, pineapples, citrus, sugar apple and the usual stuff like maters, herbs, etc.

ILink 800 controller, http://store.link4corp.com/igrow-800-greenhouse-controller/   Locke 1 HP motors, Reznor propane heater, 4' tall guillotine wall vent on south wall, 2' rack and pinion on the roof.  Palram SolarSoft corrugated covering.  Here's a link - http://tropicalfruitforum.com/index.php?topic=7511.msg96609#msg96609

Secure the columns on top of an above ground concrete beam instead of in the ground or have them rusting at ground level like mine are now.

Cheers!


Good luck with your new bride and project.
« Last Edit: December 26, 2015, 03:09:42 PM by Mark in Texas »

Millet

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Re: new greenhouse planning
« Reply #24 on: December 26, 2015, 04:09:19 PM »
Mark, nice greenhouse.  I think Nexus supplies Reznor heaters no matter what type of greenhouse you purchase from them. I have a Nexus Alpine greenhouse, it also came with a Reznor propane heater.  I installed an additional 250,000 BTU propane heater, so now I have two heaters in the greenhouse just in case one of them should go out on a cold Colorado night. One set at 50-F and the other at 55-F.- Millet

 

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