I am building a greenhouse and could use some expert help

EDIT: I deleted the original posting because I have a LOT more relevant information about what I am trying to do.

Hello Everyone,

Let me start by showing you the foundation I will be dealing with. it is 16'x44', being previously utilized as a pig house.

http://p3ach3s.imgur.com/greenhouse_foundation#QVc6f

The pictures were taken at the end of September, before I had cleared off the other side of the foundation which is separated by a wall in the center. I know I won't be able to build anything ontop of it the way it sits now, so my plan is actually to just fill it with concrete and cap the entire thing so it is flat and level.

This is a google sketchup of the greenhouse. (I'm sorry, I didn't know you had to download google sketchup to view it in 3d. You can download the viewer, it's only 10mb).

viewer: http://sketchup.google.com/intl/en/download/gsuviewer.html

greenhouse: http://sketchup.google.com/3dwarehouse/details?mid=1a81c8002fa46ed4a512ca8efb10109b

It's a rough draft, and the shed attached to it will house fish tanks. I’m using pressure treated lumber for the entire thing, and triple wall 16mm polycarbonate. The roof vents shown are probably going to be replaced with wall vents, as I have read they are more efficient at moving air than roof vents are. I can also mount a fan on the wall much more easily than I can on the roof.I am planning to put an aquaponics system inside the greenhouse, and with my own experimentation, create a system that is as efficient for the space used as I can possibly make it. I plan to use plant towers and growbeds, deep water culture and possibly some other inventive forms of growing to utilize as much space as I possibly can. I will hopefully be able to feed my family of three and possibly work out an arrangement with some local buyers to buy the surplus.

I also have a unique opportunity with currently having "no floor" in my greenhouse. Awhile back, I came across a few videos that intrigued me that were done by permies, on the topic of rocket stove mass heaters. I'd like to create one that heats my entire floor, which will be insulated on the bottom. I’m going to need to find out a few things before I can create a stove that is going to work.
All the videos I see of people making mass heaters have a LOT of piping in them, probably more than 50% of the mass itself. I don’t think it would be economical or sensible to make 50% of the inside of my floor piping. The floor is 702sq. ft.  My guess would be the stove wouldn’t work that well with that long of a flue on it, if at all. I’ve been searching online for someone who’s actually accumulated some data on this thing, such as calculating efficiency and temperature of the mass. I’d love to find someone who knows how long the stovepipe can be before it stops working, or if putting too many bends in it would be a problem. Also, where does the ash accumulate in the stove? Does it get pulled into the ‘re-burn barrel’ or does it sit in the bottom of the J? I do plan on building one myself before I put one in the greenhouse, but it won’t be on the same scale if I go through with this floor heating plan.
Thanks for looking

Just a suggestion on materials and construction. I have a friend that just build a sun room that found over the course of a few months enough salvaged sliding glass doors to build almost the size you are talking about for free. He looked on Craig's list and found both these doors and a full wall of windows. If you have the time to start collecting doors and windows for free, the cost of lumber to build the supporting structure could be reasonable.
A site I like for projects like this is: www.builditsolar.com
kent

what are you planning to use this greenhouse for?  growing food plants?  aquaculture?  greywater treatment?  a warm place to hang around in over the winter?  housing critters?

my first instinct is to tell you to forget about that foundation for a greenhouse and use it for something else.  there are plenty of ways to build greenhouses without it.  maybe the uses you have in mind would work better with a foundation, though, so that advice isn't absolute.  and it would provide a bit of thermal mass, though probably not terribly effective as it's in contact with both the ground and outside air.

you might check out Mike Oehler's The Earth Sheltered Solar Greenhouse from your local library for some ideas.  you don't have to adopt his method wholesale, but it could spark some ideas.  the greenhouse portions of Eliot Coleman's Four-Season Harvest might be worth peeking at as well.

for materials: I don't know what your situation is, but if you've got enough timber at your place, you may as well use it to frame your greenhouse.  round pole framing isn't rocket science and it's sturdy if you don't get careless.  if you don't have your own trees, you might be able to buy suitable poles for cheap from folks thinning timber plantations.

another route to go is bent galvanized tubing for a frame.  you can make a cheap polyethylene hoop house this way, but it sounds like you're after something more durable.  double- or triple-wall polycarbonate also works provided the diameter isn't too small.  lasts longer than polyethylene, though it's quite a bit more expensive.  it also insulates better than most other glazing options other than really expensive glass.  or you could go with a peaked roof style instead of a hoop house.  more expensive, but that opens up the possibility of glazing with glass.  if you're wanting to use salvaged glass, though, I believe a wood frame would be much easier.

there's a thread on here that covers a few drawbacks to greenhouses, and it might be worth at least skimming it to avoid some silly pitfalls.

keep asking questions.  the more specific, the better.

well i tried something new with my greenhouse this fall, i moved it over the pex that is in the soil that goes from our furnace (wood boiler) to our house and our son's house..as when we noticed last year that there was NO snow on the ground where the pex was buried..so it must have been heating the soil enough to melt the snow all winter long.

fall garden up and growing in the soil of the greenhouse, so far haven't gotten the furnace going for this year..no need for it as we are in t he 70's yet this fall

Your concrete foundation looks great, remember it is the nature of concrete to crack and crumble, from what I see you have a really solid foundation worthy of putting a green house on. (It appears as if the stem wall has broken off on one side near the tree.  I would say chop down the tree and its destructive root system, and form and pour back the broken stem wall.)  I see a great opportunity to install radiant heat pex pipe inside a new 2'' pad on the existing concrete.  Perhaps you could join this system with a rocket mass heater, using the existing concrete as part of your mass.  Another thing to do is paint the concrete black and have some kick ass passive solar gain going on.  Depending on how permanent you want the structure to be, I see you building a functional green house in one day using saplings or plastic conduit to make a bent frame construction covered with plastic sheeting.  Use the stem walls to your advantage here, letting the springiness of the frame material hold itself in place inside the stem walls.  This might be a good way to go untill you get around to building something more permanent.  Cheers.

Farm-Tek has a good selection of greenhouse goodies.

Greenhouses are very specialized structures designed around what you're growing inside. Let us know what your plans for crops are.

Your foundation may or may not be useful. Many greenhouses are anchored to the ground simply with ground stakes, and possible pouring pier footers for the corners.

Will you have electrical available?

The cheapest greenhouses with durability is structural galvanized steel with 4' bow spacing. Don't bother with the PVC, fence post top rail, or electrical conduit designs, which cannot handle your snow loads. For glazing, glass is the most durable (70 years), expensive, leakiest, most heat conductive material. Polycarbonate (double wall or triple wall) is more insulative and is warrantied for 10 years. Polyethylene films are the cheapest and last 4 - 5 years.

Think as much about cooling as heating. Greenhouses have huge solar gains.

We can tell you more when we hear back from you.

NM grower is right, the best greenhouse is site designed and use designed.

a couple of links which might be of interest
http://www.themodernhomestead.us/article/Greenhouse+Basics.html
and  http://userpages.bright.net/~fwo/greenhouse/greenhouse.html

Here is the website of the guy who makes the tools for bending tubing into high tunnel greenhouses.  www.lostcreek.net

Pressure treated lumber for the greenhouse has drawbacks due to its toxicity. You will get condensation on it and it will drip toxins onto your food production systems. These toxins will concentrate in a line along your cross members. You might think that's tolerable, or you might think that's to be avoided. Personally I'd avoid it. The US national organic standards prohibit any pressure treated lumber, so if you are planning on selling anything as organic, you'd be out of luck. Steel might give you a little extra zinc, from the galvanizing, but not much else.

I looked at at the sketchup model, and you are going fry in there. You need way more ventilation. Make the structure as tall as possible so you have a larger air mass to work with. First time greenhouse designers spend all their time thinking about heating and making a small enclosed space that is easier to heat. Second-time greenhouse designers spend much of their time thinking about cooling the structure and having increased space for crops and buffering the climate.

You should consider creating a 100% passively ventilated structure rather than relying on fans for your cooling. Unless you have your heart set on making all those angle cuts to create a quonset hut, I'd really recommend going with a shed-roof profile. Easier to build, easier to capture the roof water, easier to ventilate, easier to grow tall crops such as your towers, vine crops, etc. For passive ventilation you want a large top vent at the ridge line that runs the entire length of the greenhouse. And you want the same on both sidewalls, to bring cool air in. You want the top vent to open away from the prevailing winds so it acts as a thermal chimney siphoning the warm air out of the building.

Finally I would really like to encourage you to hire a local consultant who has extensive experience in building and designing actual greenhouses. You could use this person just to review your plans and still build everything yourself. This is all highly specialized knowledge. Passive solar residential architects think they know how to build greenhouses, but they do not. Pause for a moment and ponder if architects don't know how to design these structures, then just how time and money saving some expertise could be, compared to giving it your best shot first time out on your own.

Kind of looks like the orginal poster didn't come back.  FWIW here is our site, with lots of pictures of the dairy barn that we turned into a 4,000 square ft. greenhouse.  I had help on the construction for a day, the rest I did by myself.  If you are still around I have a few comments on what we've learned going into our 5th year.

http://luckydogfarm.wordpress.com/

Ed

Hey Ed, the OP is around, and just keeps editing the opening post to keep the relevant info at the top. You can see at the bottom of the post that the last edit was 1/21. Oh and regardless, lots of folks would benefit from hearing your thoughts 5 years after your barn --> greenhouse retrofit. So tell us!

Hey Paul:  Without reservation I would say stick with the concrete floor for your greenhouse.  When we were originally cleaning the place out, one of the days was -11F with a good wind blowing.  I would dig through the piles of 15 year old manure and find the bottoms soaking wet.  That floor never really gets too cold.  We tried insulating down 2 feet all the way around but there was just too much rock from the foundation.  It was -8F last night, 20 in the greenhouse and 26 under the second layer which is just above the plants we have in there.  Soil because it is on growing tables on top of the old cow stalls will freeze but thaws as the day warms up and the plants are not the worse for wear.  Lots of things wrong with the gh, in particular the angle of the twin wall.  Should be alot steeper but we didn't have time or money to deal with it, but will change it all this year or next.
On the summer heat, we remove 5 4' x 4' panels sometime in May, and just leave them off for the summer.  We can grow hot weather stuff in there for the summer.  This year we are going to put in a simple misting system and cover the whole thing with 50% shade cloth and dry to grow greens in there. 
The single biggest benefit to the concrete floor, besides the heat,  is it keeps all that moisture from seaping up into the growing space.  I have had traditional gh and the moisture has a tendancy to rot just about everything.  We also use the gh house to dry herbs, cure our garlic and onions which would be difficult without the dry conditions.
The one problem we haven't solved and we would love advice on this is how to get more CO2 into the environment.  Read some stuff recently the shows keeping the CO2 levels up will make up for alot of the lack of sunlight from mid Nov to the end of Jan. 
Ed

Hi Ed,

The shade cloth will surely help  in the summer, and let me recommend you use the reflective, aluminized  type. It is much more effective than the dark shades you typically see, such as black and green. Here in the high, bright southwest US I have measured a 14 degree F temperature drop from aluminized 50% shade cloth. (The brand I use is called Aluminet, there may be others.)

I bought a piece in 2002 that is still doing great. I store it away in the winter and use it from the first week I can't keep the greenhouse temperature below 86F (30C). Then I leave it on until danger of first snow. People will try to sell you seaming, edge taping, and grommets, but none of that is worth it to me. I just use plastic snap-close grommets and have never had a problem. The fabric does not unravel.

I am a little dubious about whether CO2 is limiting in your particular situation of greens production, based on what I've seen for pictures on your blog. In heated greenhouses that are tightly closed up in winter with massive growing biomass, such as a tomato house with rows of 8 foot high plants, yes it would be a factor. But you have a relatively small amount of respiration going on in there relative to the air volume, and you are probably not keeping the temperatures high enough for this to be a factor.

You could actually measure it to be sure. You'd sample the air next to the greens on a bright cold day when the greenhouse had been sealed up the whole time. Since you likely don't have the tool for measuring CO2, you might have to ask around to borrow one. Anyone who does modified atmosphere produce packaging would have a gas headspace analyzer that would give you accurate results.

Anyway, probably the best way to up CO2 and heat would be to build big compost heaps under the greens benches. The compost would give off lots of heat and CO2. I've seen an off-grid greenhouse that did all its germination in wooden flats sitting on top of compost rows that were 4' x 4' x as long as the greenhouse.

Other low tech means to increase CO up to atmospheric levels would be circulating fans so your greens have the slightest amount of leaf movement happening. Plus a heat exchanger and bringing in some outside air into the space. But if you have a leaky greenhouse, you might have air exchanges happening passively all over the place.

I suspect that soil and air temperature are your limiting factors. Maybe some thermal mass under the benches would help? Added heat from the compost? Better nighttime insulation?

Wouldn't mind a reference to the CO2 supplementation stuff that you were reading.

my understanding is that enriching CO[sub]2[/sub] can increase photosynthesis at moderate temperatures and light levels.  I've also read that it allows photosynthesis to continue at both higher and lower levels of both light and temperature than at ambient CO[sub]2[/sub] levels.

and enriching CO[sub]2[/sub] at night would be counterproductive for most plants.  except for CAM plants (Crassulacean acid metabolism), which take up CO[sub]2[/sub] at night so they can avoid water losses during the day.

for folks who are interested, enriching CO[sub]2[/sub] works because RuBisCO, an enzyme that binds with CO[sub]2[/sub] to be used building starches/sugars in the Calvin cycle, preferentially binds to O[sub]2[/sub], which wastes energy through photorespiration.  elevating the CO[sub]2[/sub] level allows RuBisCO to bind with more CO[sub]2[/sub] instead of O[sub]2[/sub].  there's some complicated biochemistry involved that I won't pretend to understand completely, but I hope that's a relatively accurate summary of the main idea.

if I were trying to increase CO[sub]2[/sub] in a greenhouse, I would use animals and yeast instead of compost.  chickens put out a substantial amount of heat in addition to CO[sub]2[/sub] and very useful shit.  they'll also potentially eat pest insects if a method of protecting the plants is arranged.  quail would be less destructive of plants than loose chickens, and still eat up insects.  using some of the stalls in Ed's greenhouse for larger animals would work, too.  and a wide variety of alcoholic beverages or fuels could be fermented in a greenhouse.  being warmer in the greenhouse would accelerate the activity of the yeast, thereby increasing CO[sub]2[/sub].  for a greenhouse the size of Ed's, a lot of critters or booze would be involved to make a substantial difference, but I don't think that being a little leaky rules out enrichment.  CO[sub]2[/sub] enrichment has been used outside at ground level under plants that form a relatively closed low canopy.  of course some of it dissipates into the wider environment, but not before quite a bit is used by the plants.  that it will leak out of Ed's greenhouse doesn't mean that it will leak out fast enough to evade all those greedy stomata.  obviously, the more plants that are in there, the more likely the extra CO[sub]2[/sub] will be used.

Once the first batch is done fermenting, we should all go over to Ed's and see how it's all going! 

I have often encountered the idea of integrating animals with the greenhouse, but I've never thought it would make sense for CO2 enrichment. The animals are outside foraging during the day, precisely at the time when you'd want to lock them in to make CO2 for the plants.

Has anybody measured the ppm CO2 of chicken breath?!

NM Grower wrote:
Once the first batch is done fermenting, we should all go over to Ed's and see how it's all going! 

sounds good to me.  it would have to be some brew, though, if I'm going to make the trip.  or some greenhouse.

NM Grower wrote:
I have often encountered the idea of integrating animals with the greenhouse, but I've never thought it would make sense for CO2 enrichment. The animals are outside foraging during the day, precisely at the time when you'd want to lock them in to make CO2 for the plants.

absolutely.  over the winter, though, our critters don't have much to forage anyway, so I'm sure they would be happy to stay inside and warm.  certainly a good point for during the growing season, though.

NM Grower wrote:
Has anybody measured the ppm CO2 of chicken breath?!

I sure haven't, but I bet someone has.  another good animal to keep in a greenhouse is humans.  I read a terrible book about the biodome, and I recall that high CO[sub]2[/sub] and low O[sub]2[/sub] levels were an issue.  and they had a huge greenhouse with a huge number of plants growing.  leads me to believe, with little to no hard evidence, that critters can have a significant impact on CO[sub]2[/sub] levels.  could also mean that humans are very sensitive to relative levels of those two gases in the air we breath.  I just don't remember.

and on the fermenting idea: haven't tried it yet, but I would fill up a balloon with the CO[sub]2[/sub] overnight, then let it out during the day.

Storing the CO2 for use the next sounds like a good idea, but the volume to have an effect might be enormous. I've toured a large dutch tomato greenhouse (100s of acres under glass), and they pump the flue gases from central boilers to the tomatoes. All day long they heat and store water in order to produce the CO2 from the burning of natural gas. Then at night they use the hot water in a radiant heat system to heat the tomatoes. They even have a movable pipe that they keep at the same level as the tomato clusters they are ripening.

Regarding the biosphere II project, I suspect a major CO2 source was the decomposition of the fallen leaves, spent crops, etc.

The Ministry of Agriculture for Alberta had this to say about CO2 supplementation:

"Attainable target yields for new growers for beefsteak and cluster tomatoes are between 50 and 55 kg/m2 of production area. Top Alberta producers have attained over 60 kg/m2 and over 70 kg/m2 in the research production greenhouses at the Crop Diversification Centre South at Brooks. Increased yield comes with increased grower experience and expertise, but the largest incremental yield increases attained by experienced growers comes through the adoption and use of new technology. The skilled use of computerized environmental control systems, newer, taller greenhouses and efficient cooling systems all help to increase yield. The use of carbon dioxide (CO2) supplementation has the potential to increase the yields of a skilled grower who now attains between 55 to 60 kg/m2 , up to 70 kg/m2 .

Recognizing that higher yields are always generally better than lower yields and that yield potential is constrained by a growers ability to control the greenhouse environment, it must be recognized a top-of-the-line greenhouse with all the bells and whistles, which results in a 70 kg/m2 crop, costs considerably more than a greenhouse with a few less bells. A 50 kg/m2 greenhouse can be as profitable as a 70 kg/m2 greenhouse when capital and operating costs are factored in. Technical improvements should be planned to compliment the skill of the grower and the financial means of the business. It is no use to focus on a new CO2 supplementation system if you are not optimizing the rest of your operation. For the CO2 system to pay dividends a grower must be running a finely tuned, top yielding crop with the current greenhouse." --- http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/opp7556

And interestingly, it looks like humans are better able to deal with high CO2 than are plants. Argus, who makes greenhouse control systems, has this to say:

"Plants are generally much more sensitive than humans to sustained exposure to high levels of CO2.
At levels exceeding 1000 ppm, young tomato plants may exhibit foliar inrolling and increased purple
pigmentation, and cucumber leaves may be burned or bleached. In general, supplementation beyond
800-1000 ppm has not been shown to be beneficial or cost effective for most greenhouse grown crops.

Human breath contains about 40,000 ppm CO2, or about 40 times the maximum sustained exposure
level recommended for plants, so humans have a far greater tolerance to CO2 concentrations. However,
acute human toxicity occurs at about 100,000 ppm, and above 50,000 ppm, people may experience
dizziness and loss of consciousness. Prolonged exposures above 20,000 ppm should be avoided." --- http://www.arguscontrols.com/articles/safe_co2.pdf

I might be about to let my ignorance show, but are the 'parts' in these 'parts per million' mass, volume, or molecules?  might not make a huge difference, but I'm curious.

NM Grower wrote:
Storing the CO2 for use the next sounds like a good idea, but the volume to have an effect might be enormous. I've toured a large dutch tomato greenhouse (100s of acres under glass), and they pump the flue gases from central boilers to the tomatoes. All day long they heat and store water in order to produce the CO2 from the burning of natural gas. Then at night they use the hot water in a radiant heat system to heat the tomatoes. They even have a movable pipe that they keep at the same level as the tomato clusters they are ripening.

so carbon dioxide is around 0.039% of our atmosphere (again, I don't know by what measure that is).  I did a rough calculation of how much CO[sub]2[/sub] a five-gallon carboy of a typical mead would produce over a fast two-week primary fermentation.  ends up with a little under 20 cubic feet of CO[sub]2[/sub].  being conservative, that would be maybe .5 cubic feet in an average 12-hour night.  that would be enough to double the ambient concentration in a 1282-cubic foot space (assuming the 0.039% is by volume), at least momentarily, and is about what would fit in a plain old rubber party balloon.  also consider that I'm not including the gas given off during the other 12 hours of the day.

1282 cubic feet isn't a huge space, but doubling the ambient concentration also isn't necessary to make a difference.  and that's just five gallons of medium-strength mead.  all this is to say that I think it could increase growth rate enough to be worth the effort, though probably not enough to blow anyone's mind.  since it doesn't require any extra equipment or expenditure, it makes sense to try it out, supposing the person involved already ferments.
(criticism of my maths won't be taken personally)

maybe the plants would use up that CO[sub]2[/sub] faster than it could be produced, though, in which case ventilation would probably be a more effective way to help the plants breathe.  I sure don't know.


back to the critters: a similar calculation for chicken breath will have to wait, but my working plan is to put a black soldier fly setup in my greenhouse.  larvae don't have to go anywhere to browse, as I'll be bringing the food to them.  the bin for the maggots is under construction.  the greenhouse only exists in my head.


of course, keeping the CO[sub]2[/sub] where it counts becomes more difficult if cooling the greenhouse involves frequent air exchanges.  I bet it could still be done, though.  wouldn't be too difficult to plumb a pipe that leaks fermentation gasses directly onto lettuce seedlings, &c, either out of a balloon or directly from the fermenter airlock.  sort of what your Dutch greenhouse was doing, only on a more reasonable scale.  the same could probably be done with creature breath, though it might take some creativity to avoid any accusations of cruelty.

other critters for CO[sub]2[/sub]: fishes.  a pond in a greenhouse has the potential to cause moisture problems, but careful design ought to prevent that.  and ponds can be so very, very productive.  and they're good for moderating temperature.

The info I have is from Mike Oehler's book.  He references a study done by Colorado State University.  I won't go into all the ppm that he references, but the following are results of a test that was done with cukes.

60% shade              64% yield
Full sunlight              100% yield
60% shade + CO2    92% yield
Full sunlight + CO2    147% yield

I think the whole idea of animals in the greenhouse is a great idea.  We sell our greens though and there is a certain level of cleanliness that we have to maintain.  Have looked into the solviva solution and lots of other ideas but for us if we wanted to boost production it would have to be something like a gas stove.  At solviva they mainly used the animals for heat, their poop gave off too much nitrogen which was harmful to the plants (been a long time since I read her book and I think it was nitrogen.) which is why she had to pass the air from the animals through an "earth filter" which isn't much more than peat moss.  Now, if you are doing this on a small scale, and you are raising chickens a great idea I read about was putting the starters under your growing beds.  The heatlights will warm the chickens and warm the roots above.  You have to keep them under lights for a long time, so it's a great way to kick your spring off.

Tel, what temperature does mead need to ferment?

Paul, thanks for the shade cloth tip.  Cheaper is not always better.  First seeds are coming out of cold stratification.  Edelweiss, Sea Holly, Pasque flower are up and doing well.  Don't know how I ever did what we do without propation mats.  Looks like the best investment dollar for dollar that we have made on the farm so far.

In an older book I have  about greenhouse gardening ( Gardening Indoors Under Lights,  Frederick H and Jacqueline Krantz) a couple of things were mentioned..the content of CO2 shouldn't be over 5% or "a lot of damage could be done" and the effect of CO2 on plants was originally spotted by someone wanting to see the effect of dry ice in greenhouses.

This may or may not be useful for anyone but in case anyone has a free supply of dry ice nearby..

Ed wrote:
Tel, what temperature does mead need to ferment?

depends on how fast you want it to go and what flavor you're after.  fermentation should proceed at any temperature above freezing, though very slowly at the lower temps.  things pick up quite a bit around 65 to 70 Fahrenheit.  warmer than maybe 90 Fahrenheit, I'm not sure the fermentation would speed up, and at some point warmer than that, the yeast start having trouble.  toward the upper end, faster fermentation generally requires longer aging to mellow out some strong flavors from esters &c, which can be desirable or not.  low temps usually make cleaner flavors that need less aging, which can be desirable or not.  and I believe that yeast can tolerate more alcohol at lower temperatures, though it would take longer to get to that point.

if the yeast really get going, a ferment can also generate a substantial amount of heat.  a carboy isn't going to heat a greenhouse, but it might speed up some warm-germinating seeds placed right next to it.

Tel, as far as I know yes, we're talking volume. I received a grant to work with university researchers on the respiration rates of cut produce, and we were discussing this in microlitres, but just talked in percentages because it was easier.

Your math sounds right. So, let's say you have some great sustainable way to produce 1 cubic foot of pure CO2. To supplement to the 800 ppm as a commercial tomato grower would do, your 1 cubic foot CO2 would for one instant bring 1,250 cubic feet of growing space up to this level. (1 / 800ppm) With a 10 foot ceiling, you just supplemented for one instant 125 sq feet of growing space. Then the plants start using it up, and you're out of CO2, and the effect continues to diminish, until you are down below atmospheric levels, and you'd be better off venting. The point is that you need to maintain the 800ppm for the duration of the growing day. That takes a lot of CO2.

But anyway, my interest in continuing this discussion is waning, so let me just say ya'll have fun experimenting and designing and if you have good hard data to report, I'd love to read it. A cheap gas analyzer runs about $4,000 US and measures O2, CO2, and water vapor. For a little more money, it would also measure CO.

NM Grower wrote:
But anyway, my interest in continuing this discussion is waning

for what it's worth, I've appreciated your reasonable and experienced voice tempering my wacky ideas.

NM Grower wrote:
Your math sounds right. So, let's say you have some great sustainable way to produce 1 cubic foot of pure CO2. To supplement to the 800 ppm as a commercial tomato grower would do, your 1 cubic foot CO2 would for one instant bring 1,250 cubic feet of growing space up to this level. (1 / 800ppm) With a 10 foot ceiling, you just supplemented for one instant 125 sq feet of growing space. Then the plants start using it up, and you're out of CO2, and the effect continues to diminish, until you are down below atmospheric levels, and you'd be better off venting. The point is that you need to maintain the 800ppm for the duration of the growing day. That takes a lot of CO2.

I figured as much.  it's not easy to figure just how much CO[sub]2[/sub] a greenhouse full of plants will use.  my general feeling is that if I'm going to be doing these things that produce carbon dioxide anyway (and I am), and if I've got some room in the greenhouse, then it makes sense to produce that carbon dioxide in the greenhouse.  results might be small, but so are the resources used.  doesn't matter that there most likely won't be a vast improvement because it's easy.

if somebody is composting anyway, then it makes sense to do that in a greenhouse like you mentioned, supposing that it doesn't take too much space or effort.  if somebody spends a lot of time doing push-ups or running on a treadmill, I might suggest doing those things in a greenhouse.  takes a little space away from growing, but not a lot.  maybe a combination greenhouse/gym will be showing up in a liberal suburb near you soon.  probably not.

Oh yeah, I can definitely get behind stacking all the CO2-producing functions into an integrated greenhouse. A gas cookstove, a treadmill, the compost heap, fermenting mead, chicken breath (but not their manure due to the ammonia), choir practice. Can't hurt, might help a wee bit, and sure feels like permaculture.

This guy has some really good ideas, including for greenhouses

http://www.themodernhomestead.us/article/Greenhouse.html



This is a most effective use of space in the greenhouse.  19 plants on one 5 gallon bucket, by making holes in the sides.
Get 55 gallon drums and the possibilities are startling.

http://www.youtube.com/watch?v=MjY3C81zSZM&feature=fvwrel


More ideas:

-  Build the beds with some hugelculture aspects, burying wood in them, for starters.  This will cut own on watering and increase the microclimate biology.


If you want to get off the ground for ease of working the soil, try this.
--- build a 3 foot platform box for the soil, and put it on five gallon buckets ful of water.  The water will modulate the temperature alot, a heat sink and coolth sink also.

The question  I have about 55 gallon drums etc is what do they use for soil and how do they maintain fertility?  A 55 gallon drum will swallow a LOT of growing medium, even a 5 gallon bucket will take quite a bit more than a person might expect.

I saw one video that the guy had water in the bottom half of the drum and just planted the top half (how he made the separation I don't know.) This made the one barrel a heat sink as well as garden and cut in half the amount of growing medium needed; but of course also cut in half the plants that could be grown.

Another question is light; this system would need lights? As otherwise the plants on the back and sides of the barrel would suffer from lack of light? Or else a person would have to rotate them every other day or so?  Can't imagine doing THAT with a 55 gallon drum unless it was set up on casters.

The main thing though is the growing medium.

As far as the second link which includes videos of growing things in holes in pipes; hydroponic gardeners have been doing that for years. There is information galore in libraries  as to how to set up those systems (or variations of them), everything from growing lettuce in a dishpan to full scale commercial enterprises.

Watering in any sort of raised bed seems to bring its own set of problems. What looks to me right now as the best solution  are wicking beds that were developed in Australia. These could and have been incorporated into grow barrels as well as "normal" raised beds.

Hi Pam.

"The question  I have about 55 gallon drums etc is what do they use for soil and how do they maintain fertility?"

Yes, everything is multiplied with this system.  You can grow 10+x the produce on the same space of dirt.  So how to keep the soil vitality up? 
Basalt, rock powders. 
Kelp
Soft rock phosphate, or hard rock (not as good).

The wood buried within the soil should help it keep alive.

Bury charcoal.

There are yahoo groups who are really into maintaining the vitality of the soil, ala Albrecht.
"Soil and Health" with Steve Solomon is a great group.  And there is a Brix yahoo group which is invaluable for those who are serious about going the extra mile for nourishing produce. Basically, with a Brix measuring device one can tell how much minerals and sugars and other elements are in the food.

LIGHTS

Yes, one side tends to be more shaded.  The guy who markets the videos on this says you can put reflective material on the ground on the dark side.
Perhaps the dark side could have less holes on it.
It could have more or most of the charcoal and wood on that side.
Many plants would probably do fine with mostly indirect lighting.

They have all kinds of remarkable stories such as this.  The originator of this Brix knowledge grew a melon and won a prize in the county fair.  Now since high Brix produce won't age or rot [yes, amazingly so] he entered the same melon in the fair for the next two years!


WICKING GARDEN
Thanks alot for the info on the wicking garden system.  That is what my intuition was leading me toward, and I am grateful someone has worked out the kinks.
Here is a site with links on this 

http://green-change.com/2009/05/01/wicking-beds-water-efficient-gardening/


The tarps at billboardtarps.com would be very helpful and low cost for this.