PVC Greenhouse

I found some online plans for how to build an inexpensive greenhouse.

I am not sure about doing this. I know that in the past when I have researched greenhouses, they actually require a bit more work than just set it up and let it go. There is temperature and air control. We do have a space heater which can be mounted to a wall (even though this greenhouse would have no walls, I wonder if we could build a small wooden one in there?). I think it definitely requires more looking into.

Has anyone built this type of green house (or ANY type of green house?). Any words of wisdom you can share??