I N G S
I N O U T D O O R L I G H T I N G
Little has been written about the opportunities for energy savings in outdoor lighting. The primary reason
is that energy consumed for outdoor lighting is typically off-peak and is therefore not of critical concern to
the energy providers. Since generating off-peak power rarely requires new capital outlays by energy
producers, they lack incentives for encouraging off-peak energy conservation. For energy users however,
the electrical power required for outdoor lighting has become an important component of the energy
budget.
There are three important reasons for users to pay attention to this critical area of energy consumption.
t w o
Many business decisions weigh the trade-off between initial investment vs. life cycle energy savings. In the case of
designing outdoor lighting systems however, these two issues are often in harmony. If a high performing luminaire
optical system can reduce the number of required poles at a site, invariably there will be substantial savings in both
the initial system cost and the life cycle energy consumption.
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I n i t i a l C o s t
The chart to the right illustrates the potential
per pole savings resulting from good design
and high performance equipment. Depending
on site geometry and design criteria, it may
be possible to eliminate 10% or more of the
total pole locations on the site by using high
performance lighting equipment.
Typical initial cost savings resulting from
elimination of each pole location
Trenching
$500
Base
$400
Labor and Equipment
$500
Luminaires/Pole*
$1000
Other Material
$100
Total
$2,500
* Twin 400W metal halide luminaires
with lamps on 25' steel pole
Cover photo courtesy of Site Photometrics. For information about turnkey
outdoor lighting retrofit solutions, contact Site Photometrics at (888)244-SITE. t h r e e
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While off-peak energy costs are certainly lower
than peak energy costs, they can still add up.
If during the lighting design, wattage can be
reduced or fixtures eliminated, cost savings will
continue throughout the life of the project.
In this manual, several strategies will be presented
for reducing energy in outdoor lighting. For
illustration purposes, performance comparisons are
shown which demonstrate different power usage
resulting from the application of different lighting
equipment. In all cases, the lighting equipment
shown is currently available from major US
manufacturers. For copies of actual test data and
calculation methodology consult Gardco Lighting.
The chart at the left, illustrates actual potential
dollar savings that can be achieved by using high
performance lighting equipment and employing
some simple principles of design. The site
parameters, design criteria and lighting equipment
utilized are shown on the referenced pages.
Most electricity generated in America today is
produced from the burning of fossil fuels natural
gas, coal, and oil. These plants all produce
harmful pollutants and CO
2
s. Most scientists
today believe that these CO
2
s contribute
significantly to global warming.
Although nuclear power plants are considerably
cleaner than fossil fuel plants and produce no
CO
2
s, they do create the problem of nuclear
waste disposal. Unfortunately these inevitable
byproducts of energy plants are just as harmful
during off-peak and peak consumption periods.
Energy conservation is unquestionably the best
solution for the environment day or night.
L i f e C y c l e C o s t
E n v i r o n m e n t a l P r o t e c t i o n
SAVINGS EXAMPLES
Small Area with Complex Site Geometry (page 14-15)
Annual energy cost
5� kWh
10� kWh
With inefficient fixtures/lamps
$2003
$4006
With high performance fixtures/lamps
$1577
$3154
Potential savings
$426
$852
Open Parking Area Scenario (pages 10-11) 10� kWh
Annual energy cost
10 Acre Site 100 Acre Site
With inefficient fixtures/lamps
$20,806
$208,055
With high performance fixtures/lamps
$5,224
$52,241
Potential savings
$15,582
$155,814 E N E R G Y S AV I N G T R A D E - O F F S
I N O U T D O O R L I G H T I N G
f o u r
Often times significant energy savings can be realized with a minimal investment of capital and common
sense. Replacing mercury vapor or incandescent sources with metal halide or high pressure sodium will
generally result in reduced energy costs and increased visibility. Installing and maintaining photocontrols,
time clocks, and energy management systems can also achieve extraordinary savings.
However in some cases it may be necessary to consider modifications of the lighting design in order to
achieve the desired energy savings. In other situations, new design criteria or local ordinances may simply
render energy saving objectives unachievable. Nevertheless, even in those situations, intelligent design
can minimize the energy impacts.
Gardco Lighting believes that it is important to candidly address these potential trade-offs and let the owner
determine the relative importance of energy savings to such issues as visibility and quality of illumination.
Frequently older sites are substantially under lit by
todays standards of safety and security. In most of
these cases, it is simply not possible to retrofit these
sites and achieve contemporary lighting standards
without incurring some additional energy
consumption. The important point is that because of
technological advances in lamps, ballasts, and
luminaire optical systems, increasing light levels by
300-400% doesnt require comparable increases in
energy consumption.
I l l u m i n a t i o n L e v e l s
L a m p C o l o r
Courtesy of Venture Lighting
Courtesy of Venture Lighting
Whereas low pressure sodium lighting offers the most energy efficient lighting source commercially available in North
America, the poor color rendering properties make it unsuitable for most commercial applications. Similarly, although
the color rendering characteristics of high pressure sodium lighting are often found to be adequate for roadway
lighting, increasingly metal halide is the preferred source for area illumination. The crisp white light of metal halide
appears to enhance nighttime visibility. Furthermore, with recent advances in metal halide technology, this source now
approaches the efficacy of high pressure sodium.
Older sites often have light levels which are substantially below
contemporary standards. f i v e
There are many proponents of non-cutoff site luminaires who
claim to achieve superior pole spacings and uniformity ratios
with their equipment. The trade-off of these systems however is
often high angle glare and light trespass.
Glare actually reduces nighttime visibility and may therefore
offset any perceived energy efficiencies. Light trespass into
adjacent properties creates ill will (and occasionally litigation)
towards property tenants.
This guide will therefore only be evaluating lighting equipment
which meets the IES cutoff classification. In most cases,
recommended luminaires meet full cutoff meaning they
produce absolutely no light above 90�.
H i g h A n g l e G l a r e , L i g h t T r e s p a s s
S k y P o l l u t i o n
Many of these non-cutoff fixtures which may achieve wider pole spacings also create sky pollution. Dr. David L.
Crawford of the International Dark Sky Association writes:
A priceless part of our human heritage is fading into the night sky. Most Americans are growing up unable to see
the stars their grandparents knew so well. They see the night sky only in pictures or at planetariums. This is true
not only in cities, but also in many suburbs where street lamps and other sources of "light pollution" have obscured
our view of constellations, meteor showers, and planets.
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To address this problem, the IDSA specifically identifies site luminaires which are:
GOOD - Flat-lens shoebox
fixtures come in many forms;
square, rectangular, circular,
etc. All control the light with
internal reflectors. Glare and
light trespass are minimized;
no uplight is produced.
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BAD (sometimes)
The telltale sag lens
gives this luminaire
away as a possible
problem.
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L u m i n a i r e M o u n t i n g H e i g h t
Systems designed with taller poles often allow for wider spacings and reduced energy consumption. Also, some
advocates of these systems point out that the reduced number of poles can create a less cluttered and attractive
site. Nonetheless, some communities have determined that excessive pole heights are out of scale to their
environmental design and they are willing to sacrifice some energy savings to maintain that design integrity. Their
local ordinances often reflect this position.
1) www.darksky.org
Non-Cutoff Luminaire
Cutoff Luminaire
Low mounting heights often result in visual clutter as well as
increased energy use.
Permitting the application of taller poles will allow for wider spacings
resulting in significantly reduced energy consumption. E N E R G Y WA S T E R S
I N O U T D O O R L I G H T I N G
s i x
Frequently a "cookie cutter" approach
is taken to site lighting. Luminaires,
lamps, mounting heights and pole
spacings are all determined from what
was used on a previous job.
Unfortunately this approach often fails
to recognize the unique characteristics
of and the opportunities presented by
the individual site geometry. Taking
advantage of all of the distributions
offered by the luminaire manufacturer
and orienting them appropriately can
often reduce the required number of
pole locations and substantially lower
energy costs over the life of the project.
P o o r L i g h t i n g D e s i g n
To reduce costs,