I have a notched Brushy Mountain inner cover that I invert in the winter for a top entrance/exit. On top of it, I have a 1 1/2" piece of Styrofoam (with center hole coinciding with center hole of inner cover) to keep in the warmth and allow condensation to escape. I have a 4" vented feeding super all year round to allow for this. (I recall many posts discussing vapor escape and convection currents). Yes, the "windows" may be open on top but I don't have it raining on the bees in the winter nor a mold situation. Seems to work for me.