1. August 2010 –
January 2012
Hoosier Energy – Energy-Efficient LED Lighting for High-Bay
Cold Storage Warehouse Applications
Prepared by Outsourced Innovation, LLC
The business information related to the findings in this report is confidential to Hoosier Energy and
Interstate Warehousing. Results from this evaluation are specific to this location and application.
These results, analyses, tests, or findings of Hoosier Energy or its Member system REMCs will not
be used as endorsements of the product or for advertising purposes without the express written
permission of Hoosier Energy or the Member system REMC. Any testing or analysis performed by
August 2010 – January 2012
Hoosier Energy or its Members system REMCs is done solely for internal purposes.
2. Table of Contents
Page
Introduction & Background 3
Executive Summary 3
Research Implications & Recommendations 4
Research Methodology 4
Illumination Measurements 6
Energy Comparisons & Power Quality 7
Energy Savings & Financial Analysis 8
Customer & Employee Feedback 10
Conclusions 11
Appendix A – Digital Lighting Specification Sheet 12
Appendix B– Photometric Data Points at 6,000 Hrs. 14
2
3. Introduction & Background
Hoosier Energy is evaluating an intelligent solid state lighting (SSL) system as an emerging technology
solution to reduce on-peak demand. New SSL systems are designed to deliver significant energy savings
relative to legacy light sources by leveraging adaptive lighting technologies (dimming and occupancy
sensing) inherent in light emitting diodes (LEDs).
Industrial high-bay SSL lighting systems are in their early market entry with little real-world application
experience. Interstate Warehouse opened a new state-of-the-art public freezer/refrigeration
warehouse in Franklin, IN and was identified as an ideal site to conduct an assessment of a SSL system
manufactured by Digital Lumens™. Digital Lumens engineered an intelligent LED lighting system with
the additional feature of controls to leverage efficiency gains compared to the T5 fluorescent lighting
system they replaced.
A core customer value of LEDs is energy and maintenance savings but it is anticipated that smart sensors
engineered into these LEDs will limit “on time.” This will produce an even greater energy savings as
fixtures will be programmed to cycle “off” after 2 minutes of employees leaving the work area compared
to a 15-minute occupancy sensing in fluorescent technology.
This evaluation included a direct comparison of LEDs against T5s on light output, energy savings and
load reduction. Also, unlike fluorescent lighting, LEDs claim to perform well in cold environments making
the Interstate facility an ideal site location to evaluate light performance in a freezer environment.
The question of reliability will be addresses and whether LED light levels will hold out over time. Lastly,
the project will gauge customer feedback and employee acceptance of LEDs to determine if employees
prefer working under LED lighting.
Executive Summary
This lighting project was established to understand the advantages and risks of emerging intelligent SSL
lighting technologies.
It is projected that the installation of an intelligent lighting system manufactured by Digital Lumens
should result in a 42% reduction in peak demand compared to the T5s lighting system, mostly due to
shorter occupancy sensing capabilities from LEDs. LED Input wattage was validated as being 10% higher
than claimed by the Digital Lumens product spec sheet with power factor and total harmonic distortion
slightly lower than EnergyStar® rated specifications. Site metering validated the installation of 172 LED
fixtures will create 17.391 total kW.
Compared to T5s, having fewer LED fixtures at lower wattages an estimated energy usage reduction of
70% is projected. Metering the T5 fixtures will support this forecast. With a projected rated power
capacity reduction and estimated total energy usage reduction, LEDs appear to provide a good solution
to reduce electric load more efficiently than T5 lighting solutions, even at the higher reported wattages
claimed by the LED manufacturer.
3
4. Long-term fixture reliability is unclear and an important caveat with SSL systems. The measured 2
footcandle drop in average illumination after 6,000 hours raises questions about Digital Lumens
meeting performance claims of a 50,000 hour service life, especially when measured LED light levels are
already below the 15 foot threshold expected at the start of the project.
An investment in an intelligent lighting system is more costly upfront. This project includes a longer
payback (3.5 years) compared to T5s but a 35% Internal Rate of Return (IRR) and 20-year net present
value cost positive result suggests that LEDs could be a good long-term capital investment as long as
product reliability is assured.
Research Implications and Recommendations
These results show the progress in SSL systems for commercial high-bay applications, both in terms of
improved light levels and energy savings. Although more costly upfront compared to other efficient
lighting systems, LEDs can provide a solution to reduce peak demand for Hoosier Energy and the
customers they serve, especially in the near future as costs appear to be dropping about 10-20%
annually. The challenge today is that LED fixtures installed today are quickly outdated with new versions
having higher light output and new capabilities.
The following recommendations are provided for consideration.
1. Install a Dent meter on a sample of T5s fixtures so more exact energy performance comparisons
can be made at Interstate. Without measurements from the T5s, we are missing a critical piece
of input data to isolate early shut-off savings compared to LED.
2. The relatively large percentage drop in measured light output after 6,000 hours from the Digital
Lumens product should be addressed in discussions with the company. SSL is still immature and
evolving technology with long-term performance claims today that are extrapolations rather
than more understood and assured with fluorescent alternatives.
3. Continue to provide good legal verbiage in product warranties. This should include protection on
the product, driver, color shift and droop. Five-year full product and driver warranties are more
common and we are beginning to see 7-year warranties on other high-bay products.
4. Ask LED vendors to provide TM-21 data that extrapolates long-service life for LED fixtures tested
using LM-80 test protocol. This new standard provides additional assurance of long service life.
5. Consider comparing the performance of more than one solid state lighting system in future
product demonstrations. There appears to be more industrial high-bay products market ready
for evaluation, especially as pertains to wireless controls and integration with a facility’s energy
management system.
Research Methodology
The primary research hypothesis was to demonstrate that matched or better illumination can be
achieved from LEDs with a goal of achieving at least 15-20 horizontal foot candles at floor level.
4
5. Mounting height was 42 feet with 25 foot spacing between fixtures at both the LED and the T5 facilities.
Lighting was established on a 3-phase circuit panel at 277 volts with 33 fixtures on each breaker.
The cold-storage warehouse occupies 120,000 square feet of space with each warehouse having
between 172-186 light fixtures and occupancy sensing set at between 40-45%. The fluorescent lighting
was set at 40% occupancy with a 15-minute time delay, whereas the LED at 45% occupancy with a 2-
minute time delay. The schematic below in Figure 1 shows the configuration of LEDs with areas
highlighted in green as fixtures programmed as always “on” and at 25% dimming so the facility is never
completely dark.
Figure 1 – Schematic of Installed Digital Lumens Fixture
The lighting specifications indicated on the third-party laboratory test reports (LM-79) provided by the
manufacturer indicated the LED lighting system should deliver a 43% energy savings drawing 166 watts
compared to a 5-lamp T-5 fluorescent lighting system with an estimated power draw of ~230 watts. The
power quality features of this lighting will be validated using Dent Elite Pro power meters and will
5
6. include a measurement and validation of input wattage, power factor and harmonic distortion for a
sample of 61 LED fixtures.
LED fixtures were installed the week of August 16, 2010 and left on 24/7 for 3 weeks to season LED
fixtures prior to taking illumination measurements. An identical 4’ by 3’ light grid was established in a
12”2’ aisle within the warehouse, with 66 light measurement points take under a sample of 5 fixtures
within both the T5 and LED facilities.
Illumination Measurements
Illumination measurements according to Illuminating Engineering Society of North America (IESNA)
research protocol were taken at the T5 and LED facilities by a LEED certified engineer on December 6,
2010. Temperature and humidity was measured at 13 degrees and 31% humidity in the T5 facility and
22 degrees and 39% humidity in the LED facility.
Average Illumination measurements taken 3 months after the lights were installed and shown in Table 1
below validates that LED light output surpassed T5 light output by 45% or as much as 5 footcandles
photopically, and 13 footcandles scotopically. The facility has achieved a higher maximum illumination
with LEDs with almost equal light uniformity which means the light is disbursed equally throughout the
warehouse and without hot spots or unnecessary glare.
Table 1: 1,000 Hour and 6,000 Illumination Measurement Comparisons
These initial results demonstrate the potential for the Digital Lumens product to deliver enhanced
illumination using fewer fixtures more efficiently. The data suggests better quality illumination using
about 80% fewer lumens compared to T5’s in the adjacent warehouse, and shows the directional
characteristics inherent in LED technology.
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7. Because LED drivers are the weakest link in SSL technology, key to reliability and long service life is
monitoring an LED lighting system over time. LED Light levels are expected will hold stable through
50,000 hours of use and through daily cycling on/off.
A surprising finding showed a 2 – 4 foot candle decrease in light levels in 1 year (noted above in red).
This falls below the 15-20 footcandle threshold that was established for LEDs at the beginning of the
project. At a drive current of 900 mA, these reported LED light levels are still higher than new T5s but
raises questions about long-term lumen maintenance claims of 70% light output after 50,000 hours
which is an important guiding standard with this technology.
Energy Consumption and Power Quality Measurements
The demonstration included metering 35% of the total LED fixture installed to build a load profile from
the intelligent lighting system. A Dent Elite Pro utility-grade power meter was installed by site personnel
at Interstate on January, 2011 to monitor and report input wattage, power factor, total harmonic
distortion and energy consumption from the conversion to an intelligent LED lighting system.
Power quality measurements were taken from a sample of 61 LED lamps installed within 6 rows,
monitored on a 3-phase circuit having 3 channels (1 channel per phase), with initial measurements
taken in 15-minute time intervals for 10 days to determine consumption (k/Wh) and changed to 15-
second intervals for estimate demand (kW) and/or address coincidence peak. Table 2 shows the
validated input wattage and power quality characteristics of the Digital Lumens product.
Table 2 – Validation of Input Wattage and Power Quality from Digital Lumens Product
# of Input Wattage per Power ITHD (manual reading w/# of
LEDs fixture Factor fixtures “on”)
Channel 1 20 180.00 .873919 28.0 (13 fixtures)
Channel 2 21 182.857 .87393 27.9 (14 fixtures)
Channel 3 20 180.00 .886309 27.7 (11 fixtures)
Digital Lumens
Average 61 180.983 .877985 27.867
The Dent meter validated important characteristics that are not yet understood with LED lighting
(wattage change from cold temperature, voltage swings, harmonics, scalable deployment of electronic
lighting, etc.). This data suggests that the Digital Lumen fixture has an input wattage of 181 watts rather
than 166 watts made on product specification sheet. This is not unlike other field studies that suggest
higher LED wattages in colder temperatures.1 This implies a 21% energy savings compared to the energy
savings from T5s.
1
Field trials collect performance data for LED outdoor area lighting; LED Magazine, March 2011
7
8. Over two-thousand data files were obtained to create a typical load profile reflecting the use of LEDs
and advanced lighting controls during normal weekday business hours. This data was extrapolated to
make energy forecasts for the entire section of the warehouse installed with LEDs as shown in Table 3.
Results from 61 metered LED fixtures in this demonstration, with 20% (13 fixtures) programmed as “on”
created a reasonably accurate forecast of the Annual Energy Use and Peak Demand for the 172 Digital
Lumens fixtures installed at the demonstration site.
Table 3 – Forecast Annual Energy Use and Peak Demand for Digital Lumens Product
# of Digital Peak k/W per Ave kWh/fixture Total kW Annual kWh
Lumens Fixtures fixture
172 0.101110656 7.73192623 17.39103 69,154.3482
There is no measured peak demand or energy consumption data files for the T5s. Without metered
data files it is difficult to make apples-to-apples comparisons to LED. However, there is enough general
understanding of light on/off activity on the LEDs that somewhat reasonable projections can be
concluded for the T5s at Interstate.
A measured peak at 56% of maximum power capacity for LEDs is baseline and allows for component
breakdown. The equivalent for the T5s is assumed to be 100% and is no doubt high, but without
measurements we are missing the critical piece of input data to isolate early shut off savings so these
efficiency comparisons are conservative and will more likely be even more favorable to T5s if we had
that data to confirm as well.
Energy Savings and Financial Analysis – Lifecycle Costs
Installation, energy and maintenance assumptions were made to support the financial and lifecycle cost
analysis as shown in Tables 4 and 5.
1. Installation Cost LED T5
Full Labor Rate ($/hr) $50 $50
Installation Time (hrs) $1 $1
Additional Material Cost $25 $25
Fixture Cost $700 $465
Total Installed Cost $750 $515
2. Energy Cost LED T5
2A. Energy Consumption
Total Number of Fixtures 172 186
Number of Fixtures (Minimum Op) 42 42
Wattage (Watts) 180 290 Capacity Reduction 42.6%
Maximum Capacity (kW) 31.0 53.9
Peak Demand (kW) 17.4 30.3
Hours of Operation (Full) 7,488 7,488
Hours of Operation (Minimum Op) 1272 1272
Dimming Ratio (Minimum Op) 25% 25%
Electricity Usage (Meas) (kWhr) 69154
Electricity Usage (Calc) (kWhr) 132620 230742 Total Energy Usage Reduction 70.0%
Equivalent Load Factor 52.1%
8
9. 2B. Energy Rate LED T5
Electricity Cost (cts/kWhr)
Summer 0.0471 0.0471
Winter 0.0471 0.0471
Demand Charge ($/kW) 10.56 10.56
KVA Charge ($/kVa) 12.56 12.56
Energy Cost $3,257.17 $8,619.42
Demand Cost $183.64 $253.75
Total Energy Cost $5,460.83 $11,664.40
3. Maintenance Cost LED T5
3A. Product Lifetime
Rated Life (Hrs) 50,000 25,000
Years to Replacement 7 3
Warranty (Yrs)
3B. Lighting Maintenance
Full Labor Rate ($/hr) $50 $50
Maintenance Time (hrs) 0.50 0.50
Maintenance Material Cost $188 $50
Cost to Replace-Eqpt $213 $129
3C. Driver/Ballast Maintenance
Driver Replace Cost $200 $100
Driver Replace Frequency (yrs) 5 5
Maintenance Time (hrs) 0.25 0.25
Total Cost to Replace Drivers $213 $113
Table 4 – Assumptions for Lifecycle Analysis
The financial assumptions shown in Table 5 were used to project the investment return in a solid state
lighting system.
4. Financial Parameters
Time Frame (yrs) 20
Inflation Rate 3%
Electricity Escalation (%/yr) 3%
Discount Rate (%) 5%
Real Discount Rate (%) 2%
Cost of Capital N/A
Hurdle Rate 10%
Table 5 – Financial Assumptions
The investment was calculated using the time value of money and over a 20-year life as shown in Table 6
and takes into consideration the time value of money.
9
10. LED T5
Year Labor & Material Energy Nominal value Present value Labor & Material Energy Nominal value Present value
2011 $129,000 $5,461 $134,461 $134,461 $95,790 $14,707 $110,497 $110,497 $23,964 $23,964 $23,964
2012 $0 $5,625 $5,625 $5,357 $0 $15,149 $15,149 $14,427 -$9,524 -$9,070 $14,440
2013 $0 $5,793 $5,793 $5,255 $0 $15,603 $15,603 $14,152 -$9,810 -$8,898 $4,630
2014 $0 $5,967 $5,967 $5,155 $141 $16,071 $16,212 $14,004 -$10,245 -$8,850 -$5,614
2015 $0 $6,146 $6,146 $5,057 $0 $16,553 $16,553 $13,618 -$10,407 -$8,562 -$16,021
2016 $246 $6,331 $6,577 $5,153 $130 $17,050 $17,180 $13,461 -$10,603 -$8,308 -$26,625
2017 $261 $6,521 $6,782 $5,061 $154 $17,561 $17,715 $13,219 -$10,933 -$8,158
2018 $0 $6,716 $6,716 $4,773 $0 $18,088 $18,088 $12,855 -$11,372 -$8,082
2019 $0 $6,918 $6,918 $4,682 $0 $18,631 $18,631 $12,610 -$11,713 -$7,928
2020 $0 $7,125 $7,125 $4,593 $168 $19,190 $19,358 $12,478 -$12,233 -$7,885
2021 $286 $7,339 $7,624 $4,681 $151 $19,765 $19,917 $12,227 -$12,292 -$7,546
2022 $0 $7,559 $7,559 $4,420 $0 $20,358 $20,358 $11,903 -$12,799 -$7,483
2023 $312 $7,786 $8,098 $4,509 $184 $20,969 $21,153 $11,779 -$13,055 -$7,269
2024 $0 $8,019 $8,019 $4,253 $0 $21,598 $21,598 $11,454 -$13,579 -$7,201
2025 $0 $8,260 $8,260 $4,172 $0 $22,246 $22,246 $11,236 -$13,986 -$7,064
2026 $331 $8,508 $8,839 $4,252 $376 $22,913 $23,289 $11,203 -$14,450 -$6,951
2027 $0 $8,763 $8,763 $4,014 $0 $23,601 $23,601 $10,812 -$14,838 -$6,797
2028 $0 $9,026 $9,026 $3,938 $0 $24,309 $24,309 $10,606 -$15,283 -$6,668
2029 $373 $9,297 $9,669 $4,018 $219 $25,038 $25,257 $10,495 -$15,588 -$6,477
2030 $0 $9,576 $9,576 $3,789 $0 $25,789 $25,789 $10,206 -$16,214 -$6,416
$130,809 $146,735 $277,544 $221,591 $97,313 $395,190 $492,503 $343,242
36%
Present Value PayBack IRR
DL $221,591.24 3.49 36%
T5 $343,242.26
Table 6– SSL Lighting System Investment Over 20 Years
This analysis illustrates a 3.5 year payback calculation from the SSL intelligent lighting system today with
an internal rate of return (IRR) of 36% and a twenty-year Net Present Value cost positive result
compared to the T5 lighting system. Depending on the hurdle rate for technology investments, a 36%
internal rate of return suggests that even at a higher upfront cost, a solid state lighting system could be
a good capital investment as long as reliability is in place.
Facility Manager and Employee Feedback
The initial installation of LED showed a few fixtures had malfunctioned dimming, but was rectified by
Digital Lumens and new fixtures replaced within a week.
Grant Chapman, the project lead and facility engineer at Interstate Warehouse was asked if the LED
system was a good example of an interior high-bay lighting system. He indicated a positive response
and satisfied with products that appeared to perform as promised by Digital Lumens.
When asked to rate the LED fixtures on a scale of 1 to 5 in terms of meeting expectation (where
1=Extremely Satisfied and 5=Extremely Dissatisfied) the Digital Lumens products were rated as 1 for
brightness, 2 for Glare and 3 for color, with “the cooler light that required some getting used to.”
There were some initial issues with the lack of sensitivity of fixture occupancy sensors. The LEDs would
not detect the presence of employees and fork trucks immediately. That issue seemed to be resolved by
Digital Lumens within a few weeks.
Negative comments centered on glare. Employees reported LEDs as “too bright and employees needed
some time to get used to the warehouse, especially going from dark to light.” Also, glare was cited as a
nuisance for some employees when identifying written descriptions on boxes in the warehouse.
10
11. Conclusions
This project has successfully demonstrated the efficiency gains that could be realized from an intelligent
solid-state lighting system. Continued measurement and validation, especially on long-term light
maintenance will assure that solid-state lighting systems will add more value compared to conventional
fluorescent lighting.
With the expectation of further efficiency advancements expected over the coming 2-3 years, it is
anticipated that LEDs will outperform conventional fluorescent lighting technologies, especially from
leveraging energy-saving control strategies for commercial lighting applications. The promise of more
robust performance of solid state lighting systems are based on extrapolations rather than field
experience and continues to warrant the understanding of risks associated with immature technology.
11
12. Appendix A – Digital Lumens Product Specifications
12
14. Appendix B – Photometric Data Points @ 6,000 Hours
31 16.1 31.2 fc
32 16.0 30.5 fc
33 15.5 29.7 fc
34 14.7 28.2 fc
35 14.0 27.0 fc
36 14.4 27.5 fc
37 15.3 29.3 fc
38 16.1 30.6 fc
39 16.9 32.2 fc
40 16.2 30.9 fc
41 15.2 29.2 fc
42 14.3 27.6 fc
43 15.0 28.8 fc
44 15.3 29.2 fc
45 15.3 29.2 fc
46 14.6 28.2 fc
47 14.3 27.6 fc
48 15.2 29.2 fc
49 16.3 31.3 fc
50 17.3 33.0 fc
PHOTOMETRIC DATA 51 16.3 31.1 fc
POINTS PHOTOPIC SCOTOPIC 52 15.7 30.0 fc
1 14.4 27.4 fc 53 15.2 29.1 fc
54 14.8 28.3 fc
2 13.7 26.0 fc
55 15.1 29.0 fc
3 13.9 26.3 fc 56 15.8 30.3 fc
4 14.5 27.2 fc 57 16.3 31.2 fc
5 15.3 28.8 fc 58 15.8 30.3 fc
6 15.7 29.6 fc 59 14.8 28.5 fc
60 14.1 27.1 fc
7 16.1 30.3 fc
61 15.1 29.2 fc
8 14.4 27.1 fc 62 15.9 30.7 fc
9 13.4 25.4 fc 63 15.9 30.4 fc
10 13.1 24.7 fc 64 15.2 29.0 fc
11 13.7 26.0 fc 65 13.9 26.7 fc
66 13.2 25.3 fc
12 14.4 27.2 fc
67 12.4 24.0 fc
13 14.5 27.5 fc 68 13.5 25.8 fc
14 14.7 27.7 fc 69 14.4 27.8 fc
15 14.2 26.9 fc 70 14.7 28.4 fc
16 14.0 26.6 fc 71 14.5 27.8 fc
72 14.1 27.2 fc
17 14.3 27.2 fc
73 13.6 25.8 fc
18 15.1 28.6 fc 74 13.6 26.2 fc
19 15.6 29.4 fc 75 14.2 27.5 fc
20 14.4 27.1 fc 76 15.2 29.4 fc
21 12.9 24.4 fc 77 15.2 29.3 fc
78 14.2 27.3 fc
22 12.2 23.3 fc
79 13.7 26.3 fc
23 13.2 25.0 fc 80 14.3 27.6 fc
24 13.7 26.1 fc 81 14.9 28.7 fc
25 15.1 28.7 fc 82 15.1 29.0 fc
26 15.9 30.2 fc 83 16.3 31.2 fc
27 15.8 30.1 fc 84 15.1 29.1 fc
85 14.0 26.9 fc
28 15.4 29.5 fc 86 13.2 25.3 fc
29 14.2 27.3 fc 87 13.2 25.4 fc
30 14.7 28.1 fc 88 14.3 27.1 fc
14
