1. MidAmerican Energy Company
City of Bettendorf, Iowa
Outdoor LED Demonstration and Business Case Report
May 2011
Prepared by: Outsourced Innovation, LLC
721 Arlington Ave., Suite 200
Naperville, IL 60565
630.697.0571
www.outsourced-innovation.com
1
2. Table of Contents
I. Executive Summary
II. Suggested Recommendations
III. Background and Objectives
IV. Iowa Policy on Energy-Efficient Solid State Lighting
V. Solid State Lighting Basics
VI. City of Bettendorf, Iowa, LED Conversion
VII. Philips Lumec’s Capella LED Fixtures
VIII. Illumination Comparisons
IX. Projected Energy Savings
X. Lifecycle Cost Analysis
XI. Conclusions and Final Thoughts
XII. Appendix
2
3. LED Streetlight Demonstration – City of Bettendorf, Iowa
I. Executive Summary
Recent advancements in solid state lighting (SSL) provide new opportunities for achieving
energy efficiency, lowered maintenance costs and higher quality illumination for municipal
street and area lighting.
The efficient use of energy has been an important goal for many initiatives at MidAmerican
Energy. Municipal customers look to their utilities for ways to improve energy efficiency and
implement solutions that create real value and contribute to a better environment.
A collaborative light-emitting diode (LED) demonstration has been established between the city
of Bettendorf and its utility, MidAmerican Energy, to help understand and communicate the
benefits and performance of the technology in real-world applications.
Primary results from the installation of 32 Philips Lumec’s Capella LED luminaires replacing 32
twin-mounted high-pressure sodium acorn fixtures as a one-for-one replacement on 16 poles
along State Street in front of the Quad-Cities Waterfront Convention Center show the
following:
A forecasted 49 percent annual k/Wh savings from Philips Capella fixtures using
MidAmerican’s general municipal light and power rate (rate 45) for the city of
Bettendorf.
The entire 16-pole LED lighting system is projected to save 14,115 kWh each year for an
estimated annual savings of $1,213. The dollar savings is realized from reduced wattage
and reduced usage from the sidewalk-mounted LED luminaires.
Compared to the option of keeping the existing HPS lighting system in place, payback of
>20 years implies the technology is expensive for full-scale retrofit market adoption and
suggests the importance of utility rebates to incentivize municipal technology
demonstrations. A comparison of new LED and HPS lighting systems showed different
results with a payback of 7 years primarily because of the lower maintenance cost
coupled with a longer expected life for LED lighting.
The question of LEDs meeting RP-8-00 Roadway Lighting Standards for a collector road
with respect to light output and uniformity from the Capella LED fixtures on State Street
was inconclusive at this time.
3
4. Methods to predict long-term LED fixture reliability are unclear, implying that strong product
warranties are critical for a municipal application. More time and experience is required to
predict if the Capella LED fixtures will continue to deliver to proposed ENERGY STAR® and
Illuminating Society of North America (IESNA) standards of delivering 70 percent light output
after 50,000 hours. Findings in this report are projections as an LM-79-08 Electrical and
Photometric Report of Solid State Products was not provided for the LED fixtures at this
demonstration site.
II. Suggested Recommendations
It is understood that the light output of LED technology is improving but wide variations exist in
performance by manufacturer. It is common for LED product claims to be exaggerated or
communicated incorrectly by manufacturers (Caliper Round 11, DOE). Although that may not
hold true for this demonstration, measurement and validation is recommended for emerging
SSL technology.
The following recommendations are suggested to ensure the LED luminaires meet performance
criteria:
1. Conduct third-party validation using IESNA measurement protocol and a unified system
of photometry (scotopic/photopic readings), glare assessment or small target visibility
to ensure the LED lighting system meets IESNA RP-8 standards for safe and uniform
roadway lighting on State Street in front of the convention center.
2. Meter a sample of five LED poles to validate if input wattage, power factor and total
harmonic distortion are accurate to performance claims. The tracking of power quality
performance against time, temperature, humidity, weather and environmental swings is
recommended to understand impact from load from an immature technology.
3. Conduct an evaluation of the Philips LED lighting system with Bettendorf residents to
gauge community perceptions and acceptance of the Philips LED Capella fixtures,
especially as it relates to LEDs in front of their homes.
4. Consider a demonstration that compares multiple LED outdoor products. Product
features, energy savings and optics can deliver completely different results depending
on the manufacturer and lighting objectives of the city. An evaluation of the application
of lighting controls and occupancy sensing will further leverage the energy-saving
capabilities and understanding of solid state lighting.
III. Background and Objectives
4
5. Many municipalities are installing LED streetlights. Bettendorf and its utility, MidAmerican
Energy, collaborated on a SSL project to evaluate emerging LED technology as a solution to
potentially save energy and reduce costs.
Bettendorf has a residential population of 33,098 and prides itself on its leadership and use of
new technology that saves energy costs for local citizens. Bettendorf is one of the few cities in
the world to have a fiber optic network available for business use. The installation of SSL
technology was a natural extension of a downtown beautification project at the Quad-Cities
Waterfront Convention Center.
With funding assistance from the American Recovery and Reinvestment Act of 2009 (ARRA) and
MidAmerican Energy, the lighting demonstration included the installation and evaluation of 32
LED fixtures manufactured by Philips-Lumec.
The purpose of the demonstration was to investigate and compare the energy savings, light
output and cost of emerging LED technology as a direct replacement to conventional high-
pressure sodium fixtures that were in place on State Street directly in front of the convention
center.
The main objectives of this study are to answer key questions and concerns related to emerging
LED technology:
1. Can a retrofit replacement of 2-150 watt HPS lamps produce an energy savings following
a replacement with LEDs manufactured by Philips-Lumec?
2. Will photometry following replacement to LEDs meet design guidelines and match or
surpass IESNA RP-8 standards for roadway lighting?
3. What is the actual energy savings for the LED replacement?
4. How will the conversion to LED lighting impact the quality of electric load?
5. What are the visual impact changes for the LED replacement?
6. How does the conversion to LED lighting impact the community perception of safety in
front of the convention center?
7. Does the conversion to LED lighting today make sense economically?
Other primary research suggests the community plays a key role in municipal lighting decisions
and is common practice for lights to be removed if the community is not satisfied (Outdoor
Municipal Lighting Study, Illinois Technology and Sustainability Center – University of Illinois,
Oct 2008). A secondary research project objective might be to gauge community acceptance of
LED lighting in Bettendorf.
IV. Iowa Policy on Energy-Efficient SSL Lighting
5
6. On Sept. 15, 2010, the Iowa Utility Commission adopted a new policy (35.15-3) as pertains to
the replacement of high-pressure sodium lamps with solid state lighting as specified below:
“the new lighting consists of Solid-State Lighting (SSL) luminaries that have an efficacy rating
equal to or greater than 66 lumens per watt according to a Department of Energy (DOE)
Lighting Facts label, testing under the DOE Commercially Available LED Product Evaluation and
Reporting Program (CALiPER), or any other test that follows Illuminating Engineering Society of
North America LM-79-08 test procedures.”.
V. Solid State Lighting Basics
Before discussing the results of this project it might be helpful to define key aspects of exterior
lighting as it pertains to LEDs, using the IESNA definitions for roadway lighting.
Efficacy (lm/watt): The amount of light measured in lumens divided by the total power
consumed (watts)
Light Distribution: The manner in which fixtures distribute light produced by the source; LEDs
are directional light sources that deliver light only where it is needed while minimizing wasted
light and glare.
Horizontal and Vertical Illuminance: The amount of light delivered to horizontal surfaces such
as the ground or the top of a surface, or vertical surfaces such as walls or people, measured in
foot-candles.
Glare: The sensation produced by the luminance within the visual field that is greater than the
luminance to which the eyes are adapted. Disability glare can be classified as annoying,
intolerable, discomfort and could create loss in visual performance.
Color Rendering Index (CRI): A measurement for how accurately a lighting source renders
colors. CRI for LEDs can typically range from 60-75. A CRI of 100 is considered to be excellent.
Correlated Color Temperature (CCT): The appearance of a light source, measured in Kelvin.
CCT can have a strong impact on the appearance of the street being illuminated. HPS lamps
have CCT of ~2100K and are very orange in appearance. Many outdoor LED products are bluish
white and tend to have a Kelvin rating of 5000-6000K.
Lumen Depreciation: The decrease in light output that occurs as a lamp is operated. Lumen
depreciation in LEDs varies depending on package and system design. LEDs continue to operate
even after their light output has decreased to very low levels. This becomes the important
factor in determining the effective useful life of the LED.
Lumen Maintenance: The opposite of lumen depreciation, lumen maintenance is how well a
light source maintains light output over time. Good quality LEDs should deliver 70 percent of
initial light output after 50,000 hours or more of use.
6
7. LM-79-08: A third party test report of Electrical and Photometric Measurements of SSL Products
that publishes photometrics, color and electrical power as measured in controlled
environments. Reputable LED vendors will show this report.
LM-80: An approved method for measuring lumen maintenance of LED light sources and
describes how lumen maintenance testing should be conducted for LEDs. Reputable LED
vendors will show this report.
BUG Rating: A new cutoff classification for outdoor LEDs that represents B-backlight,U-uplight
and G-glare. BUG ratings limit the lamp lumens to values that are appropriate for lighting zones.
Unified System of Photometry: A proposed new measurement that combines photopic light
levels (spectral sensitivity of the eye during the daytime) and scotopic light levels (spectral
sensitivity of the eye at nighttime) to achieve optimal light level and maximum energy efficiency
for outdoor lighting.
Cost of Ownership: LED lighting sytems have advantages and disadvantages. When selecting
fixtures it is important to evaluate beyond first cost and consider long-term energy,
maintenance and environmental savings.
VI. City of Bettendorf, Iowa, LED Conversion
The focus of this project was to replace 32 HPS street fixtures with 32 LED luminaires provided
by Philip Lumec. The Capella LED fixtures were chosen for the sidewalk features 30 LED
packages and a Type III, short distribution (model # CPLS-MS51863A). The Capella LED fixtures
chosen for the street features 98 LED packages, type III distribution (model #CPLMLMS51863A).
Illustration I show the existing HPS fixtures mounted in State Street in front of the convention
center. These twin-mounted acorn HPS lamps produced 150 watts each (not including ballast),
were mounted at 25 feet with 160-180 feet between poles and a Type V light distribution
pattern.
7
8. Illustration 1 – Conventional HPS Fixtures Prior to Conversion to LED
The Illumination Engineering Society (IES) writes many of the industry standard specifications
for fixtures. The IES has designated several standard types based on their light distribution
patterns for the basic types of conventional luminaires. The LEDs were designed as a type III
distribution rather than a type V from conventional HPS fixtures to show directionality inherent
in LED lighting.
The area of required illumination from each pole measured approximately 11,040 square feet
with 69 feet between four lanes of traffic and 2-10 foot sidewalks on both sides of the street.
8
9. Instructions for LED conversion were to design to meet or exceed IESNA RP-8 specifications for
roadway lighting. The State Street roadway classification in front of the Quad-Cities Waterfront
Convention center was rated as a Collector road with medium pedestrian conflict and pavement
classification of R2/R3.
New poles were installed and 32 Lumec-Capella fixtures were mounted in May, 2010. Foot-
candle measurements were taken by NRG Sales using a hand-held meter. See Appendix A.
VII. Philips Lumec’s Capella LED Fixtures
Figure 1 – Capella Fixture Temperature Rendering (24.9C to 97.72 C)
Heat is a primary enemy of LEDs. Failure rates can double when the junction temperature
increases by 10˚-20C˚ (Reliability and Lifetime of LEDs, Osram Opto 2011). Fixtures engineered
with good thermal design are essential to achieving long hours of service life.
Figure 1 shows a temperature rendering of the Capella fixture, the amount of heat they
produce, manage and dissipate within the fixture.
New poles were part of the project redesign as shown in Figures 2, 3 and 4 below.
9
10. Figure 2 – Pole Showing Sidewalk Mount 12 feet (left); Street Mount 25 feet (right)
Figure 3 - Sidewalk Mid-Pole LED – 68 watts Figure 4 - Street LED 147 watts
10
11. Illustration 2 – LED Capella Fixtures
The new LED mounting design (shown in Illustration 2) used a single head, 68-watt LED fixture
mounted at 12 feet to illuminate the sidewalk and a single head, 148-watt LED fixture mounted
at 25 feet to illuminate the street.
The main LED product attributes for the Lumec Capella fixtures compared to the conventional
HPS lighting system are outlined in Table 1.
Since the 150 watt HPS fixtures on each pole used ballasts, they actually consume about
380 watts each. The wattage for the LED fixtures on each pole, including power supply,
is projected to consume 215 watts, representing a savings of over 44 percent.
The HPS lamps are rated for 24,000 hours. The LEDs are rated for 70,000 hours.
The CCT and CRI for are vastly improved with the LEDs, going from 2100K and 22 CRI
with HPS to 4331K and 67 CRI from LED.
Proposed ENERGY STAR standards (ENERGY STAR Program Requirements for SSL
Luminaires - July 2009) for outdoor pole-mounted area and roadway luminaries appear
to have been met with the Capella fixtures at between 62 and 80 lm/watt, 99.5 percent
power factor and total harmonic distortion published at <20 percent.
There was no LM-79 report submitted for the LED fixtures and lamps are not UL tested
at the time of this report.
11
12. Table 1 –Philip Lumec Capella LED versus Conventional HPS
Conventional
LED Street Side- LED Sidewalk – Twin Acorn
Capella Luminaire Capella, Mid-Pole Luminaire 150 watt HPS
Wattage 147 watts 68 watts 380 watts
Lumens 11,780 4250 32,000
Lm/watt 80.13 62.5 84.21
Kelvin 4331K 4331K 2100K
Color Rendering Index 67 67 22
Drive Current 428mA 600mA -
# of LEDs 98 30 -
Rated Life 70,000 hrs 70,000 hrs 24,000
BUG Rating B2 U1 G2 B1 U1 G1 No cutoff
ROHS Compliant yes yes no
LM 79 and LM 80 Reports LM79: no LM79: no
(yes/no) LM80: yes LM80: yes
Active or Passive Cooling Passive Passive -
Maximum Operating -40˚F - 130˚F (40C- 55C) -40˚F - 130˚F (40C- 55C)
Temperature
Can you provide an IES file? Yes (scaled) Yes (scaled)
IP Rating IP-66 IP-66
UL Tested? Not yet but will be Not yet but will be
Power Factor 99.4% 99.5%
THD <20% <20%
Voltage 120 V 120V 120V
Warranty 5 years –full/limited? 5 years – full/limited? 1-2 years
Light Distribution Type III Type III, short Type V
Hours of Operation 13 hours 9 hours 13 hours
VIII. Illumination Comparisons
The central question to the project was to understand whether the LEDs installed on State
Street achieved IESNA RP-8 standards for light output and uniformity required for safe roadway
lighting as outlined below in Table 2.
Road Classification Pedestrian Conflict Area Pavement Classification Uniformity
Ratio (Ave/Min)
Collector Medium R2&R3 (.9 foot-candles) 4.0:1
Table 2 – IESNA Lighting Handbook – Light Level Recommendations for Roadway Lighting
A light rendering (Illustration 3) was created using a vendor-provided IES file and AGI32
software to show anticipated light distribution at ground level from the Capella fixtures on
State Street.
12
13. Illustration 3 –Forecasted LED Light Rendering on State Street
The combined IES files illustrate projected light renderings from a single pole with 25 foot and
12 foot mounting heights with each fixture oriented in opposite directions and staggered poles
along a four-lane street (Illustration 4). Three-dimensional foot-candle projections are
meaningful by illustrating the role of optics in minimizing glare or hot spots to create uniform
lighting on the street.
Projections like these are important to answering whether light intensity of the Capella LED
fixtures creates sufficient horizontal illuminance and vertical luminance without creating
disability glare to the drive.
13
14. Illustration 4 – Projected Foot-Candle Distribution from 1 Pole with Capella LED
Fixtures (no LLF)
Good measurement and validation protocol using a unified system of photometry will help
answer whether the Capella LED fixtures distributed light sufficiently to meet IESNA RP-8
standards as outlined earlier in Table 2.
Table 3 shows estimated and measured light levels produced from the HPS and LED fixtures.
Initial foot-candle results using a hand-held light meter are promising as baseline average
illuminance was measured at .911 foot-candles for HPS and 1.43 foot-candles from LEDs. These
findings suggest that LED fixtures resulted in slightly higher overall photopic illumination on the
street compared to HPS. There was insufficient data to assess if a uniformity ratio of 4:1 was
met.
Table 3: Projected and Measured Illumination from Capella LED Fixtures (foot-candles)
Av IL Av IL Max IL Min IL Ave/Min Max/Min Uniformity Ratio (X:1)
Projected Measured* Projected Projected Projected Projected Projected
Sidewalk 99 N/A 3.96 0.07 14.14 56.57 N/A
LED Street 1.11 1.43* 3.49 0.15 7.40 23.27 N/A
HPS Street .911*
*Represents 10 light readings with hand-held meter
14
15. A word of caution, these measurements were taken using a hand-held light meter. For
accurate measurement and validation of LED lighting systems it is common practice to use a
vendor-neutral engineering firm using NIST approved, scientific-grade light meters, an 80-90
point grid system with a sufficient number of horizontal illumination and vertical illumination
measurements at about 4 feet above grade with consideration for surrounding ambient light.
This would include both photopic and scotopic light measurements as both are relevant when
evaluating new outdoor LED street lighting systems.
The Rensselaer Lighting Research Center recommends using a new unified system of
photometry as a better way to characterize seeing under nighttime lighting (Outdoor Lighting:
Visual Efficacy, January 2009). This means applying an S/P ratio to baseline photopic luminance
to determine optimal light output for LEDs.
IX. Projected Energy Savings
Based on the spec sheets provided by Philips Lumec it is forecast that this LED demonstration
will deliver an estimated 49 percent energy savings. There was no LM-79 report provided by the
manufacturer so these estimates are projected without validation.
Assuming the LED street lights operate at 4,745 hours annually and the LED sidewalk lights at
3,285 hours, the annual energy savings that could be realized are shown in Table 4.
Location Number of Fixtures Original Fixtures LED Fixtures Estimated Savings
Watts kWh Watts kWh Annual kWh %
HPS Street 32 380 28850
Street LED 16 147 11,160
Sidewalk LED 16 68 3574
Total 14,734 49%
Table 4 – Annual Energy Savings
Installing power meters on a sample of >five fixtures will validate input wattage and other
important power quality attributes of solid state lighting. This includes measuring power factor
and total harmonic distortion, input wattage in the on and off state, any potential voltage
swings, impact on load from temperature changes and other power quality risks associated
with a scalable deployment of outdoor electronic lighting.
Based on a 160 foot distance between each pole, the estimated reduction in lighting power
density resulting from the conversion from HPS to LEDs on State Street went from 0.03 w/ft²
watts to 0.019 w/ft².
X. Lifecycle Cost Analysis
15
16. While technical performance in street settings is critical to technology adoption, potential
purchasers likely will look at financial performance first.
In conversion applications, product lifetime and reliability are critical contributors to a financial
analysis. This is especially true when payback is measured in years, where long warranties are a
business necessity and where reduced maintenance costs form a significant portion of the
return on investment. Also, since the LEDs are expected to last more than 3-5 times longer
than conventional HPS lamps, lighting maintenance costs should be considerably lower.
The key financial metrics of payback period are discussed below to help understand if LED
technology today makes financial sense for Bettendorf. The economic analysis captures two
comparisons: 1) the city decides to invest in LED streetlighting or keep the existing lighting in
place, and 2) the city decides between a new LED lighting system or a new HPS system.
The lifecycle analysis will take into account the assumptions indicated in Table 5.
Existing New System – HPS New System - LED All
System - HPS
Energy Savings HPS HPS-1 HPS-2 LED-1 LED-2
380 190 120 147 68
Wattage (Watts)
Hours of Operation
Daily 13 13 9 13 9
Annual 4,745 4,745 3,285 4,745 3,285
Annual Electricity Usage 1803 902 394 698 223
(kWhr)
Electricity Cost (cts/kWhr)
Summer 9.906
Winter 7.936
Maintenance Savings
Rated Life (Hrs) 24,000 24,000 24,000 70,000 70,000
Years to Replacement 5 5 5 15 21
Warranty (Yrs) 1-2 1-2 1-2 5 5
Maintenance Cost
Full Labor Rate ($/hr) 125 125 125 125 125
Maintenance Time (hrs) 1 1 1 1 1
Cost to Replace $345 $705 $484 $818 $598
Financial
Time Frame (yrs) 20
Electricity Escalation (%/yr) 2.0%
Discount Rate (%) 6.5%
Table 5 – Lifecycle Cost Assumptions
The applicable rate for this streetlighting application in Bettendorf is MidAmerican Energy’s
Rate 45, the general municipal streetlighting service rate. The summer rate is 9.906 cents per
kWhr and the winter rate is 7.936 cents per kWhr. The average rate over the full year is 8.6
16
17. cents per kWhr. At this time, MidAmerican Energy only offers a metered rate for LED
streetlighting. The $5 monthly meter charge applies to all metered consumption (typically many
street and traffic lights) and is considered a negligible component for this analysis.
The LED fixtures are projected to save 882 kWh each year from each pole for an annual savings
of $76. The entire 16-pole LED lighting system is projected to save 14,115 kWh each year for an
annual savings of $1,213. Compared to the current HPS lighting in place, a new LED system will
use 49 percent less energy and the new, efficient HPS system will use 28 percent less energy.
The maintenance cost savings are expected to be an important component of the value of LED
lighting. With a 70,000 hours lifetime, LED lights are expected to last about 3 times longer than
HPS. However, in order for these savings to be fully realized, LED equipment costs will need to
come down. The savings are based on the assumption that the LED systems are reliable in the
field, but more experience is needed to verify this.
When the investment in new LED lighting is compared to keeping the existing system in place,
the energy savings did not payback the installed cost of the LED lighting within the 20-year
horizon of the analysis. The installed cost of the LED lights would need to be around $2,000 for
the project to pay off the additional capital cost for the LED lighting. Lower lighting costs would
also reduce replacement cost and improve the life-cycle cost. An additional price reduction
would be needed for scalable deployment of LED lighting with a payback under 10 years. These
calculations also illustrate the importance of utility rebates to incentivize deployment of
outdoor solid state lighting products.
A head-to-head comparison of new HPS and LED lighting systems produced a different result. In
this case, mainly because of the maintenance cost savings, the LED system had a 7-year
payback.
LED technology is reported as following Haitz Law which suggests that light output increases by
a factor of 20 and costs decrease by a factor of 10 every 10 years (DOE SSL Projections). This
has financial implications for projected future capital investments and perhaps will help to
make solid state lighting technology a more realistic business decision with higher costs being
less of a market barrier in the coming years.
XI. Conclusions and Final Thoughts
The primary conclusion from this demonstration is that LED lighting systems, although
expensive, could deliver a 49 percent energy savings to Bettendorf compared to existing HPS
streetlights while achieving higher light levels and better quality illumination in front of the
Quad-Cities Waterfront Center.
It is uncertain whether the Philips Lumec products met IESNA RP-8 Standards for safe roadway
lighting on State Street. Further, sub-metering a sample of LED fixtures will help validate input
wattage and power quality factors to understand the corresponding wattage reduction that will
be realized from a large scale replacement of HPS with LEDs.
17
18. Anecdotally, impressions of the LED lighting have been extremely favorable suggesting that
continued deployment of LED lighting could be acceptable to Bettendorf residents.
Emerging technology demonstrations such as this can provide valuable insights regarding
emerging solid state lighting technology. Lessons learned from the project include the
following:
Laboratory testing suggests that the useful life of LED fixtures should reach a minimum
of 50,000 hours. There is insufficient experience with LEDs to achieve those claims as
more real-world demonstrations are required to back reliability claims. The DOE is
comfortable with useful life claims of 35,000 hours but not beyond that. Strong product
warranties are essential to mitigate the risk of early system failure.
The DOE continues to report a wide variability in product performance and performance
claims that are untrue to specs (Caliper 11). This necessitates the importance of your
own product demonstrations with solid measurement and validation procedures over
time and evaluating multiple products before making a scalable purchase decision.
MidAmerican Energy will offer energy efficiency incentives for qualified LED exterior
fixtures beginning March 2011. Please go to www.midamericanenergy.com/ee for more
details.
18
19. XII. Appendix
Foot-Candle (photopic) Readings of LED Compared to HPS (provided by NRG Sales)
19
