location for greenhouse in Texas

I have ordered a greenhouse and I am now trying to determine the best location for it. I live in Austin, TX where we get a few months in the 100 degree mark. I live on a heavily wooded lot that has a lot of cedar on it so the only locations that get measurable amounts of sun in the winter are west facing. I will use the greenhouse only during the winter months. I am trying to determine if I should place the greenhouse under deciduous red oaks to try and create some sort of wind block for it and some shade for the structure in the summer months. I am concerned about the oaks falling on the greenhouse as every year I usually lose a few and ,my luck, it would be the ones right over the greenhouse. Is there any real harm in having it west facing, out in the open? Thanks so much.

What size is the GH?

If it's out in the open and more exposed to wind, that could be a concern depending on what sort of greenhouse it is, if you live in a really windy area some GH's might not stand up very well to that. I'm also assuming in your zone you have a decent number of days even in the winter that are sunny and warm during the day? If so then you'll need to plan for ventilation even in the winter. If I didn't open my GH doors in the morning on a sunny day with outside temps of 55-60, it would get over 100 degrees in the GH while the sun was on it.

As far as ventilation goes, this is a Rion 8X16 greenhouse. They advertise that the roof vents open automatically when it gets warm. Anybody know how well these work?

Does it also come with a fan to help circulate the air? If not, I don't think just having the roof vents open will be enough, especially as you get closer to spring and your nights are still cold enough that you don't want to take the plants out of the GH but the days are getting warmer.

No, there isn't a fan. Today I have been trying to research heaters and evaporative coolers. I have looked but I don't seem to find anyone listing which types work best for them. Would a forced air heater be the best thing for a GH?

I don't know that there's one type that's better than another. First you have to decide gas or propane vs electric. I don't know that either one is really inherently better than the other, but depending on electricity costs vs gas or propane prices in your area you may find one is better for you. Electric powered ones of course you need an outlet nearby and if your power goes out a lot, so will your heat, so that's something to consider. Once you decide that, then it's just a matter of finding something in your price range that will be able to provide enough heat for a greenhouse your size. Stressbaby's got a lot of good info in some previous threads about heating greenhouses, so looking through the old threads might be a good place to start. When you're ready to shop, www.charleysgreenhouse.com has a good selection of heaters in a variety of price ranges. Here's the one that I have, it has no trouble at all keeping my 5x9 greenhouse at ~60 degrees. http://www.charleysgreenhouse.com/index.cfm?page=_productdetails&productid=4045&cid1=201&cid2=264&cid3=-99 I'm not sure if it would be enough to heat your greenhouse since it's much bigger and your climate's a little colder, but you could check with some of stressbaby's calculations and see.

If you're not planning to use it in the summertime, I think the evap cooler would be overkill, just get yourself a good fan to move air around when the vents are open on warm winter days and you should be OK.