RESOURCE GUIDE | CEMC-RG-2 | PUBLISHED: OCTOBER 01, 2008
Lighting for Parking Lots and Garages
By Jessica Rivas and Ira Krepchin
Contents
Fast Facts
Overview
Economics
Efficiency
Making the Right Choice
Retrofit Options
Maintaining Performance
Technical Details
Market Outlook
Manufacturers
Success Story
Utility Program Example
For More Information
Got a Question About This Technology?
Notes
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FAST FACTS
• Whiter light sources, such as metal halide (MH), fluorescent, induction, and light-emitting diodes
(LEDs), are preferred in parking lot and garage applications because they offer higher energy
content in the blue-green portion of the spectrum, which enhances the peripheral vision of drivers
and pedestrians under low nighttime illuminance levels. 1
• New fixture classifications have replaced the old cutoff designations with requirements that set
limits on backlight, uplight, and glare (BUG).
• Induction lamps can start at temperatures as low as –40° Fahrenheit (F) with no delay and operate
at those temperatures without significant loss of lumens.
• Rapid advances in the performance of LED products for parking lots and parking garages have led
the U.S. Department of Energy (DOE) to add Energy Star specifications for those applications.
• In practice, fixture efficiency can make a big difference in a lighting system’s overall efficiency—a
fixture with an efficiency of 90 percent will deliver 50 percent more of its light than one with an
efficiency of only 60 percent.
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OVERVIEW
Well-designed lighting for parking lots and garages is cost-effective, efficient, and enhances the safety
of drivers and pedestrians by directing light where it is needed, minimizing glare, distributing
illumination evenly, and reducing light trespass (light spilling over where it is not wanted or needed).
The most common lamps used for outdoor lighting are high-intensity discharge (HID) sources—MH and
high-pressure sodium (HPS). In recent years, fluorescent lamps, compact fluorescent lamps (CFLs), and
induction lamps have become viable sources for outdoor lighting as well, offering good color quality and
better control options than HID sources. LEDs are becoming a good choice as well because costs keep
coming down and performance continues to improve. Regardless of the light source, however, there are
four important points to remember when designing exterior lighting:
• Determine the appropriate illumination level. Many outdoor areas are overlit—an average of one
foot-candle (or less) is usually sufficient. For more information, refer to the IESNA Lighting
Handbook and IES RP-20-98 Lighting for Parking Facilities published by the Illuminating Engineering
Society of North America (IESNA).
• Choose suitable fixtures. To reduce light pollution, use fixtures that do not spread light above the
horizontal plane. Fixtures should also minimize glare and provide appropriate levels of uniformity.
• Use whiter light sources. Recent research, although not yet codified, shows that the whiter light
produced by MH, fluorescent, induction, and LED sources enables pedestrians and drivers to see
better than under an equivalent amount of yellowish light from sodium lamps.
• Provide controls. Install timers, light sensors, motion detectors, or pager controls to run the lights
only when needed or to dim them accordingly.
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ECONOMICS
The factors that enter into the cost-effectiveness of a lighting solution for parking areas include the cost
of the light source and fixtures, the efficiency of the system (see Efficiency), lamp life and its impact on
maintenance costs (see Making the Right Choice), and the light levels provided. The following example
illustrates the major considerations that go into an analysis of the economics of a parking lot or outdoor
area lighting project.
Figure 1 compares two designs for a government laboratory parking lot. 2 The conventional design
called for 60 250-watt (W) HPS lamps to provide an average illuminance of about 2 foot-candles—more
light than necessary for this application. The efficient design uses 24 175-W MH lamps for an average
illuminance of 1 foot-candle and requires fewer poles and luminaires than the conventional design.
FIGURE 1: Comparing two parking lot designs
A government laboratory surrounded by residential neighborhoods commissioned two designs for its
new parking lot. The conventional design (A) used 250-watt (W) high-pressure sodium lamps in fullcutoff cobra head fixtures. There were five rows and seven columns of 30-foot-tall luminaires. The
outer columns used one luminaire per pole and the five inner columns used two. The average
illuminance was about 2 foot-candles and the minimum was about 0.5 foot-candles. The ratio of
maximum to minimum illuminance was 7:1. The alternative design (B) uses 175-W metal-halide
(MH) lamps. The “hockey puck” cutoff luminaires distribute light more efficiently than the cobra
heads in the conventional design, allowing fewer poles and luminaires to be used. In this design,
there are only four rows and four columns. As in the conventional design, the outer columns use one
luminaire per pole and the inner columns use two luminaires per pole (24 luminaires and 16 poles
total), and the poles are 30 feet tall. The average illuminance is about 1 foot-candle, the minimum is
about 0.3 foot-candles, and the ratio of maximum to minimum illuminance is about 9:1. Even better
performance can be achieved by using 150-W MH lamps with electronic ballasts, induction lamps, or
high-quality light-emitting diode fixtures.
Comparing the two designs (Table 1), we see that this is made possible by using higher-quality
luminaires with better light distribution. First costs are lower in the efficient design and energy costs are
drastically reduced thanks to the lower-wattage lamps. Light levels are also lower in the efficient design,
which meets IESNA specifications. MH lights provide more light in the blue part of the spectrum where,
at low light levels, the eye is more sensitive, and therefore less light is needed. For a more in-depth
discussion of vision and the spectral content of a light source see Technical Details.
TABLE 1: Economic comparison of conventional versus efficient parking lot design
The efficient design uses fewer poles and luminaires than the conventional design. This is made
possible by using higher-quality luminaires with better light distribution. Although the metal-halide
(MH) lamps and luminaires used in the efficient design cost more per unit, using fewer units reduces
overall first costs by about 40 percent. Energy costs fall by about 70 percent in the efficient design
due to fewer and lower-wattage lamps. Maintenance costs are slightly higher for the efficient design
because the MH lamps have a shorter life and must be replaced more frequently. Light sources with
longer life, such as induction lamps and light-emitting diodes, would significantly reduce
maintenance costs.
The most expensive outdoor lighting systems, in terms of first cost, are those that use induction lamps
and those that use LEDs. An induction lamp fixture costs about $450 and replacement lamps run about
$200. However, the lamps can last up to 100,000 hours and in some cases the maintenance savings can
lead to reduced life-cycle costs. (For a cost-effectiveness example comparing MH and induction lighting,
see Success Story.)
LED fixtures are even more expensive—$525 to $725 in one test installation sponsored by the DOE,
leading to a long payback period compared to an HPS system. 3 But LED costs are coming down and
LED systems are becoming competitive. For another parking lot example, in which LEDs had a payback
of about six years compared to an MH system, see our Resource Guide “Light-Emitting Diodes.”
In some garage and parking lot applications, fluorescent lamps may be a cost-effective solution. A
retrofit from MH to fluorescent lighting in a parking garage in Boston, Massachusetts, is expected to cut
demand by 30 kilowatts (kW) and save 261,000 kilowatt-hours (kWh) per year. The fluorescent system
will use the same number of fixtures—235—but each one will draw 78 W rather than the 205 W drawn
by each fixture in the existing lamp and ballast combination. The fluorescent fixtures are insulated and
use low-temperature ballasts to ensure good cold-weather operation. 4
When paired with motion detectors, fluorescent lamps, induction lamps, and LEDs become even more
cost-effective. They provide nearly instant-on operation, whereas HID sources need several minutes to
warm up, making them unsuitable for on/off control with motion detectors.
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EFFICIENCY
The efficiency of a lighting system for parking lots or garages depends on the light source, the fixture in
which it is housed, and controls that can dim or turn off the lights when they are not needed.
Light Sources
Different lamps have different efficacies (Table 2) and that data should be taken into account, along
with life span and color quality, when choosing a light source. Common light sources for parking lot and
garage applications include:
• Fluorescent. Fluorescent lamps—linear and CFL—offer good efficiency, long life, and good color
quality. With low-temperature ballasts and enclosed fixtures, fluorescent systems are a good option
for outdoor lighting. Read the E Source report “Lighting Tips and Pointers” for more information.
• Metal halide. MH lamps offer good efficiency and life span (but not as good as HPS). They provide a
nice white light, with ceramic MH lamps offering better color quality than quartz lamps.
• Low-pressure sodium. LPS lamps offer very high efficiency, but poor color, and are not commonly
used. They are mainly used for lighting near astronomical observatories because the monochromatic
light is easy to filter out.
• High-pressure sodium. HPS lamps have been one of the most common choices for outdoor lighting
since the 1970s. They offer good efficiency and long life, but not everyone likes the yellowish color.
Many designers claim that you can use lower wattages with whiter lamps (see Technical Details for
a comprehensive explanation).
• Induction. Induction lamps offer long life (up to 100,000 hours), very good color, and efficiency
similar to that of MH. They are expensive, but maintenance savings, especially in hard to-access
locations, can lead to reduced life-cycle costs (see Economics).
• Light-emitting diodes. In terms of performance, LEDs have recently become a viable option for
parking lot and garage lighting. They can be expensive, but prices have been coming down. LEDs
are improving in efficacy, but it is currently not as high as other sources. Because the light is
directional, however, the fixtures can be very efficient and can provide good light distribution,
leading to energy savings in some applications. Our “Light-Emitting Diodes” Resource Guide
provides more information.
TABLE 2: A comparison of lamp efficacies and color quality
Efficacy (defined as lumens per watt) for light sources most commonly used in parking lots and
garages covers a wide range. For a given lamp type, higher wattage generally means higher
efficacy, except in the case of light-emitting diodes (LEDs). And in general, the higher the color
rendering index the more natural the source appears and the richer colors appear. Low- and highpressure sodium lamps offer high efficacy, but poor color quality.
Fixtures
An efficient fixture directs as much light as possible where it is needed. A well-designed parking lot
lighting system should use luminaires that direct light downward and minimize glare and light trespass.
Although glare can simply be a nuisance, in severe cases it can pose a significant danger by
momentarily blinding drivers and pedestrians.
Until recently, IESNA classified outdoor luminaires in terms of “cutoff”—the amount of light emitted
above the luminaire, which affects the amount of glare and light pollution. The old definitions are
included here because they are still used by some manufacturers and designers:
• Noncutoff. Spraying light everywhere, noncutoff fixtures produce extreme light pollution—glare and
light trespass—and waste energy.
• Semicutoff. The most commonly used luminaires for street and parking lot lighting applications are
semicutoff fixtures, including the dropped-lens “cobra head.” Nevertheless, they cause considerable
light pollution and are more appropriate for commercial districts where light trespass is less of a
concern than for neighborhood settings.
• Cutoff. Directing most of the light downward, cutoff luminaires cause minimal light pollution.
• Full cutoff. These luminaires emit no light above the horizontal and cause the least light pollution.
The new IESNA designation does away with the cutoff terminology and defines the light distribution and
optical control of outdoor area and roadway lighting luminaires by the amount of light that they emit
into different zones, expressed as a percentage of the total lamp output. These classifications were
established to allow lighting designers to fine-tune their choices of fixtures based on the demands of
different applications. The classifications are described in IESNA’s Technical Memorandum TM-15-07,
“Luminaire Classification System for Outdoor Luminaires.” 5
These classifications are being incorporated into a Model Lighting Ordinance (MLO) being developed by
IESNA and the International Dark-Sky Association (IDA). The MLO recommends fixtures for different
applications based on how much backlight, uplight, and glare they produce. In this system, known by
the acronym BUG, backlight is a measure of light trespass, uplight is an indication of light pollution (also
called sky glow), and glare is intense light that interferes with vision. The MLO sets limits for each
component depending on the zone in which the system is to be installed. Zones have been defined as
regions of no light (LZ0), low (LZ1), moderate (LZ2), moderately high (LZ3), and high light (LZ4). 6
In addition to pole-mounted luminaires, many parking lots use wall-mounted fixtures, which are
typically very inefficient, provide nonuniform light distribution, and don’t have any glare control. In
recent years, products have been developed that use advanced optics to minimize glare, increase fixture
efficiency, and improve light distribution. You can read more about two new fixtures with advanced
optics in the Technical Brief “High Hopes for Low-Glare Outdoor Luminaire.”
Finally, LEDs have potential for parking lots and garages because the light output is easy to direct. A
well-designed LED fixture provides an even distribution of light with minimal light pollution, although
some designers have raised concerns about glare from LED fixtures. More about those concerns can be
found in Market Outlook.
Controls
The MLO being developed by IESNA and the IDA recommends the use of controls to save energy and
reduce unwanted light. Officials are encouraged to set hours during which outdoor lighting can be
dimmed or extinguished. This not only reduces light pollution, but also saves energy during low-activity
times.
Automatic controls cut energy use by turning lights off during the day and turning them off or dimming
them during other periods of little or no activity. Controls may be centralized, with all fixtures controlled
by a single photocell or timer, or linked to a building automation system. An alternative approach
features a photocell for each fixture. The photocell controls the luminaire, so it operates only when the
ambient light falls below a certain threshold. The luminaire operates from dusk to dawn and during lowlight conditions such as may occur during a storm. More advanced systems could sense light levels and
adjust the lamp output to account for conditions such as snow cover and wet pavement that increase
the reflectivity of the surroundings.
Motion detectors can also be used in some applications to make sure the lights only go on when needed.
Fluorescent, induction, and LED systems can easily be operated with motion detectors, whereas MH and
HPS lamps cannot because they take too long to warm up. However, motion detectors can be used with
MH and HPS lamps for dimming by up to 50 percent. For more information about HID dimming systems,
see our Resource Guide “High-Bay Lighting: HID versus HIF.”
The improved controllability of induction and LED light sources is also leading lighting professionals to
develop adaptive lighting standards. Such standards would set different lighting level requirements
depending on the time of day, amount of activity, or other local conditions.
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MAKING THE RIGHT CHOICE
Efficient parking lot and garage lighting design takes several factors into account: ideal light levels,
appropriate color, minimized light pollution, anticipated ambient temperatures, and cost-effectiveness.
Light Levels
Outdoor lighting levels contribute to the safety of drivers and pedestrians and to the security of
buildings by exposing intruders’ movements and permitting occupants to move safely to cars. A visually
safe outdoor environment will not expose people to excessive levels of glare or large differences in
illuminance levels. Parking lot or garage light levels, or foot-candle illuminance levels, may depend on
local ordinances, but can generally be fairly low. The guidelines laid out by IESNA suggest 0.5 to 5.0
foot-candles, depending on the level of activity and the potential hazards. Typically, an average of 1
foot-candle (or less) is sufficient. For more information, refer to IES RP-20-98 Lighting for Parking
Facilities or Chapter 10 of the IESNA Lighting Handbook. 7 In the future, look for the development of
adaptive lighting standards.
Color
For applications such as parking lots and outdoor walkways, whiter light sources—such as MH,
fluorescent, induction, and LEDs—are often preferable because they offer higher energy content in the
blue-green portion of the spectrum, which enhances the peripheral vision of drivers and pedestrians
under low nighttime illuminance levels. 8 Technical Details provides a more thorough explanation of the
science behind light color.
Light Pollution
Light pollution is a major concern in designing exterior lighting. Outdoor lighting ordinances and codes
encourage the use of lighting that reduces sky glow, glare, light trespass, and energy waste. Many
codes are now including the concept of e-zones to distinguish between different types of lighting areas.
For example, near national or state parks, wildlife refuges, or astronomical observatories, lighting levels
should be much lower than in city centers. The ordinances and community standards vary and local
zoning departments should be contacted before implementing an outdoor lighting project. For more
information on light pollution, visit the International Dark-Sky Association.
Temperature Considerations
Because parking lots and garages may experience temperature extremes, it’s important to consider how
temperature affects lighting equipment performance.
Ballast starting temperature. The ballast selected for an outdoor application must be rated to start at
the lowest expected temperature. Most outdoor lighting today, especially in cold areas, is done with HID
lamps (HPS or MH). A HID source had an edge over a fluorescent in its capability for low-temperature
starting, but that capability is now being matched by some fluorescent systems with low-temperature
electronic ballasts. Some manufacturers offer ballasts with starting temperatures of –20°F, and specialty
ballasts are available with starting temperatures as low as –35°F. CFL ballasts are rated to start lamps
at temperatures as low as –15°F. Fluorescent electrodeless lamps, or induction lamps, can start at
temperatures as low as –40°F with no delay and operate at those temperatures without significant loss
of lumens.
Lamp performance as a function of temperature. HID lamp output varies little with temperature
because any changes in temperature that a lamp experiences are very small compared to the lamp’s
operating temperature of more than 1,400°F. For other light sources, temperature can have a big effect.
The output of fluorescent lamps, which operate at about 100°F, drops off steeply above and below the
optimum temperature (Figure 2). 9
FIGURE 2: Fluorescent lamp output varies with temperature
The output of fluorescent lamps varies with temperature. T5 and T8 lamps are optimized around
different temperatures. T8s lose 20 percent of light output when the ambient air temperature in the
lamp compartment reaches about 52° or 111° Fahrenheit (F). The same is true for high-output T5s
at about 70° and 134°F. Metal halide output varies little with temperature.
For cold temperatures, that effect can be mitigated by using enclosed fixtures which keep a blanket of
warm air around the lamps. High temperatures can also decrease the output of fluorescent lamps and
shorten the life of fluorescent and HID ballasts. If high temperatures are expected, check with the
ballast manufacturer for the maximum temperature rating for the ballast case. High temperatures are
not generally a concern for outdoor areas because the lamps typically operate at night when
temperatures are cooler. For LEDs, high temperatures will degrade output and life, but cold
temperatures are not a problem—in fact, LEDs perform better in cold temperatures (see Technical
Details).
Lifetimes and Cost-effectiveness
Lamp life will have a big effect on the cost-effectiveness of a lighting system because of its effect on
maintenance costs. For most lamps, the rated life of a lamp is the time at which 50 percent of a group
can be expected to have burned out. Stated another way, after a group of lamps has operated for its
rated life, half of the lamps will have burned out—not all, as is commonly assumed. However, LEDs
generally don’t fail outright, but gradually fade away. LED life is defined as the point at which output
drops below 70 percent of the original output. Table 3 compares the rated life of various light sources.
TABLE 3: Rated life of various light sources
The rated life of a lamp is the time at which 50 percent of a group can be expected to have burned
out or, for light-emitting diodes (LEDs), the time at which light output has dropped to 70 percent of
its initial value. Induction lamps provide the longest life span and compact fluorescent lamps (CFLs)
the shortest.
HID sources. MH lamps used in outdoor lighting applications typically have a rated life of 20,000 hours
while HPS lamps are rated at 24,000 hours. The average rated life of HID lamps is based on 10 hours of
operation per start.
Full-size fluorescent lamps. Full-sizefluorescent lamps are typically rated from 20,000 to 40,000
hours of life, depending on lamp type and ballast, although one new product, a T5 lamp from Kumho
Electric USA Inc., has a rating of more than 80,000 hours. 10 Fluorescent lamp life is based on 3 hours
of continuous operation per start. In applications where the average burn cycle is longer than the
standard rating cycle of 3 hours per start, the field lifetime of fluorescent lamps is longer than the rated
life. Figure 3 shows typical lamp life as a function of hours per start. 11
FIGURE 3: Lamp life versus run time per start
Fluorescent lamp life is very sensitive to the number of times the lamp is started—the longer the on
portion of the on/off duty cycle, the longer the lamp life. In short-duty-cycle applications, the right
type of ballast can dramatically extend lamp life. The 700-series lamps are commodity-grade T8s
and the XPS lamps fall in the high-performance T8 category.
Induction lamps. The biggest benefit of an induction lamp is its long life, which can be up to 100,000
hours because there are no electrodes to wear out or filaments to burn up. With no electrodes that
could fail, the lamps can also endure an almost unlimited number of starts—more than 1 million in one
case. 12 When an induction lamp fails, it is usually because the phosphors slowly degrade until the
lamp’s output is no longer sufficient. Induction lamp systems include a power generator, which used to
be the weak link, but technology has improved in recent years and now the generator typically lasts as
long as the lamps.
Although induction lamps carry a higher initial cost, in applications where maintenance is difficult and
time-consuming the payback period can be just a few years. The major savings come from the long
lamp life, which can reduce maintenance costs, especially in hard-to-reach areas. The simple act of
changing a light bulb in a parking lot or garage could require special equipment, extra traffic measures,
and cost hundreds of dollars.
Long lamp life provides other benefits including a reduction in solid waste and toxic mercury that enters
the waste stream. For example, as many as 10 MH lamps in a given application might be discarded
before a single induction lamp fails. Long life also affects overall safety: Less frequent lamp outages
means greater safety.
CFLs. Most low-power CFLs have rated lives of about 10,000 hours, whereas higher-power T5 CFLs can
have rated lives as long as 20,000 hours. CFLs are rated on the basis of a 3-hours-on, 20-minutes-off
operating cycle. The life of CFLs can be dramatically reduced by frequent cycling, or it can be extended
beyond the rated life by continuous operation.
LEDs. Although LED vendors frequently cite lifetimes of 100,000 hours, real-world applications generally
range from 35,000 to 50,000 hours of use before dropping below 70 percent of initial brightness. 13
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RETROFIT OPTIONS
Any garage or parking lot that suffers from poor light distribution or uses inefficient light sources—such
as incandescent, mercury-vapor (MV), or old probe-start MH lamps—should be retrofit with a more
efficient light source. It will almost always be cost-effective to change out these inefficient lamps, but
the most cost-effective choice will depend on application specifics, as discussed in Economics. For
ballasted lamps, ballasts usually have to be changed as well to ensure compatibility. Fixtures are also
often changed to be sure that the right light distribution is obtained with the new light source and to
eliminate any glare or light trespass problems.
Specific retrofit options are available for MV lamps. (Under the federal Energy Policy Act [EPAct] of
2005, mercury vapor lamp ballast manufacturing has been phased out.) These options include:
• HPS retrofits. Special HPS lamps are available that can run directly on MV ballasts of similar
wattage. This makes for an easy screw-in retrofit, but light distribution must be considered because
the new HPS lamps will put out more light.
• MH retrofits. Special MH lamps are also available that will operate on 400- and 1,000-W MV ballasts.
These lamps do not provide as much light as HPS retrofits, but they still provide more light than the
original MV lamps. The color quality of the MH light is better than either the original MV lamps or an
HPS retrofit.
For systems that use old probe-start MH technology, a pulse-start MH lamp is a good option—it is more
efficient, last longer, and its output degrades more slowly. Electronic ballasts are also now available to
boost the efficiency of MH and HPS systems. For more information, see our Resource Guide “High-Bay
Lighting: HID versus HIF.”
Fluorescent lighting is a good option for parking garage retrofits. Thousands of parking garages across
the country use MH or HPS lamps, and the result is often poor-quality, inefficient lighting. Most HID
garage lights have poor fixture efficiency and low lamp/ballast efficacy. Although no data is available to
quantify the state of these lighting systems, systems with uneven light distribution and poor color have
created a general dissatisfaction with conditions and contributed to security concerns. 14 Fluorescent
lighting was chosen to replace HID lighting in a parking garage in Boston, Massachusetts, and the
system is expected to cut demand by 30 kW and save 261,000 kWh per year. The fluorescent system
will use the same number of fixtures—235—but each one will draw 78 W rather than the 205 W drawn
by each fixture in the existing lamp and ballast combination.
Induction lamps and LEDs are also an option for retrofitting in garages and parking lots, but they may
not always be cost-effective. If considering LEDs, make sure the fixtures are well-designed and that
manufacturers are not making exaggerated claims about performance (see Market Outlook).
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MAINTAINING PERFORMANCE
Lamp output decreases over time due to dirt accumulating on the fixtures and the lamp phosphors
degrading, and lamps burn out—scenarios that reduce safety. Maintaining lighting systems is important,
but costs can be high because the mounting heights often require special equipment to access the
luminaires. Labeling fixtures, group relamping, and proper lamp disposal are maintenance steps to
minimize costs and increase safety.
Labeling
Proper labeling is helpful in fixture maintenance plans. “Parking Lot and Area Luminaires,” a report from
the National Lighting Product Information Program (NLPIP), explains that parking lot fixtures with
inadequate labels make it difficult for maintenance personnel to determine the correct replacement
lamps, ballasts, or luminaires. The report recommends that fixtures comply with the American National
Standard for Roadway and Area Lighting Equipment (ANSI C136.22), which calls for the manufacturer to
provide the manufacturer’s name, luminaire catalog number, input voltage, maximum line current,
ballast type, lamp type and wattage, wiring diagram, and date of manufacture on the luminaire. 15
Spot Versus Group Relamping
There are a variety of reasons to practice group relamping (replacing lamps on a regular schedule,
typically at 60 to 80 percent of rated life) rather than spot relamping (lamps are only replaced when
they burn out). Most of these reasons apply to fluorescent and HID lamps rather than incandescent
lamps, which have much shorter lifetimes and less lumen depreciation.
• On a per-lamp basis, group relamping requires significantly less labor than spot relamping. A single
expired lamp can take a worker up to 40 minutes to replace—the worker must fetch the new lamp,
set up equipment, and install the lamp. Having all the materials on hand and moving systematically
from one luminaire to the next reduces labor time to about 10 minutes per lamp. 16 Group
relamping also reduces disruption of normal activities because it’s normally done outside of business
hours.
• Group relamping is an easy task to schedule and delegate to outside contractors who have special
equipment, such as telescoping scaffolding, ultrasonic lens and louver cleaners, and training. This
reduces administrative overhead by enabling the facility to staff a smaller maintenance crew for
occasional spot relamping and other tasks.
• Group relamping provides brighter and more uniform lighting, getting rid of lamps before they reach
the end of the lumen depreciation curve. This can also pay direct energy benefits because the
designer can use a smaller safety factor—that is less extra light is needed initially to make sure that
adequate light is still provided by the time the lamps are changed.
• Group relamping allows standardization among the replacement lamps, reducing the probability of
mixing incompatible lamps, such as those with different color temperatures.
Economic comparisons show that group relamping typically has higher lamp costs than spot relamping,
but lower labor costs. Table 4 compares the two relamping methods and reveals a substantial 43
percent overall savings from group relamping. This type of calculation is heavily dependent on the
difference in labor costs between group and spot relamping. For example, if the group relamping cost of
$1.90 per lamp jumps to $4.75, the balance tips in favor of spot relamping. Remember, however, that
there are also noneconomic benefits of group relamping.
TABLE 4: Economics of spot versus group relamping for 1,000 3-lamp T8 lensed troffers
Group relamping has higher lamp costs, but much lower labor costs, providing, in this case, a 43
percent overall savings. Group relamping also provides additional benefits in improved lighting
quality and facility management savings.
To increase efficiency, other maintenance activities can be combined with group relamping, such as
ballast and reflector inspection and lens cleaning. Group relamping also provides an opportunity for
retrofitting reflectors, lamps, ballasts, or lenses as necessary.
Disposal
The final maintenance issue for lamps and ballasts is disposal. Proper handling of fluorescent, induction,
and HID lamps (all of which contain mercury) protects both the environment and the workers handling
the lamps. Improper disposal of fluorescent and HID lamps may be illegal, so make sure that
maintenance personnel understand current lamp disposal regulations and provide proper containers for
old lamps that are being held prior to disposal. See Chapter 3 of the E Source Lighting Technology Atlas
for a complete discussion of lamp and ballast disposal.
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TECHNICAL DETAILS
Consider a fixture’s properties (such as efficiency and light distribution) and the spectral content of the
light source when evaluating lighting options for parking lot and garage applications. For technical
details specific to HID and fluorescent lamps, such as lumen depreciation, dimming options, start-up
and restrike times, glare, and mercury content, see our Resource Guides “High-Bay Lighting: HID
versus HIF,” “High-Performance T8 Fluorescent Lamps,” and “Compact Fluorescent Lamps.”
Fixture properties. Many outdoor lighting projects use efficient sources (lamp plus ballast) but fail to
deliver the light in an efficient manner. It’s essential to consider the efficiency and light distribution of
the fixture to get the most benefit from an efficient source. Fixture efficiency is the measure of how
much of a source’s light is actually emitted from the fixture. Measurements can vary from a low
efficiency of about 50 percent to a high of nearly 100 percent. In practice, fixture efficiency can make a
big difference in a lighting system’s overall efficiency—a fixture with an efficiency of 90 percent will
deliver 50 percent more of the light from a source than one with an efficiency of only 60 percent.
When evaluating fixture efficiency, make sure that the testing was done according to procedures
approved by lighting industry experts, like IESNA. Testing by independent labs is usually more reliable
than that of manufacturers and less likely to be “doctored” to achieve a higher rating.
In addition to examining a fixture’s efficiency, designers should pay attention to its pattern of light
distribution. For parking lot light fixtures, both vertical and horizontal light distribution patterns are
important for preventing light pollution—glare, light trespass, and sky glow—and ensuring the safety of
drivers and pedestrians. Use photometric data for all fixtures under consideration to determine the best
lamp wattages, mounting heights, and spacing between fixtures to meet the project’s illumination
requirements. Read the NLPIP report “Parking Lot and Area Luminaires” for more information.
Spectral content. The spectral, or color, content of a light source affects visibility at night and should
influence the choice of light sources and lamp wattages. At daytime light levels, the cone photoreceptors
in the eye play a dominant role in vision—a phenomenon known as photopic vision because the cones
are sensitive to light in the photopic (green-yellow) region of the spectrum. At low light levels, only rods
contribute to vision—known as scotopic vision because the rods are sensitive to light in the scotopic
(blue-green) region. Figure 4 compares the two types of eye sensitivity.
FIGURE 4: Photopic and scotopic ranges of eye sensitivity
Cones are most receptive to light in the photopic region, whereas rods are most receptive to light in
the scotopic region. Light sources that deliver more light in the scotopic region may be able to
deliver the same level of visual service while reducing energy use.
At light levels appropriate for outdoor area lighting, both rods and cones are active. This is known as
mesopic vision. Because the rods are more sensitive to bluer light than the cones, as light levels
decrease, the eye’s spectral sensitivity shifts toward those shorter wavelengths (toward the blue end of
the spectrum). Whiter lights with high color temperatures have more energy content in these shorter
wavelengths. To quantify these effects, researchers are developing “luminous effectiveness multipliers”
for different types of light sources. 17
For example, consider a comparison of HPS and MH lamps. An HPS source puts out more lumens per W
in the photopic region than an MH lamp, but in mesopic conditions, the MH source is more effective.
Some lighting specifiers and designers have used arguments based on those observations to justify
steps like replacing 250-W HPS lamps with 175-W MH lamps in an outdoor setting. The resulting system
uses less energy while providing light that is more useful to pedestrians and drivers. In a recent field
test, the Lighting Research Center found that 55-W induction lamps or 70-W ceramic MH lamps with a
color temperature of 6,500 kelvins (K) could replace 100-W HPS lamps. However, only the induction
lighting approach proved cost-effective. 18
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MARKET OUTLOOK
Although HID lighting has dominated parking lot and garage applications in recent years, LEDs are
poised to make inroads. As LEDs continue to increase in efficiency and decrease in cost, they will be
used in increasing numbers in parking lot and streetlighting applications, which account for 7 percent of
all American electric energy consumption and represent a large potential market for LED technology. 19
LEDs—Getting Better All the Time
Outdoor applications are an up-and-coming market for LEDs for several reasons. The first involves the
way LEDs reject heat. Conventional light sources feel hot to the touch because they dissipate heat as
infrared radiation. LEDs are cool to the touch because heat is dissipated through a solid heat sink. This
is difficult to do indoors where space is at a premium and temperature must be managed. Outdoor
fixtures have space for very large heat sinks and they generally operate at night when the air is cooler.
Because heat dissipation is vital to LED performance, they operate at higher efficiencies and last longer
in outdoor applications.
Another reason LEDs are increasing in popularity is that output is directional, making it easier to reduce
light pollution and point the light where it’s needed. LEDs are also compatible with dimming controls and
motion detectors, allowing reduced energy use when a facility is not in use. LED proponents tout the
ability to vary the color of the LED output to provide the best quality of light for a given time of night.
For more information, read our Resource Guide “Light-Emitting Diodes.”
The DOE recently published the results of two field studies: The first, “Demonstration Assessment of
Light Emitting Diode (LED) Street Lighting” (PDF), with assistance from Pacific Gas and Electric Co.,
assessed street lights on public roadways in Oakland, California; and the second, “Demonstration
Assessment of Light Emitting Diode (LED) Walkway Lighting” (PDF), examined walkway lights at Federal
Aviation Administration facilities in New Jersey. The reports show that compared to HPS lamps, the LEDs
used less energy and provided proportionately less light, which, according to the report, was adequate
because it was well distributed. However, the payback for LEDs was longer than that of HPS lamps.
Areas of Concern
Several words of caution regarding LEDs: First, for all applications, LED products are of uneven quality
and manufacturers often make exaggerated claims about performance—a situation reminiscent of the
early days of CFLs when many consumers were left with a bad impression after negative experiences
with early products. Early CFLs were costly, often provided poor light quality, gave less light than
expected, and failed prematurely. 20 The DOE and other interested parties are determined to avoid
these pitfalls with LEDs.
The DOE has established robust and standardized testing programs and introduced an Energy Star
specification for LEDs. Initially, Energy Star identified seven types of applications in which the DOE
anticipates the greatest consumer acceptance. Rapid advances in the quality of products for parking lots
and garages have led the DOE to consider adding Energy Star categories for those applications as well.
For more information, visit the DOE’s Standards Development for Solid-State Lighting web page.
Another concern is light pollution. Because the light source is much smaller with LEDs than with typical
HPS or MH sources, different measures are required in fixture design to reduce glare. Also, LED
technology is such that lamps are most efficient at high color temperatures, therefore a number of
installations have used 6,500 K lamps. Light at that temperature has a great deal of blue content, which
scatters easily (explaining why the sky is blue) and contributes greatly to sky glow.
In addition, there is speculation that wildlife may be adversely affected by the 6,500 K lamps. Naturally
occurring night illuminance, such as the full moon, has a color temperature of about 4,100 K. Ongoing
research is addressing both issues. 21
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MANUFACTURERS
Parking Lot and Garage Fixtures
The following is a partial list of manufacturers that offer parking lot and garage fixtures:
• Amerillum Corp.
• Full Spectrum Solutions Inc.
• Lumax Industries
Induction Lamps
Two leading lamp manufacturers produce induction lamps for outdoor applications:
• OSRAM SYLVANIA: ICETRON electrodeless lamp
• Philips makes the QL Induction Lighting System
LEDs
Dozens of companies produce LED lamps and luminaires, including the following leading manufacturers
(for a more complete listing, visit the Lightfair LED vendor list):
• BetaLED
• IntenCity Lighting Inc.
• Ledlight Group
• Lumecon
• Stanley Electric Co.
• LEDtronics Inc.
• LightPower Inc.
• Lighting Science Group Corp.
• Elumen
• GE Lighting
Outdoor Lighting Controls
The following is a partial list of manufacturers that offer outdoor lighting control products:
• Ledalite
• Leviton
• Lightolier Controls
• Lutron Electronics Co. Inc.
• Watt Stopper/Legrand
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SUCCESS STORY
In 2001, City of Fort Collins Utilities found electrodeless lamps to be a cost-effective lighting upgrade in
a parking garage in Fort Collins, Colorado. Both maintenance and energy savings from the use of
electrodeless lamps resulted in a predicted return on investment of 21 percent and an average simple
payback of less than five years compared with a MH base case (Table 5). 22 The facility has been
operating since March 2001 with no problems reported. Light quality and distribution are reportedly
better than when HPS lamps were in use. However, not all of that effect can be attributed to the
induction lighting—the ceiling and walls were also painted white to increase reflectivity and improve light
distribution. 23 For a success story about LEDs replacing MH lamps in a British Columbia health center
parking lot, see our Resource Guide “Light-Emitting Diodes.”
TABLE 5: Cost-effectiveness calculation for electrodeless lamps
Metal halide (MH) lamps and electrodeless alternatives are compared for an actual installation of
electrodeless lamps at a municipal parking garage in Fort Collins, Colorado. The eye uses light
provided by conventional MH lamps less effectively than it uses light from electrodeless lamps, so
the analysts accounted for pupil lumens when determining the number of lamps required. Therefore,
the wattages for MH lamps used in the analysis were higher than those for the electrodeless lamps.
A total of 135 luminaires were considered: 53 that are controlled by photosensors and 82 that are
on 24 hours per day. Reductions in energy and maintenance costs led to a payback of less than five
years.
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UTILITY PROGRAM EXAMPLE
Encouraging the installation of high-efficiency parking lot and garage lighting can help utilities with
strategic energy-efficiency programs and help commercial customers reduce energy bills. Rebates play a
big role by providing companies an extra incentive to purchase efficient systems. For example,
Wisconsin’s Focus on Energy program provides information, resources, and financial incentives to the
state’s residents and businesses.
One financial incentive is a prescriptive rebate targeted at apartment owners/operators and
condominium owners associations. The program pays $20 per fixture for changing out HID systems in
covered parking areas with high-performance T8 systems. According to Liesel Schulte, lighting energy
advisor at Focus on Energy, there has been growing interest in lighting upgrades. 24 Although many
customers may be content with their HID fixtures for the time being, this program also helps them
understand their options for future energy-efficient upgrades.
In June 2008, the City of Palo Alto Utilities (CPAU) rolled out a similar program, Energy Efficiency
Rebates for Your Business, for commercial customers who install energy-efficient fluorescent fixtures
with electronic ballasts and manufacturer-integrated occupancy sensors in garages, hallways, and
bilevel stairways. Bruce Lesch, a representative from CPAU’s utility marketing services, states that the
utility does not have a list of qualifying products yet, but that customers can fill out the rebate form and
show a product specification sheet to be approved for a rebate. 25 The rebate program pays customers
$25 per fixture. When the project is completed, customers must turn in a copy of the invoice and allow
CPAU to inspect the site.
These prescriptive rebate programs for efficient parking lot and garage lighting are more the exception
than the rule. Schulte asserts that garage lighting upgrade incentives are normally based on savings
through a custom program. That’s because replacing an HPS system with fluorescents is not always a
one-for-one fixture swap out, which is typically how prescriptive programs are structured. Custom
lighting incentives for garage lighting fall under Focus on Energy’s custom commercial lighting program,
which has also seen more interest in the past year. Schulte states that the newer options of induction
and LED lighting, in particular, have increased customer interest. She adds that if Energy Star
specifications for LEDs in this application are released, it might allow Focus on Energy to create a new
prescriptive program.
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FOR MORE INFORMATION
General
E Source Lighting Technology Atlas, TALA-05 (2005)
International Association of Lighting Management Companies
Fixtures
Outdoor Parking Lot Lighting, E Source Report, TU-97-6 (1997)
Parking Lot and Area Luminaires, National Lighting Product Information Program, Lighting Research
Center, Rensselaer Polytechnic Institute (2004)
High Hopes for Low-Glare Outdoor Luminaire, California Energy Commission (2006)
Fluorescent Lamps and Ballasts
Ballasts for Full-Size Fluorescent Lamps, E Source Report, TAS-RG-1 (2007)
Lighting Tips and Pointers, E Source Report, ER-02-2 (2002)
Super T8s: Super Lamps, Super Ballasts, E Source Report, ER-03-16 (2003)
Induction Lamps
Long Live Electrodeless Lamps, E Source Report, ER-02-6 (2002)
LEDs
Light-Emitting Diodes, E Source Report, CEMC-RG-1 (2007)
Light Levels
IESNA Lighting Handbook, Illuminating Engineering Society of North America (2000)
Taking Another Look at Lumens in Outdoor Lighting, E Source, Tech News (April 2001)
Light Pollution
Light Pollution, National Lighting Product Information Program, Lighting Research Center, Rensselaer
Polytechnic Institute (2007)
International Dark-Sky Association
Maintenance
E Source Lighting Technology Atlas, TALA-05 (2005), Chapter 12: Lighting Maintenance
Shining a Light on Lighting Maintenance, E Source Customer Direct Pamphlet, MAS-P-10-ESCD (2006)
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GOT A QUESTION ABOUT THIS TECHNOLOGY?
View recently answered member inquiries about lighting on our technology questions page or ask a new
question using the E Source Member Inquiry Service. As a member, you get direct access to our experts
for quick answers to your questions or for timely referrals to other resources.
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NOTES
1
National Lighting Product Information Program (NLPIP), Lighting Research Center, Rensselaer Polytechnic Institute, “Parking
Lot and Area Luminaires” (July 2004), www.lrc.rpi.edu/nlpip/publicationDetails.asp?id=900&type=1.
2
Nancy Clanton and James Benya, “Outdoor Parking Lot Lighting,” E Source Report, TU-97-6 (May 1997).
3
“Demonstration Assessment of Light Emitting Diode (LED) Walkway Lighting,” U.S. Department of Energy (March 2008),
www.netl.doe.gov/ssl/PDFs/Gateway_FAA.pdf.
4
Jim Rogers and Ira Krepchin, “Lighting Tips and Pointers,” E Source Report, ER-02-2 (March 2002).
5
Illuminating Engineering Society of North America (IESNA), “Luminaire Classification System for Outdoor Luminaires,”
Technical Memorandum TM-15-07, www.iesna.org (accessed January 2007).
6
Nancy Clanton, “A Model for Outdoor Lighting Ordinances,” Architectural Lighting (June 1, 2007), www.ebuild.com/articles/
527874.hwx.
7
Mark Rea, ed., IESNA Lighting Handbook, 9th edition (2000).
8
NLPIP [1].
9
Ira Krepchin and Stan Walerczyk, “New Capabilities for High-Bay Metal Halide Technology,” E Source Report, ER-05-3
(January 2005).
10
Ira Krepchin, “The Latest on Lighting,” E Source, Tech News (July 2008).
11
Jeff Waymouth (August 2003), Senior Applications Engineer, Fluorescent Lamps, Osram Sylvania, 978-750-2281,
jeff.waymouth@sylvania.com.
12
Vic Roberts (September 2000), Consultant, High Performance Lighting Systems, 518-399-4952, vic@lighting-research.com.
13
Color Kinetics, “Color Kinetics LED Lifetime,” www.colorkinetics.com/support/whitepapers/LEDLifetime.pdf (accessed August
2007).
14
Jim Rogers and Ira Krepchin [4].
15
NLPIP [1].
16
National Lighting Bureau (NLB), “The NLB Guide to Industrial Lighting” (1992), p. 33, www.nlb.org/
index.cfm?cdid=10352&pid=10225.
17
Nancy Clanton, “Achieving High-Quality Outdoor Lighting that Is Efficient and Sustainable,” web conference, E Source
Technology Assessment Service (September 17, 2008).
18
“Mesopic Street Lighting Demonstration and Evaluation: Final Report,” prepared for Groton Utilities by Peter Morante, LRC,
Rensselaer Polytechnic Institute (January 2008), www.lrc.rpi.edu/researchAreas/pdf/GrotonFinalReport.pdf.
19
Vic Roberts [12].
20
Pacific Northwest National Laboratory, “Compact Fluorescent Lighting in America: Lessons Learned on the Way to Market”
(June 2006), www.pnl.gov/main/publications/external/technical_reports/PNNL-15730.pdf.
21
Nancy Clanton (July 2008), Principal, Clanton Associates, 303-530-7229, nancy@clantonassociates.com; and Proceedings
Outdoor Lighting Symposium (September 2008).
22
Gary Schroeder (February 2002), Energy Services Engineer, City of Fort Collins Utilities, 970-221-6395.
23
Nancy Clanton (January 2001) [21].
24
Liesel Schulte (July 2008), Lighting Energy Advisor, Focus on Energy, 800-762-7077, focusinfo@focusonenergy.com.
25
Bruce Lesch (July 2008), Utility Marketing Services, City of Palo Alto Utilities, 650-329-2244.
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