N1102.3.1

Section N1102.3.1 is titled 'U-factor' and covers requirements for energy efficiency. The allowance for an area-weighted average of U-factor for fenestration is established. The purpose of this section is to allow for a 'trade-off' of lesser and greater U-factor ratings than required by the prescriptive table in this code which achieves an overall equivalent energy efficiency for the building.

The model shows a wall with two windows which change in thickness to symbolically represent an area-weighted average U-factor of the windows. (The thickness of a window frame, in and of itself, does not necessarily correlate to U-factor ratings).