Page 197 - Solar Power in Building Design The Engineer's Complete Design Resource

OUTDOOR LIGHTING AND SIGNS 167

Minimum lamp efficiency All outdoor fixtures with lamps rated over 100 W must
either have a lamp efficiency of at least 60 lumens per watt (lm/W) or must be controlled
by a motion sensor. Lamp efficiencies are rated by the initial lamp lumens divided by the
rated lamp power (W), without including auxiliary devices such as ballasts.
Fixtures that operate by mercury vapor principles and larger-wattage incandescent
lamps do not meet these efficiency requirements. On the other hand, most linear fluo-
rescent, metal halide, and high-pressure sodium lamps have lamp efficiencies greater
than 60 lm/W and do comply with the requirements.
The minimum lamp efficiency does not apply to lighting regulated by a health or life
safety statute, ordinance, or regulation, which includes, but is not limited to, emergency
lighting. Also excluded are fixtures used around swimming pools; water features;
searchlights or theme lighting used in theme parks, film, or live performances; tempo-
rary outdoor lighting; light-emitting diodes (LED); and neon and cold cathode lighting.

Cutoff luminaires Outdoor luminaires with lamps rated greater than 175 W that
are used in parking lots and other hardscapes, outdoor dining areas, and outdoor sales
areas are required to be fitted with cutoff-type baffles or filters. They must also be
specifically rated as “cutoff” in a photometric test report. A cutoff-type luminaire is
defined as one where no more than 2.5 percent of the light output extends above the
horizon 90 degrees or above the nadir and no more than 10 percent of the light output
is at or above a vertical angle of 80 degrees above the nadir. The nadir is a point in the
direction straight down, as would be indicated by a plumb line. Ninety degrees above
the nadir is horizontal. Eighty degrees above the nadir is 10 degrees below horizontal.

Case study in the application of DC photovoltaic energy The following is
a case study of the application of solar power cogeneration dc electric energy without
conversion to alternating current. The technology discussed is based on electronic
lighting and rotating machinery control devices that operate with direct current. By
eliminating the use of dc-to-ac conversion devices, solar power is applied without the
losses associated with these devices.
To apply directly harvested dc power in electrical wiring, lighting devices and machin-
ery must have specifically designed lighting ballasts and rotary machinery drive controls.
As an example, Nextek Power Systems, a solar power technology development company
located in New York State, has developed specially designed dc fluorescent ballasts and
lighting control systems whereby the dc power harvested from photovoltaic modules is
accumulated, controlled, and distributed from centrally located power routers.
A power router is an electronic dc energy control device that embodies the follow-
ing functions:

■ Routes all dc power harvested by photovoltaic modules as a primary source of energy
and directs it either to the dc lighting control devices or channels the power to a bank
of fast-discharge solar power battery banks for energy storage.
■ In the event of loss of solar dc energy from the photovoltaic solar power system, it
routes conventional electric energy as a secondary source of energy whereby the