Erm, how do you clean the outside of the glass? If you're high enough to benefit from putting a balcony in then this design prevents you from cleaning the outsi

Erm, how do you clean the outside of the glass? If you're high enough to benefit from putting a balcony in then this design prevents you from cleaning the outside. I know that Pilkington made some hydrophobic layer for one of their products a while ago that meant that the rain would clean the window (or a hose), but that was years ago and doesn't seem to have found favour (I've not heard of it since).