808.3.1 Daylight Prescriptive Requirements

Daylit areas shall comply with Section 808.3.1.1 or 808.3.1.2. For determining the total daylit area, any overlapping daylit areas shall be counted only once.

The daylit area shall be illuminated by fenestration that complies with Table 808.3.1.1 and Figure 808.3.1.1(4). Where fenestration is located in a wall, the daylit area shall extend laterally to the nearest 56-inch-high (1422 mm) partition, or up to 1.0 times the height from the floor to the top of fenestration facing within 45 degrees (0.785 rad) of east or west or up to 1.5 times the height from the floor to the top of all other fenestration, whichever is less, and longitudinally from the edge of the fenestration to the nearest 56-inch-high (1422 mm) partition, or up to 2 feet (610 mm), whichever is less, as indicated in Figure 808.3.1.1(1). Where fenestration is located in a rooftop monitor, the daylit area shall extend laterally to the nearest 56-inch-high (1422 mm) partition, or up to 1.0 times the height from the floor to the bottom of the fenestration, whichever is less, and longitudinally from the edge of the fenestration to the nearest 56-inch-high (1422 mm) partition, or up to 0.25 times the height from the floor to the bottom of the fenestration, whichever is less, as indicated in Figures 808.3.1.1(2) and 808.3.1.1(3).

EA = (AF × VT)/DA

(Equation 8-2)

where:

EA	=	Effective aperture.
AF	=	Area of fenestration.
VT	=	Visible transmittance of the fenestration.
DA	=	Daylit area.

TABLE 808.3.1.1
MINIMUM EFFECTIVE APERTURE

1. Sky Type A — more than 75 percent mean sunshine, in accordance with the NOAA Annual Mean Sunshine Percentage Table.
2. Sky Type B — 45 percent to 75 percent mean sunshine, in accordance with the NOAA Annual Mean Sunshine Percentage Table.
3. Sky Type C — less than 45 percent mean sunshine, in accordance with the NOAA Annual Mean Sunshine Percentage Table.

FIGURE 808.3.1.1(1)
DAYLIT AREA ADJACENT TO FENESTRATION IN A WALL

FIGURE 808.3.1.1(2)
DAYLIT AREA ADJACENT UNDER A ROOFTOP MONITOR

FIGURE 808.3.1.1(3)
DAYLIT AREA ADJACENT UNDER A ROOFTOP MONITOR

FIGURE 808.3.1.1(4)
SKY TYPES

The daylit area shall be illuminated by a roof fenestration assembly such as a skylight, sloped glazing or tubular daylighting device that complies with Table 808.3.1.1 and Figure 808.3.1.2. The daylit area extends laterally and longitudinally beyond the glazed opening of the roof fenestration assembly to the nearest 56-inch-high (1422 mm) partition, or up to 0.7 times the height from the floor to the bottom of the rough opening of the daylighting well, whichever is less, as indicated in Figure 808.3.1.2.

FIGURE 808.3.1.2
DAYLIT AREA UNDER A SKYLIGHT