As of Season 3, Ellen's apartment is no longer upstairs: the characters go into the first floor apartment opposite Mrs. Koeger's. An establishing shot regularly shows that Ellen's apartment building is not exactly at ground level, since there are stairs leading to its entrance, from the sidewalk. However, its first floor isn't high up enough to be at the same level with the top floor of the opposite building which is seen on level from Ellen's balcony. Also, a couple of bushes clearly obstruct the view from the downstairs apartment's windows but Ellen has unobstructed view ahead, proving once and for all that Ellen's apartment is clearly the one upstairs--even throughout season 3. Furthermore, the top floor window is lit at night in the establishing shots, proving that it is Ellen's. Finally, the "balcony" seen in said frames appears to not be a balcony at all once seen from the outside view: there isn't nearly enough floor space. The balustrade appears to be smack against the window, with only a slim space to host potted plants, but evidently not large enough to accommodate Ellen's patio furniture.
