simply trad ground floors and avoid wfpoling windows directly above a door unless you sweep water away and salt it.you ll find you hardly leave any water on the ground if just poling tops anyway.
im lucky as a lot of top windows on my round this coming week are on one estate where there is a sloping roof below them stopping the water hitting the ground.
the only problem i can see is if the water starts freezing on the glass or in the jets of the brush.if it does then ill probably go home and call it a day.
dazmond