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High Performance Lighting
Improve Energy Efficiency With Solid-State Systems
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According to the Dept. of Energy,
solid-state lighting systems
have the potential to more
than double the efficiency of today’s
systems, an essential component of
meeting its Building Technologies
Program’s energy efficiency goals.
A mix of lighting solutions will be
needed to meet the nation’s near-term and
long-term needs, according to the DOE,
and spectrally enhanced lighting is a simple
strategy that uses existing products
and technology to significantly reduce energy
use in commercial buildings.
Energy consumption for all lighting
in the United States is estimated to be
about 18 percent of the total electricity
generated in the country, according to
the Buildings Energy Data Book.
More than half of the energy is consumed
in the commercial sector,
where lighting coincides with peak
electrical demand and contributes to
a building’s internal heat generation,
increasing air-conditioning load.
The conversion of electricity into
useful light is one of the least efficient
energy conversion processes in
buildings today. The DOE says advanced
lighting technologies can significantly
improve the energy
efficiency of lighting and reduce
building energy consumption and
costs.
The concept behind spectrally enhanced
lighting (SEL): A significant
amount of energy can be saved by using
lamps that have less light output, but
higher correlated color temperature
(CCT). Lamps with higher CCT appear brighter than those with lower CCT, so the
actual light output of higher CCT lamps can
be decreased, while maintaining equivalent
perceived brightness and visual acuity.
When ambient lighting is more like the
color of daylight (more white), our eyes respond
the same as if lighting levels were increased
— the pupils of our eyes get
smaller, spaces seem brighter, and we see
things more clearly.
Thus, energy can be saved because the
actual light output of the higher CCT
lamps can be decreased, while maintaining
equivalent perceived brightness and visual
acuity relative to lower CCT lamps.
Energy savings are achieved by using
lower wattage lamps and/or lower ballast
factor ballasts.
Unlike other energy efficiency strategies,
SEL is not a technology — it’s a different
way to quantify light that can be used with
any type of lighting design to improve energy
performance. Energy savings are
achieved by using high performance and
high CCT lamps coupled with efficient
electronic ballasts.
The DOE says SEL is a market-ready,
cost effective solution for quick energy savings.
It is simple to implement, and can currently be employed in buildings as a cost
effective way to get quick energy savings. It
is non-proprietary, requires no fancy controls
or gadgets, and the energy savings are
significant. In addition, SEL is low risk, and
DOE says there are no known negatives to
installing this type of lighting in commercial
buildings.
An evaluation of lighting retrofits at three
office buildings in California in 2005 conducted
by Pacific Northwest National Laboratory
for the DOE Building Technologies
Program found energy savings are achieved
via lower wattage lamps and/or lower ballast
factor ballasts.
PNNL’s evaluation found that connected
loads due to overhead lighting in the three
buildings decreased by 20 percent to 46 percent
following the retrofit. Horizontal photopic
light levels decreased by 15 percent to 31 percent. Task lighting use did not
change significantly, as indicated by metered
use or in terms of occupants’ reported
use. Finally, occupant ratings of satisfaction
with the lighting did not change significantly
following the retrofits in any of the
three buildings.
Appropriate lamps are available through
many major lamp manufacturers and are
generally no more expensive than traditional
lamps. The predominant light source
used in commercial applications is fluorescent
lighting; the lamps and ballasts used
dictate the efficiency of fluorescent lighting
systems.
Using higher color temperature, fluorescent
lighting and new high-efficiency ballasts
can achieve energy savings of 20-40
percent compared to traditional fluorescent
lighting systems, according to results of the
DOE study, and can be achieved by simple
lamp/ballast retrofits. ❑
Source: “Spectrally Enhanced Lighting
Program Implementation for Energy Savings:
Field Evaluation,” prepared by Pacific
Northwest National Laboratory for
U.S. Department of Energy Office of Energy
Efficiency and Renewable Energy
Building Technologies Program.
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