a trick for doing things like this, if you're not aware of it is using the selection criteria tool, and the edit selection set tool (the soviet button) assuming all the clerestory windows have at least one feature the seperates them from the rest of the windows in the building, you can use the selection criteria button to quickly select all the clerestory windows. Go to edit->find & select. then chose window and under that choose (as an example) sill height, then greater than, 3 metres. then hit the '+' button at the bottom, this should select all the clerestory windows, and nothing else (assuming in this example that all, and only your clerestory windows had a sill height greater than 3 metres) then put them on a different layer using the edit selection set tool (the hammer and sickle looking button next to the layer drop down on the information pane) I'm not sure if you were aware how to do all this, if not, I hope it helps you.
cheers,
daniel
