site for greenhouse.

My latitude is slightly above 40N and my longitude is around 88W. Is there any site out there where I can plug my latitude and longitude that will spit outw the optimal orientation for my greenhouse?

I know that as a rule of thumb, orientation below 40 should be north/south and that orientation at or above 40 should be east/west. One problem, I'm darn near at the cut off which in my mind means an orientation of NE by SW.

I'm in a colder climate so I need to maximize solar exposure. I do realize the long side needs to be perpendicular to the sun. I've got a lot of space here so I truly would prefer to site this perfectly.

I found this site that was very interesting-
http://www.umass.edu/umext/floriculture/fact_sheets/greenhouse_management/jb_haf.htm
I'll need to determine where to place my fans at some point in time.

IMHO, the 40 latitude rule oversimplifies the factors that go into determining the orientation of a greenhouse.

It is true that E/W orientation maximizes light, by up to 20-25% over a N/S orientation, depending upon it's shape. But if you maximize light, you maximize heat, and generally cooling a greenhouse is as big a job as heating one, particularly a smaller hobby greenhouse. If your only purpose for the GH is to overwinter carnivorous plants at min 40*F, and keep your costs down, then E/W may be the way to go, but...

A greenhouse oriented E/W may have more light but the light may be less even due to gutters, ridges, and other portions of the GH structure which cast continuous E/W shadows. These shadows pass uniformly over all portions of a N/S greenhouse.

Visual aesthetics? Can you see the greenhouse from your house? What part of the greenhouse would you like to see from you kitchen window?

Noise? If the exhaust fan is aimed right at your back porch, you won't be happy.

Landscape design? Where do you want the door in relation to your traffic through the garden?

I don't think the long side automatically needs to be perpendicular to the sun. I'm only 1/2 zone warmer than you are, and my GH is N/S.

Regarding fans, two thoughts. First, I like the umass link as the best discussion of HAF I have seen on the web. But I don't like their HAF cfm calculator. I originally used their formula when I calculated my HAF requirement and their numbers are too low for my needs. Their formulas may be fine for commercial greenhouses, but I think that they underestimate the HAF needs of a hobby greenhouse (I have a guess or two as to why that might be, but that's a different discussion).

Second, you don't need HAF when the exhaust fan is on if your intakes are properly positioned. If I were building again, I would wire the outlets to the HAF fans to the same 120VAC line, run this line to my relay box, and install a relay on that line that will shut off the HAF fans when power comes on to the exhaust fan. 4-5 months a year my exhaust fan runs 12 hours a day or more and you don't need the HAF at that time.

SB

SB, I keep forgetting to mantion this, but everytime I see a picture of your shutter I mean to ask you-is that the only shutter you have to your grhouse? It seems so small and up so high ( which I partly get-hot air rises and its nice not to have that cold air blowing on you in the colder months) . But is that your only one? Doesn't seem like enough. I have 2 shutters on the sides and the small fans running down the center for better air flow. The small ones have to run all day. They run all night too-which is their most important job, imo. Do you run yours at night?

Tigger, he probably has two. And I think your greenhouses are commercial sized too which probably makes a big difference.

SB, Can I see the greenhouse from my house... depends on where I put it and where I am in the house. Will I ever be able to view it from my kitchen window- nope. The design of this house will prohibit that as this is a complex design as opposed to being a classic rectangle.

I am leaning toward a NNE/SSW exposure right about now. Your thoughts on that? Yes, there would be microclimates within the greenhouse but then I can play around with that in the future. The greenhouse is 14 x 25 if memory serves me. From that location, I would be able to see the greenhouse from the north side of my home. There are other locations here that I could choose.

Noise, not a concern. This house has sound batting in most of the walls and although we have a fully screened in porch, we hardly ever use it in favor of sitting on the patio which has atrium doors to the family room and the kitchen where the refrigerator is that has the food. We all like to eat a lot here. The screened in porch is very nice but it's by a den and a bar room and nobody around here drinks liquor. That's why we hang out on the patio. Closer to the food source and we have a decent little patio set with an umbrella which works just fine for us.

I will need to figure out exactly where to put the exhaust fans though but I was thinking one at the back of the greenhouse with the doors on the side facing the house. I don't particularly want to have to walk around the greenhouse to get in it and additionally the winds here are prevailing from the west and north. Are my thoughts ok on this?

We need to start moving plants around now before the excavators come this fall and before the concrete gets poured so I've got to pick a site fast. Maybe I should just send you the survey to this house and as long as you picked out everything for me to order for this greenhouse... you might as well just pick out where to put it too ;)

I do thank you very much for helping me... no scratch that... for choosing everything for my greenhouse. I am thrilled with everything we ordered.

Hi guys,

The higher shutter is the exhaust fan. Low on the opposite end I have two motorized intake louvers. Also, I leave the glass up on the screen door in the summer. So the exhaust fan draws air from three points on the opposite end of the greenhouse. (See pic, w/ Dad since it is Father's Day!)

One person told me when I built that given my GH width, I should have two exhaust fans. By the time they told me that, I had already ordered and planned the whole thing out. Installing another fan is a pain with tempered glass, because you can't cut the glass, you have to special order it. I have one fan, properly sized, and so far, so good (knock wood/head!).

I think your orientation will be fine if it fits with the other factors and site properly.

Which direction is the GH in relation to your home? Prevailing winds from the north? Here, when it does blow from the north it is cooler and the exhaust fan isn't as likely to be on. It is the hot southerly winds that you don't want to fight with your exhaust fan, I would think. I would put the exhaust fan high on the NNE end and intake louvers low on the SSW end, drawing air across the length of the GH. I would increase by a factor of 1.5 or 2 the cfm result you get from the umass HAF formula for your HAF fans. Have you bought fans already?

SB

Happy Father's Day to you and your Dad!

The greenhouse will be to the north and a little bit east of the actual footprint of the home. If we were to sit out in the screened in porch, we'd have a great view of it otherwise we'll have to be in the north side of the house to see it.

Ummm yes, I bought the fans you chose for me in the size you indicated was best for my size greenhouse. I don't recall exactly what size they were but what ever you told me to buy is what I bought.

Prevailing winds from the west or north it seems. The back of the greenhouse is the NNE side so I guess that was a good call for at least one of the exhaust fans. Should I stick the other exhaust fan on the same side or move it to the eastish long side of the greenhouse? Same question for the intake louvers which I had already decided to put at least one on the SSW end of the greenhouse and maybe the other one on the same side or on the westish side? Your call. Whatever is best.

I don't believe cooling will be an issue. The panels of my greenhouse are removable. They look as if they are removable on yours too. Are they? Maybe in the future I will check into a swamp cooler but I don't think there is a need to do so now.

One thing I am not particularly thrilled about is the space the waste oil heater is going to take up. I did order a 30000 BTU gas ProFlame heater as a back up too so I don't know that I am all that thrilled with losing floor space. Oh well.

Ok, got it. I guess the size of the fan threw me off because it is so small. They say to have two shutters, together in size, equaling the size of the fan. Obviously you don't have that kind of setup. Yeah, I know my grhouse is bigger, and often I have a hard time switching "downwards" in sizing needs for a smaller house.
Nice picture SB-happy fathers day!!
I see the door in the pic, but not the louvered shutters-but it looks like the roof opens? If so, do you find that you get as good a pull from the fan with it open?
I'm in a pouty mood...Hurricanes lost again last night, I'm starting to think they are choking-which surprises me. and doesn't make me real happy....Monday pm is the big one now.

Tigger, I must be out of the weather loop! What's going on down by you? Maybe you should fly up by me... for protection you know from all those nasty weather systems you have pushing through your area. We could hit both Jamaican Gardens and we could get a good run down to Hauserman's Orchids. Then when the threat of the hurricanes is gone... you can fly home with goodies.

lol you are the silliest goose I know!! I know you don't like sports.....but this is too much!! The Hurricanes-the hockey team-the chokers-you know...

Stop talking about that tropical nursery or I am going to be on a plane. I have a few empty spots in the new gardens that I am planting- boy you sure know my weak spots lol that could be bad. If I bought a 6' high palm would I have to purchase an extra seat on the plane on the way back? Andy Roddick did for his tennis trophys, my palms are just as important.
If I come, will you sign us up for a weaving class??? VV needs a pair of lapti lapti shoes....
Why don't you share with SB all about the medicinal properties of my river birch, and while you are at it, ask him about that fungus on your legs since we haven't learned how to weave yet??? lol

Stop threatening and just get on the plane and go shopping with me! Lord knows we have enough extra bedrooms here.

Hurricanes are a sports team? What are they doing at your house? Trying to protect you from the big bad roots of that horrible tree by your slab foundation? I suppose it's ok that they're there as long as one of them holds an umbrella over your head while another drops grapes in your mouth while you collect all that nice sap from a prone position laying in your bed with a gaping hole over your head from where the tree crashed through.

Fungus on legs? Weaving class? I step out and you guys get totally goofy on me. And I knew which Hurricanes you were talking about. I'm not watching, tho, since the Redwings are out.

My intakes are deliberately over sized for my greenhouse. The ridge vent does not appreciably change the exhaust ventilation.

How many exhaust fans do you have? I don't remember what we talked about before. What size? Sorry to sound spacy...

OK, your GH is NNE of your house and oriented NNE/SSW. Your fans are far more effective if pulling the length of the GH rather than the width. Assuming that the door is on the end toward the house, you can put your fans widely spaced on either side of the door with the intakes in the back, or you can put the intakes widely spaced on either side of the door and the exhaust fans in back.

I know you say your winds are from the north and west. But I think if it were me, I'd put the fans on the north side. Two reasons... one, as I said, winds from the north will be cooler and from the south they will be warmer and obviously the exhaust function is more important when it's warmer; second, those fans are loud, and the sound carries. Believe me when I say you won't want to hear it when you are working outside in the yard.

TL, what do you think about this arrangement?

If you guys do go tropical shopping, pick me up something coolio. ;-)

You could do something like this, I suppose.

On a greenhouse this small, why would you have two fans? I am pretty sure that one fan will do the trick nicely. I would have two shutters. I am not an engineer of any sort, but I have never seen a fan on the side of a grhouse-it seems very inefficient for pulling air down the grhouse.

Here is how every grhouse that i have ever seen does it-
on one end (gable) you have a door in the center and a shutter on either side-upwards of 2/3's high from the floor. At the opposite end you have the fan-roughly starting at about half the distance from the floor and the top of the fan will bring you about 2/3' up from the floor. The two shutters equal the sq footage of the fan. They draw the air down the sides of the grhouse. In the center of the greenhouse 1/3 of the way down you have the first small circ. fan and 2/3 down you have another small fan. Then the air throughout the grhouse is circulated outside the quickest way. Why change this tried and true method?

The way SB has drawn it-at the end where the two fans are-there is going to be a huge amt of air that is going to go across your aisle and the growing conditions at that end are not going to be favorable-for you or the plants. They will be short and stumpy because of the air flow. Same at the other end with the intake shutters. This is a bad, bad, bad way to do this. SB-stop listening to her rambling thoughts on where to put the fans/shutters. She just wants to be told where to do it, and maybe why-thats all, stop trying to please her-its our grhouse-not hers lol


Equil--are you saying I should start checking the airlines out??? What about the dogs, the new tropical garden-the 18 yr old who would so fast have a party lined up the day I left ( he doesn't fall far from the tree!!)

OK TL, you're right...I thought she said two fans...

TL's description is almost exactly the way my greenhouse is built. But my shutters are 24" and the fan is 22"...intake shutters on both sides of the door, exhaust fan high on opposite side. This is what I proposed in the 12:44 post, but if you have two fans, just space them apart on the back wall. With just one fan it would look like this.

With two fans it would look like this:

Now are we on the same page, TL?

Your last design works for me. I have two intake shutters and two exhaust fans.

Cool, post back when ready to talk about wiring/electrical...

Robert

Yeah, but...

How many greenhouses has your electrician wired? He's just gonna do what you tell him to do, so you want to instruct him to do it right the first time.

You can't bring the guy over and say, "Wire my greenhouse." It all depends on controllers, thermostats, fan placement, blah, blah, blah... that's all I mean.

Good question. I have no idea how may he has done. After we get the structure up, we can figure out what to tell him to do. Right now, the priority was to pick a site and I think I have done that. Now that site needs to be cleared of some brush, a Green Ash needs to be removed, and a DED resistant Elm needs to be relocated. I've got a really full plate for the next few months and this is going to have to be done before the excavators come. I feel a lot better about the site I am going to go with. Now, all I need to do is get the preliminary clearing behind me to make way for the foundation. Everything else will fall into place sooner or later.