too hot in the greenhouse

We finally finished our Rion 8X16! Yea!! Put the thermometer/hygrometer in it yesterday afternoon and checked it today and the max was 108! Gees, in February!! It was 75 degrees here yesterday, and that is nothing for Texas. All of the louvres and ventilating roof vents were open. I see on the Rion site that you can buy additional louvres.Should we buy more and, if so, how many? Has anyone every installed a fan in one of these to suck out the hot air? Opening the doors will be difficult as we have deer that would love to go inside. I could probably drag a baby gate across the door or something; hopefully they wouldn't want to jump in? Any suggestions?
Annie

You seriously need a fan to suck out the hot air. Close the roof vents and just have the fan and shutters. If you can put the fan on a thermostat, it will make your life a heck of a lot easier! Also keep the door closed when the fan is on as well and you will get better air circulation/pull thru the grhouse.

I agree, you definitely need a fan. Putting in more louvres won't really help unless you have a fan to circulate the air.

Passive ventilation will generally keep you only within about 20-30 degrees of the outside temp. Exhaust fan is (part) of the answer, it will get you to withing about 10 degrees of outside temp. For more, you need evap cooling and/or shade.

I have an 10 x 12 with 3 windows and a large door. It was 110 in there today with everything open. It was 82 outside. I don't have any plants in it yet, because I need to get shade cloth. I'm wondering what percent shadecloth I should get for Florida, cause it gets in the 90's here.

I will be reading everyone's reply with what you should do with yours.
Mine looks like this.

~Lucy

That is a good question about the shade cloth. I purchased the one that Rion sells to go with it thinking that I would be using it in the summer just to protect the GH. I don't have any plans to have plants in it during the summer. But, how will seedlings, vegetables and tropicals get enough sun with a shade cloth? Do you then have to go to grow lights?
Annie

If you get a fan going in there then you might not need the shade cloth during the winter. The fan is really going to help a lot with your temperatures

I think that you will need the fan. In the summer I use 50% Aluminet, exhaust fan adequate to exchange the air every minute, plus some mist/fog to keep the temps right at or maybe just below outside temp.

The plants will grow fine with the shade cloth, even sun lovers. Citrus, for example, can only use about 1/3 of the PAR that they get in full sun. So a 50% shade cloth still keeps them in maximally effective solar radiation.

Thanks stressbaby, very useful information. : )
~Lucy

SB, you are talking about using the shadecloth in the summer-not the winter, right? I really think that the winter sun is not strong enough to give full sun plants enough light in the winter. I think the plants will start to get leggy with a shadecloth in the winter. In fact, I find that my pansy seedlings under shadecloth in July/August start to get leggy. As soon as I can, I remove the shadecloth. I guess it depends on what you are growing.

I think it also depends on where you're located. I still have 40% Aluminet shadecloth on my roof and south wall, in early February, and I'm frankly wishing I'd had the foresight to order 50% like Stressbaby did. Here in NM we have a large number of clear sunny days, and I'm at an altitude of about 4000 feet. At least, I think altitude has some bearing...my understanding is that UV intensity increases with altitude because of the reduced distance the radiation has to travel through the atmosphere...so it has less chance to be diffused or scattered before it gets to my greenhouse.

In any event, it's becoming clear to me that my shadecloth will need to remain in place year round...even though I grow succulents, most of which are full-sun plants. So, I think it must vary from location to location.
Sheri

I guess it depends on where you are. It's supposely winter here in FL, and I need shadecloth, bad. It's down right hot as heck, in that greenhouse. I am getting plenty of light. : )

So, you all like the Aluminet shadecloth, the best? Anyone have any pictures?

It's the only shadecloth I've tried, so I can't compare, but I do like it. It's very lightweight, but surprisingly strong. It doesn't unravel if you cut it. Here's a website page that has some pics at the bottom, and explains more about it. This is also the website I ordered mine from:
http://www.igcusa.com/greenhouse-shade-cloth-aluminet.html

You can order it hemmed, with grommets, or raw. I ordered mine as raw fabric since I wanted to use it to make screens, and to custom made a shade for the inside of my roof...I wanted to play with it!

I didn't drape it over the outside of my GH as many do, because I felt like it would be hard to keep in place in our awful winds. I put it inside the roof. People say this is less efficient at reflecting heat when you use it inside, but I thought I'd try it inside first (easier for me.)

Thanks olemud. I'll check that site out. : )
~Lucy

Also wanted to say, AnnieJo, I don't have a Rion greenhouse...but if I had not installed an exhaust fan in my Harbor Freight (I have the 10x12) my greenhouse would be totally unusable in summer.

After we finished building the greenhouse in August, with the double doors and four roof vents open, it got to 140° in there. Holy cow! We installed an exhaust fan, shadecloth and screens before I moved my plants in. So, I totally agree with the other posts...an exhaust fan and louver vents will make a huge difference. Cooling is my biggest challenge...and I'm still learning!

Ole Mud...did you run you shadecloth down the sides alittle, or just on the top? I'm getting alot of sun on my south side.

I did something kind of odd on the south wall, because of the way my greenhouse is made. My GH poly panels are easily removed, so I took out some panels and replaced them with screens I made from the Aluminet shadecloth. I bought the do-it-yourself window screen supplies from Home Depot, made the frames, and stretched the Aluminet in them. That gives me open air on most of my south side, and the benefit of some shade at the same time. It does allow rain in on that side, but our summers are so hot and dry it shouldn't be much of a problem.

Right now, in the winter, I have my poly panels back in place (cold nights!) but I still have the Aluminet screens in place on top of the poly panels to give me the shade I need on that hot south side.

If I hadn't been able to make the shadecloth screens, I would definitely still have needed to apply shadecloth to my south wall some way, inside or out. I think lots of folks apply the shadecloth over the roof and down the south wall, all the way to the ground, or close.

That looks really good. Smart thinking on the shadehouse screens. I'll probably end up shading my whole south side, cause I don't think my sides would come off and on, that easy.
The prices at that site you gave me weren't bad, for the regular shadecloth. I wonder tho, how much more the Aluminet would be. I'll probably have to call them, after I get some measurements.

Thanks for giving me some good ideas. : )
~Lucy

Here's their page for the 50% Aluminet (I think the page I gave you the link for didn't have easy ways to get back to the main website, sorry.)
http://www.greenhousemegastore.com/prodinfo.asp?number=SC%2DAL50
The drop down arrow will give you a list of prices. It does cost more than regular shadecloth...I was just so focused on my heat problem that I decided it was worth the cost. And, buying it raw saved me some money.

I also made a big triangle-shaped piece to go on the west gable end of my GH, over the doors, to block out some late afternoon sun. It's just held on with Velcro, on the inside of the GH. I just rolled the edge over a few times and sewed a hem with a big plastic needle and nylon thread. It's kind of odd stuff to work with, but not difficult.

I'm thinking I'll make a shawl for myself next! ;-)
Sheri

Oh, thanks Sheri, that page answered alot of my questions on price. : ) Now, to get DH to help me measure. I guess I will go with 50%.

A shawl? LOL : ) You could make a shadebrella, too. : )
~Lucy

Can I simply use a box fan turned outwards facing for an 8X16 GH? Or do I need to buy one specifically for this?
Annie

I would make sure you buy a fan that's rated for outdoor use, my guess is your box fan is designed for indoors and you should never use indoor electrical items outdoors.

I will need to check. These are fans that we use at the barn that our horses are boarded at and we have an extra one. They are obviously outside in the barn, but I will check and see what they are actually rated for. Thanks!
Annie

I think that you need a 16" fan that you insert into the endwall at the end of the grhouse and then two shutters (maybe 12" wide each), one on either side of the door at the opposite end of the fan, and a thermostat that will turn the fan on when it gets too hot. I really think that that is going to be the easiest, fastest way to cool your grhouse down. If it were shorter than 16' , you might be able to get away with just sticking a fan in there, but with the length of your grhouse, i think you need a stronger fan, and shutters.