The material is well-made and designed to last so either storage method will work just fine. That said, make sure that the material is dry before packing it away so that the material won’t be imprinted and waterborne sediment won’t build up and soil the screen. Storing the material at an optimal room temperature will ensure that the screen will be suitably pliable enough to stretch onto the framework without much effort. Storing the screen in a cool place won’t hurt the material but it does make the material a little tougher to stretch over the frame when assembling.