abcs of led street lighting - iowa association of ...archive.iamu.org/conference/energy...

Iowa Association of Municipal Utilities

ABCs of LED Street LightingAnne Kimber, IAMU

[email protected], 515 289 1999 ext 213October 1, 2013


Outline• Background on LED street lights• Some pointers on planning a retrofit• Example of an RFP process for a joint purchase• Results, Conclusions


IAMU‐ 136 municipal electric utilities‐half have fewer than 800 meters.

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A street lighting project is one of the most visible energy efficiency projects a community can undertake, and the cost savings benefit all.

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From municipal energy analysis: Street lighting on average is 26% of municipal energy consumption in small towns

One example of Municipal Street Lighting Energy Use


Street Light Terminology• Lumen: total amount of visible light emitted by a source

(lm)• Efficacy: the ratio of power emitted as light to the total

input power to the luminaire (lm/Watt)• Footcandle: lumens per square foot (lm/ft2)• Illuminance: lumens of light arriving at a unit of road

surface (footcandles or lux)• Luminance: the brightness of a light source in a

particular direction, or as reflected from a road surface and seen by an observer (candela/m2)

• Correlated Color Temperature: the color of light produced by a light source, (degrees Kelvin).

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Frequently Asked Questions

How is LED lighting different from other street lighting technologies?

– Better control of light distribution pattern and improved uniformity:

• High Pressure Sodium lamps are high intensity discharge near‐point sources… leading to hot spots of illumination

• LEDs are multiple point sources which can be directed in a particular distribution pattern to increase uniformity

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HPS vs LED

While HPS luminaires are more uniform, one manufacturer to another, LED luminaires vary greatly…

250 W HPS Type III 250 W equiv LED Type III


Will LED street lighting improve lighting quality?2 Answers:‐Increased Uniformity‐Higher Correlated Color Temperature with LED (higher blue light content contributes to visibility)

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Impact of LED on Roadway lighting design

• Lighting criteria for photopic (high light) versus mesopic (low light) conditions

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Figure 3 from handbook: photopic (black) and scotopic (green) luminosity functions

Lighting criteria currently designed for Photopic (high light) conditions

Mesopic conditions are the low light levels for which we provide streetlighting

Scotopic: almost complete darkness


LED impact on roadway lighting design

• In dim light (mesopic conditions, our eyes are more sensitive to light that has more blue content.

• That means that new roadway lighting designs using LEDs may be able to reduce the design standard for required illuminance.

• San Jose Street Light Design Guide has method for calculating required illuminance with LEDs…..and the next revision of RP‐8 is widely expected to include this topic.

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FAQs continued• “Will LED street lighting save energy?

– Greater efficacy (greater lumens of light output per watt of power input) of LEDs AND more uniform lighting distribution will save energy

– From case studies, LEDs reduced energy consumption from 29‐63%.

– Caution: must evaluate existing system: over‐lit areas? Auburn example

• “Do LED street lights last longer than HID lighting– Yes. In IAMU’s joint purchase the estimated life of the LEDs is in

excess of 20 years.– Caution: Need good warranty from manufacturer

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LED wild claims

• Pocahontas, Iowa

• Nominal 80 Watt induction • delivering 5,600 lumens • promoted as replacing • 150 watt HPS delivering• 16,000 lamp lumens

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FAQs continued

• “How will LED street lights reduce our maintenance costs”?– The long life of LED luminaires will reduce re‐lamping costs– Caution: Must match LEDs with Long‐life photocontrols

• “Will installing LED street lights reduce our overall costs?”– YES, and maintenance savings can be significant. Need to analyze energy and maintenance cost savings using IAMU simple spreadsheet tool or by using the MSSLC financial calculator

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FAQs continued

• “Has the public liked the change from the yellow‐orange of HPS to the white‐blue of LED?”– IAMU case studies: YES‐ great public reaction, or people didn’t notice the change

– Suggest installing a test fixture and asking for community feedback (Algona did this)

– Web resources on MSSLC Gateway demonstration projects such as Kansas City

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FAQs continued

• “What about street lights shining in people’s windows. Will LED street lights solve this problem?”– Design of LED optics can eliminate this problem– Select LED distribution pattern carefully

• “Are there best practice design guides for street lighting?”– RP‐8 (2005)– AASHTO GL‐6 (2005)

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FAQs continued

• “How do we know if a luminaire’s light distribution pattern is appropriate?”– There are 7 major distribution patterns, in IAMU’s joint purchase we referred to light distribution pattern III (3).

– For LEDs, photometric calculations needed to ensure adequate lighting

– Suggest using RP‐8 as local standard

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Luminaire Light Distribution Patterns

Figure 2 from the handbook. Modified with permission from Lighting for Exterior Environments (RP‐33‐99) published by the Illuminating Engineering Society of North America.

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Type II and III used in our roadway designs


FAQs continued

• “Are there any local, state or national regulations regarding street lighting?”– Local jurisdictions set regulations for street lighting within a community.

– Some communities have adopted• RP‐8 • or AASHTO GL‐6

– International Dark Sky Association Model Ordinance

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FAQs continued

• “Can we install the LED luminaires on existing poles and arms?”– Yes, but….pole height and spacing may not be optimal so try to match the new illuminance level to existing illuminance.

– Most LED luminaires are designed to replace existing HPS on existing poles

– Need to specify the mounting configuration needed for the existing arm

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FAQs continued

• “Does it make sense to replace decorative luminaires with LED?“– We have focused on cobrahead and barn light retrofit– Greater complexity in specifying retrofit LED decorative luminaires

– Sacramento study indicates costs greater than benefits

– Expecting rapid technology changes to bring better solutions. Pulse start metal halide bulbs may be a better solution.

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FAQs continued

• “How do we know if we’re getting a good product?”– Request for Bid process is recommended– MSSLC model specification tool

• “Are there standard LED replacement luminaires for existing luminaires?”– In a word, “no”. Significant variation. – Kansas City, Portland and Pittsburgh test cases

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FAQs continued• “Should we use an LED lamp that screws into the existing HPS luminaire?”– LED optics are very different from HPS.– Use a high quality luminaire specifically designed for LED to optimize light distribution

• “Are there replacement parts? What happens when the light “burns out”– LED chips more likely to dim– The “L70” factor refers to the number of hours at which the LEDS have dimmed to 70 percent of its original light output.

– More likely that the driver or photo control will fail first

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FAQs continued (last of these!)

• “Should we use standard photocells…”– To save maintenance costs, use long‐life photocells

• “Are there more advanced ways to control LED luminaires?”– LEDs are instant‐on and can be effectively dimmed– Dimming saves energy and extends the life of the LED

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Federal and State Standards

• New efficacy standards– Iowa: 66 lumens/Watt– Minnesota: 70 lumens/Watt

• No USA‐wide list in 2012 of state standards like Iowa and Minnesota

• In Iowa Statewide Urban Design and Specifications (SUDAS) refers to RP‐8 but go beyond to include design criteria for LED roadway lighting, and include the Iowa efficacy standard

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Starting an LED projectInventory your system: (see handout)

– What areas do you want to focus on first? • Over‐lit areas?• Residential versus commercial areas? (case studies vary)• Revitalization project?• Measure “before” light levels?

Good knowledge of not only wattage of existing fixtures but also– Spacing– Pole height– Luminaire weight limits– Street criteria

• Enables you to write a tighter specification and use the MSSLC DOE Model Specification with the “System” appendix.

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What is Project success

Retrofit improves lighting quality and safety• Inventory your system before you start

Good quality fixtures last: • Good specification• WARRANTY

Both energy and O&M costs are reduced• Street light cost calculator

Competitive pricing through bid process• Save $ through RFP based on MSSLC model specification

Community pleased with the new lightingTry some test fixtures to gage community reaction


DOE Municipal Solid‐State Street Lighting Consortium (MSSLC)

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• Free membership• Objective evaluation of street and area lighting products• Members are part of an international knowledge base• E-Newsletter and webinars• Study reports• Model Specifications• Financial analysis calculator• http://www1.eere.energy.gov/buildings/ssl/consortium.html


Cost/benefit calculators

IAMU has a simplified version of MSSLC toolMaintenance savings are significant: assumptions?– Significantly lower re‐lamping labor and bucket‐truck costs due to assumptions about LED life‐span

– Important to use long‐life photocells to match expected life of LED fixtures

– Operating at higher drive currents can shorten lifetime decrease maintenance savings

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LED retrofit joint purchaseIDEA: IAMU and Lighting Consultant Mike LambertDevelop RFP process for municipal utilities for LED retrofit of high pressure sodium cobra head luminairesAdvantages:

–Assist participants to meet EECBG grant requirements and Iowa Efficacy requirement–Independent process with technical assistance to evaluate proposals–Provide economies of scale–Tool: the new DOE MSSLC Model Specification

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IAMU modified the MSSLC material specification:

Added intro on Bidder requirements (experience with LEDs, volume of LED projects, etc)

• pricing for break‐points • additional Warranty‐ DOE has 5 year, we asked for 10 year, with additional pricing

• Show compliance with Buy American provision (to comply with ARRA funding)

• Show compliance with Iowa statute on efficacy of 66 lumens/Watt

Specific fixtures‐ we limited proposals to a few fixtures for each HPW wattage we were replacing: (why? – we reviewed photometric data for each fixture, e.g. the lighting distribution patterns, drive currents, etc.)


Joint Purchase–15 municipal utilities participated initially–Initial purchase: 1,154 LED lights installed in Iowa –Luminaires expected to result in annual energy savings of approximately 574,000 kWh –Life expectancy greater than 20 years–Project funds invested expected to realize a simple payback well within the life of the fixture based on energy savings alone. –Luminaires expected to yield significant annual operation and maintenance savings for the participating communities

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RFP Results: Quoted Prices Shown Relative to Low Bid

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250 W HPS Retrofit Quoted Price

RFP Results: Quoted Prices ShownRelative to Low Bid

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RFP Results: Quoted Prices Shown Relative to Low Bid

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Results ‐ Reviewing Bids – Mean Price & Standard Deviation

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250W HPS Retrofit

150W HPS Retrofit

100W HPS Retrofit

Mean Price from Bid $645.57 $492.52 $361.53Standard Deviation $98.17 $66.13 $80.84


Two Examples of Joint Purchase Communities, included in the Handbook

• Algona, Iowa‐ leader in the project• Auburn, Iowa, retrofit 400 W HPS to 104 W LED


Algona, Before

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Algona, After


Algona, Iowa ‐ Population: 5,560 Energy Savings: 42%

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LED Retrofit Project Summary for: Algona, IA

Total Costs (Fixture cost, warranty, consulting fee, photo‐controls, estimated installation labor) $288,815Total Fixtures Ordered Thru Purchase 447150W HPS ‐ 104W LED Replacements 55250W HPS ‐ 104W LED Replacements 28250W HPS ‐ 176W LED Replacements 364Annual kWh Savings 234,254Annual Energy Cost Savings* $18,740

Estimated kWh Savings at 70000 Hr 3,743,782Estimated Energy Cost Savings at 70000 Hr $502,157Estimated Payback Period (Energy Savings Only) 15.4Estimated Payback Period (Includes maintenance savings) 9.2

*Estimate based on the following rate ($/kWh): $0.080

Iowa Association of Municipal Utilities 40

Iowa Association of Municipal Utilities 41


Quote from Algona Municipal Utilities GM

“The fixtures that we've put up so far … have met expectations. Easy to install, good quality, and the community folks that have been out have been very impressed with the light. … We have had positive community response from the fixtures that have been installed. We've let people know in our local media, through board of trustees meetings, through city council meetings, and it's been very positive.”

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Annual kWh Savings– 573,877 kWh

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UtilityTotal Annual Energy Savings

Estimate (kWh)Percentage of Energy Savings

(Retrofit Only)Afton 6,745 59%Algona 234,254 42%Anita 46,547 50%Anthon 4,568 56%Auburn 37,864 78%Earlville 11,038 45%Graettinger 16,372 41%Greenfield 736 45%Montezuma 21,460 41%Rock Rapids 67,759 40%Rockford 12,816 59%Sergeant Bluff 45,346 40%Stratford 12,847 43%Tipton 42,035 49%Westfield 13,490 59%Total 573,877 45%

Estimated Annual Energy Savings and savings as a percent of pre‐retrofit use

Case Study Community

Total Number of Retrofits

Estimated Annual Energy Savings from LED Retrofits

(kWh)

Energy Savings as Percentage of Original Energy Usage Pre‐

RetrofitAlgona 447 234,254 46%Auburn 24 37,864 78%Independence 204 99,154 45%Montezuma 41 21,460 41%Mount Pleasant 130 70,378 57%Muscatine 301 155,534 51%Pocahontas 255 105,639 43%Spencer 153 57,632 29%Waverly 1010 403,805 63%Totals 2565 1,185,720 50%

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Conclusions:

• LED street light technology is mature enough for successful projects that are cost‐effective.

• Essential resources in selecting LED new or retrofit street lights include:

• DOE CALiPER Reports • DOE MSSLC model specification• Good inventory and understanding of system operation• Robust RFP process • Technical assistance for layout and bid process

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