Hey, ya missed a golden opportunity; ya should've suggested adding a "passive solar heating enclosure" to the side of your house!!!
Perfectly see through, of course, using a thin mylar membrane that would not need replacing every year from UV degradation like plain old plastic sheeting.
It would add an excellent buffer zone, protecting that part of the house from "direct contact" with outside weather.
That's assuming a south facing wall, of course.
It'd otherwise be of lesser effect but still an excellent windbreak!!!
(not to mention you could open the windows to let the extra heat in during sunny days.)
It might not be too late if ya haven't chopped up the plastic too badly yet...
Using PVC pipe would've given a stiffer frame, even if it's more work to get to bend as nicely as possible. A heat gun or careful application of a flame does the trick though. Worst case scenario would have been adding some elbows, not overly expensive.
Please consider going with a double-skin on the critter; the slight extra effort and expense will be more than offset by not just lower heating costs but by final success.
If you need more height, a row of straw bales around the bottom will not only add height but also an insulated "buffer zone" from cold extending through the soil.
I know the "up against the house" part may be a bit of a hard sell for you at this point but have a look-see at a very easy, inexpensive, and effective little "passive solar heating enclosure" that your folks will wind up loving when the heating bills roll in:
Banana Gallery - lean-to
It can be made with straight pieces & elbows but the arch gives tremendous stability in wind gusts up to 40 - 50 mph.
We used plain old heavy polyethylene plastic sheeting but polyester (Mylar) is crystal clear because of the view being an issue.
Here is a place selling Mylar film so you get an idea of what you would be dealing with:
Clear Polyester MylarŪ | U.S. Plastic Corp.