a building cleaning system for cleaning a side of a building can include an elongate brush structure that is rotated by an electric motor , a frame for supporting the brush structure that can be oriented to face toward the side of the building , and a plurality of air moving devices mounted to the frame for generating counterforce to force the frame toward the building . the air moving devices can including fans or blowers . the air moving devices can be being spaced apart from one another in an orientation that extends along the length of the frame . a lift arrangement can be provided for moving the frame along the side of the building .