I've been growing orchids for years in the pool cage and the temps are the same inside and out. All I am after is the same inside and out with the addition of good air movement. With the screen I had some reduction in the sun and with the polycarbonate I have the same plus no UV rays. I just don't want heat buildup under the roof and I should be able to clear that out with a good exhaust fan. Most of my orchids are warm growers and it gets hot in their native habitat as well.
Jim
