ABSTRACT
Section depth refers to the overall distance between perimeter windows and the innermost wall of an occupied space. In multi-story buildings illuminated solely from vertical glazing at the perimeter, the section depth is often the most crucial determinant of whether occupants have access to daylight and views. Beyond providing horizontal illuminance on a workplane, the section depth of a space contributes greatly to visual comfort. Since the human eye tends to adjust to the brightest surfaces in its visual field, a space that is bright at the perimeter and much darker toward the interior, can feel like a cave, even when electrically illuminated at common interior light levels. Additionally, in most cases with narrow section depths, the glazing area could be reduced while maintaining effective daylight illumination. The "back" wall maintains surface brightness in balance with the brightness of the ceiling and floor luminance, and horizontal illumination levels meet commonly accepted daylighting criteria throughout the space.
