ENERGY UPDATE: SHARED SOLAR PROGRAMS FOR FACILITIES THAT CAN’T
HOST ON-SITE PHOTOVOLTAICS COULD REPRESENT 32-49% OF THE
DISTRIBUTED PHOTOVOLTAIC MARKET BY 2020, ACCORDING TO THE
NATIONAL RENEWABLE ENERGY LABORATORY.
LEDs for Parking Garage Lighting
By Eric Woodroof and Jeff Pinyot
➙Formerly dominated by high- pressure sodium (HPS), metal
halide (MH), fluorescents and
induction lamps, parking garage light-
ing is now a common application for
LEDs. Their benefits often include en-
ergy efficiency and whiter light. On the
other hand, LEDs have been known to
have glare and poor light distribution.
When evaluating LEDs for your garage, consider the following factors.
Safety and Security
Key requirements for parking garages
include safety and security. An effective parking garage lighting fixture
should provide excellent uplighting to
eliminate “cave effect.” Fixtures should
have good sidelighting to illuminate
columns and signage. Standards specify
no more than a 10:1 variance in lighting
from a max/min ratio. In other words,
no garage section can have more than 10
times the minimum lighting level of any
other point in a garage.
The garage also should have a lighting
level of at least 5 footcandles for proper
Traditionally mounted at just 8 feet
high, parking garage lighting is particularly challenging for directional lighting
like LEDs. The glare of many early
LED fixtures was dangerous, distracting and a huge potential legal liability
if a mishap occurred due to temporary
impairment of a person’s vision. LED
suppliers have responded with low or
no glare designs. Fixtures with double
refraction/reflection spread their light
effectively and have revolutionized
It is also critical to specify that LEDs
be shielded with more than a directional
TIR (total internal reflection) optic. Virtually all manufacturers of LED parking
lighting have shielded options. You must
insist on them.
In terms of efficiency, you should not
consider an LED fixture that doesn’t
have an effective output of at least
100 lumens per watt. Also, you should
consider fixture-mounted motion
and photocell sensors. Coupled with
this technology are parking guidance
ENERGY SAVINGS for parking garages can be achieved with an LED retrofit, but be sure to choose
fixtures with good uplighting and sidelighting to avoid common pitfalls.
continued on page 11
Do the Math on Savings
A typical garage includes about 300 lighting fixtures. A high percentage of existing garages use 150-watt
HPS (with characteristic yellow light) or a 175-watt MH (white light). Let’s consider the economics of the
very popular 175-watt MH.
A 175-watt MH consumes about 208 watts (including ballast).
300 fixtures x 208 watts = 62,400 watts or 62.4 k W.
A new LED fixture can replace the 175-watt MH and draw only 45 watts.
300 fixtures x 45 watts = 13,500 watts or 13. 5 k W.
The savings in total k W usage is 62.4 k W – 13. 5 k W = 48. 9 k W.
Most parking garage lighting fixtures operate 24 hours per day. Assume a national average of utility
costs to be 11 cents/k Wh.
Annual energy savings by going to the LED:
48. 9 k W x 8,760 hours per year (24/7/365) x 11 cents/k Wh = $47,120.
Assume annual maintenance savings by using the new LED over the MH to equate to about 1/4 of the
$47,120 energy savings + ($47,120 x . 25) maintenance savings = $58,900 total savings.
A typical installed replacement cost using new low or no glare fixtures is approximately $475 per fixture.
Assume a national average of a $100 utility rebate per fixture results in the total installed fixture cost to be
Installed price of $375 x 300 fixtures = $112,500.
The simple payback = $112,500/$58,900 = 1.91 years.