22 August 2006
Specify 3000K coated metal halide lamps for exterior applications.
Light Emitting Diodes (LEDs). Lighting Emitting Diodes (LED) will become
increasing important for all types of lighting. LEDs produce a directional narrow beam
of light making it ideal for exit signs, traffic signals, and other directional light source
applications. LED efficacies are increasing constantly, soon making LED luminaires an
effective means for all types of lighting applications. Because LEDs are
monochromatic, white light is difficult to produce unless different colors are combined.
LEDs have extremely long lives (100,000 hours) and consume very little energy. LEDs
are also dimmable.
5-3.7.1 The ideal applications for LEDs are in areas where high brightness is very
important such as exit signs, general signage, step lighting, and directional accent
Considerations for LEDs:
Use LED sources in all exit signs, other lighted information signs and
Consider LED sources for step lighting, nightlights, low brightness wall
sconces, and other low level lighting applications.
High-Pressure Sodium / Low-Pressure Sodium Lamps. High-Pressure
Sodium lamps are typically used for exterior applications. Although high-pressure
sodium lamps have long lives (20,000 hours) and appear to be efficacious, there are
several problems with them. The most important is the lack of short wavelength light
such as blue and green light. As a result, one's peripheral vision under nighttime
exterior lighting conditions, does not respond well to the color of light of the high-
pressure sodium lamps. White light can be two to twenty times more effective for
peripheral vision detection than high-pressure sodium. High-pressure sodium lamps
are not advised for interior applications. Because short wavelength light controls the
pupil, high-pressure sodium lamps cause objects to be "out of focus". In addition, HPS
lamps render color poorly. Refer to Chapter 2, "Lighting Design Considerations" for
lumen effectiveness multipliers. High-pressure sodium lamps can be used where
existing conditions and continuity of source types make it necessary.
5-3.8.1 Low-pressure sodium lamps provide poor nighttime visual acuity and poor
Requirements for high and low pressure sodium lamps:
Do not use low-pressure sodium lamps except for unique applications
such as in sea turtle nesting areas.
Considerations for high-pressure sodium lamps:
Consider white light sources such as induction, metal halide and