We usually use exterior screens to block sun or insects. In this case, our customer wanted to use tight screens to significantly restrict air flow, allowing the heaters under the porch to function better. MotionScreens from Universal Screens can withstand moderate winds when used with the zipper tracks enclosing all sides of a porch. The Suntex 97 fabric from Phifer blocks a pretty significant amount of air flow. Somfy motors power the shades, making operation simple. And the new Carbon fabric color is pretty sweet!