The glazing factor calculation is based in part on the window area of the space. In our project, the window head height is right at the ceiling, and the ceiling steps down about half way back into the space. Is it acceptable to use the actual window area in the calculation, or should the area be adjusted based on an "effective" window height? Can this effective height be the average ceiling height for the space? In other words, if the window head height is 10\' and the average ceiling height is 9\'-6", should 9\'-6" be used as the window height when calculating the window area? In summary, the area is roughly 94\'-0" wide by 10\'-4" with a ceiling height of 11\'-6" before it drops down to a 9\'-6" ceiling that is 19\'-6" deep.
No, it is not acceptable to use the actual window area in the calculation in situations where the ceiling height drops down lower than the window height. The calculator used to show compliance under Option 1 is not set-up to take into account these kinds of geometries. In these kinds of situations, the effective window height must be used, i.e. the height of the lowered ceiling plane. Alternatively, the project team can elect to follow the compliance paths under Option 2 or 3 both of which are better suited to take into account the design situation described in this CIR request. Applicable Internationally.