take a look at http://solaroof.org/

I hopefuly will be setting up my new greenhouse using at least the bubble tech. part of this. They claim to be reducing heating costs by 86% in a greenhouse they have operating in Ontario. While i can't vouch for everything on the site, the basic concept seems sound. They also have a yahoo group where you can ask questions.

Good luck!
Poppa

It can be done, for about a $15,000 up-front cost and a couple hundred per month in winter in heating-more if you supplement lighting w/artificial light.

Hairmetal, please be more specific. What in the world is the $15K up-front cost? Structure? ?? Thanks!

I am venting a bit-I was pricing what I'd like online and figured that's what I'm looking at out the door for structure, glass, heating, wiring, paying to run a gas line 122 feet back from the house...etc.

I feel your pain believe me. I'm looking at a structure around the 20W x 28L and my finger is poised above the speed dial for 911. It won't do me any good to get a structure within my budget and find that my heating bills are several hundred a month. I feel like going home and having a plant bonfire. They will go up in smoke like my dreams.

Jay,
I live in central Ohio and I have a 20' X 25'hoop house covered in 2 layers of woven heavy plastic (with a fan blowing air between the layers). Also put bubble wrap (the old solar cover from the pool)5 feet up the north side and 2 feet above the foundation on the south side. End walls are 1 inch thick plywood. I have 2 30,000 btu propane heaters, one on each end wall. This is the 3rd year I've had the house here. I'm finding that I use about 3-500 gallon tanks full of propane throughout the winter season. The first year, it cost about 1500$ for gas. Last year, about 1800$. I used the heaters from mid October until about mid May. I don't think I can afford to use it this winter. I'll bring what I can indoors and let frost take the rest. Linda

Those figures suck...plain and simple. I understand completely that you would not want to continue winter operations. Things aren't panning out well at all concerning this.

They do suck, but the plastic covering isn't exactly that efficient.

I'm thinking the extra initial layout for real glass (double-layer insulated safety glass) is well worth the long-term benefits-better lighting, better durability, better insulation. Although it will cost 55% more up-front and be more prone to breaking.

My concern would be if the neighbor kid hit a baseball through a pane of glass some sunny, cool March day and that night, as temps dip to the teens, the whole thing is lost. Double-paned would ease that problem as it's less likely BOTH panes would break through giving me time to fix it even if during that time I'd lose more heat I could probably keep it at least above freezing long enough to fix it.

Hairmetal...That's what I was thinking too concerning the plastic. However, I still can't get anyone to give me some figures for the kind of structures you and I are obviously wanting to build. I believe I can receive a really good deal but until I can nail this heating issue down, no way am I going to commit.

On the subject of glass... I believe the tempered glass today is pretty tough. The double pane even more so. I'll have no problems with kids playing ball where I'm at. Although the radio controlled planes could pose a threat! May need to rethink the airfield idea. Everything I read about glass on Florian's website really sways me to that end. But going from just the plain insulated double pane(R value of 2.3) to their low E(R value of 4.0) is one heck of a jump in price.

The other mfg I am looking into was giving me quotes for both polycarb and double glass. The double glass was nearly double the twinwall poly. Triplewall was still cheaper than double glass. Hated the looks though.

We can get the surface square feet, the required btu's. What I need is a way to intelligently calculate some heating costs for natural gas usage. Asking too much?

Call your gas company and ask them. That's your best bet. The BTU's used for a specific heater are BTU's per hour. Someone can fill in the rest of the formula.

Low E also reduces solar heat gain in winter so I am almost thinking it would backfire in a way.

You would think so but the way that Florian describes the process, makes it look as though it helps trap heat in as well. It's all confusing for sure. As for the gas co., I contacted them yesterday and so far everyone is scratching their rears like no one has asked this question before!

Can't help you w/gas company.

All I know is that if you're indoors and the sun is coming through a window, you normally feel the sun's heat but with low e windows, you don't-it's like standing in fluorescent light. At least it seems that way.

Perhaps low E on the north roof slope and the north side of the house would help some with regular glass on the rest of it.

Okay. I'm with you now. Makes sense. I couldn't afford the low-e anyway!!

I can't really afford the glass either. Looks like an equity loan might be necessary for all this...

Hello,

I don't know if these figures will be helpful or not, but here they are...

I have a 20 x 23 single pane tempered glass GH, heated with propane and two Empire 24,000BTU heaters to min temp of 50F at night, 60F day last winter. It is on the same tank as the house, so I cannot separate out the two, but the propane bill was about $1500 higher than the previous year without the GH. We got our propane at about $1.10/gal.

Let me know if you want other details.

I'll be doing some things differently this winter.

Jay,

I found the following, which may help.

Q = A*deltaT/R

Q (hourly rate of heat loss in BTU)= A (area of the structure in sq ft)*deltaT (temp diference between inside and outside)/R

This looks to be a variation of the many GH BTU calculators out there. It permits a calculation of BTU expenditure which can be translated into dollars depending on the particular fuel used. Propane is 85,000 BTU/gal. If I calculate my GH to use 26 million BTU in January, then the cost of heatiing in January is 26,000,000/85,000 = 303 gal of propane. At $1.10/gal (last year's price) my cost in Jan is $333.

SB

I need advice from you experienced gardeners. We are almost finished building an 8'x12' attached glass greenhouse. I'm mainly interested in growing all kinds of salad greens through the winter. The greenhouse is built on an 18" existing foundation, so I'm thinking of having a 2' wide raised bed around three sides that comes up to where the glass starts and this is where I would grow the greens. My knees are giving me problems, so I thought that height would be easier than having the planting beds low on the floor.

Then in about February, we will add one or two levels of wire shelves above the raised beds to start seedlings. On the back wall, I would love to grow sweet peas (flowers, not veggies) on a trellis. Has anybody grown these successfully in a greenhouse? I also want to try starting some tomatoes and cukes now to keep as long as possible into the winter. There's a heat run coming from the house, so I'm hoping I can create a little microclimate along that side of the back wall for those warmer season veggies.

So does this sound like a good plan, or are there major flaws in my reasoning? I've done a lot of reading about greenhouses, but I'd love to hear about some real life experiences. Thanks!

MJ

Sorry!!! I thought I was posting the message above as a new subject. Is there any way to switch it?

MJ

"I am very concerned with the heating costs! I need to have an idea of what I am setting myself up for. It won't do me any good to build a nice, big greenhouse and then cannot afford to heat it. "

It depends on where you live, but if you seriously want to have a GH run all year round, a Pit greenhouse is the only economical route.

The bubble-tech is pretty good too. If I had my own backhoe, (which I don't) I'd be seriously thinking about digging in and building a pit greenhouse out back.

Designed into a south-facing hillside, a Pit greenhouse can cut heating costs remarkably. Especially if you add in a bubble-tech roof.

I am in SE Michigan and had a Florian 11x18 greenhouse built on my city lot last fall. I have double pane glass, with low E in the roof sections. It is heated by two Southern Burner heaters, using Natural Gas. I grow orchids in it.

I am really happy with the performance of my greenhouse! I think the low E and shade cloth helped keep my greenhouse cool this summer.

Last winter, the greenhouse was kept at a minimum of 62 degrees. The worst heating bill was around $100 more than our usual bill. My husband was pleased that the Florian was so efficient.

The only problem in all this is that the greenhouse was $$$$. I had no choice, since I am in the historical district of my city, and it is about 10 feet from my neighbors side door. :-/

I myself have considered such a thing but I would rather use geothermal and solar and wind instead of natural gas, try to be conservative and have no greenhouse gasses or anything to harm the environment. I would like to do my part on cutting global warming along with creating food on a yearly basis. I am against fertilizers at the same time, plants on steroids is not good. Plus I want to reuse water instead of sending it to the oceans. Plus have energy efficient vehicles since I am creating my on electric and might be able to sell back, but at least the operation would be econmical and environmentaly friendly as much as possible. The planters would be bio-degradable instead of plastic. Cut out as much oil as possible and try not to have any oil consumption at all.

My thoughts and dreams as I can not afford it but maybe this can be of good use for someone who is wealthier than me.

Thank you.