There's no plan elevation view in Sweet Home 3D.
But you can simulate it more or less in the 3D view: in Virtual visitor mode, select the location and angles of the camera to view the side of your home from far away with a small field of view (< 10°). To get more accurate results, use the dialog displayed by 3D view > Modify virtual visitor menu item.
Not completely sure the scale of each level can be exact with this method.