UFC 3 -520-01
June 10, 2002
Photoelectric Switching Controls . Photoelectric switches should be
provided for exterior dusk-to -dawn lighting, and for interior lighting in daylighted spaces
and not equipped with dimming systems. Use interior detectors that are specifically
designed for the application.
Building Automation and Energy Management Control of Lighting
Building automation systems that provide for the control requirements given above can
be used instead of systems dedicated to lighting control only.
F-13.1.1 Daylighting is defined as the combination of properly designed fenestration
(windows, skylights, or other openings) and the control of electric light to permit interior
illumination from natural light whenever possible.
F-13.1.2 Natural light ("daylight") entering through fenestration is controlled and limited
to provide reasonably even illumination without glare and a minimum of solar heat gain
as compared to no fenestration at all. This requires a carefully designed combination of
building siting, orientation, massing, fenestration design, and glazing material. In some
cases, mechanical daylighting controls might also be needed.
F-13.1.3 The amount and uniformity of natural light is critical in daylighting. Interior
lighting levels must be free of extreme "hot spots" caused by direct sunlight. The
average natural illumination should not be more than 300 percent of the interior lighting
design levels set forth in this document, with the exception of light levels measured
immediately adjacent to the fenestration. Excessive interior daylight illumination can
cause solar heat gain, which can require more cooling energy than the electric energy
saved from lower artificial light levels.
Design Criteria .
F-13.2.1 Buildings Designed for Daylighting. Analyze the performance of any
proposed daylighting system by a point-b y-point interior lighting program with daylight
capabilities, and a building energy analysis program. The proposed building design
must provide the following:
Interior illumination in the majority of the space achieving a minimum of 50 percent
and a maximum of 300 percent of the required illumination on a clear summer day.
Lower energy consumption than the same bui lding with ordinary fenestration and
electric lights operating at full power.
A life cycle cost benefit considering the differential costs of the daylighting systems,
including fenestration, mechanical shading controls, and electric dimming controls.