Greatest Energy Efficiency, Minimum
Negative Impacts, and Preservation of
Dark Skies: New Best Practices for Street
and Area Lighting
James R Benya, PE, FIES, FIALD
BENYA BURNETT CONSULTANCY
Davis, CA
Game Changers
• AMA June 2016 position on
outdoor lighting
• DLC listing of LED street lighting
products
• Rapidly increasing efficacy of LED
• Rapidly falling prices of LED
• “Smart” city promotions
• Renewed public concern over
light pollution
Game Changers
• Demand for appealing
lighting
• Demand for warm toned
comfortable lighting
• Demand for low-glare
lighting
San Diego Gaslight District, compl. 2015
First GE LightGrid Wireless Smart City
system
Light Pollution is Measured by the Bortle Scale
Energy Efficiency
Driving the LED Revolution
LED Source Efficacy
Current LED efficacy
• Approaching optimal 180 lumens per watt
• Typical values 150 lumens per watt @ 70 CRI
• Difference in efficacy among common LEDs less than 5% between
4000K and 3000K
• Difference between 3000K and 2700K less than 7%
LED Overall Efficiency
Combining three factors
• LED efficacy, including driver losses and optics, >115 LPW versus ~80
LPW for high pressure sodium (100 to 200 watt class)
• LED’s superior uniformity
• Change of RP-8 from illuminance to luminance
Net opportunity achieved in Tucson Arizona = 65% energy savings using
3000K
Phoenix evaluation of less than 6 month payback extension to go from
3000K to 2700K.
Efficiency Summary
• Take full advantage of LED efficiency in LPW and optics
• Take advantage of luminance based metrics and the bettered
uniformity of LED
• Seek to achieve >50% energy reduction not including adaptive
controls
Negative Impacts of LED
Not perfect and can be acceptable if done right
Light pollution
• Anthropogenic sky glow
• Light trespass
• Glare
• Health and wellness impacts
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Humans
Plants and crops
Mammals
Insects
Fish
Primary Cause of LED Light Pollution:
Spectrum
• Excessive short wavelength light especially in low CRI/high efficacy
sources
• Impact on iPRG cells in human eye
• Impact on similar issues with all living beings
• Cause of glare stress response (more than sensation)
• Age-related sensitivity to short wavelength light
• Increased Rayleigh Scattering and anthropogenic sky glow
LED Lighting’s Dirty Secret: Lots of Blue
LED’s can be better using lower Color
Temperature
2700K now being recommended for our
residential street lighting projects
4000K promoted by US DOE and by many
lighting manufacturers
Moonlight versus streetlight
Alternative: 2200K LED
might appear more like
moonlight
Trend: establish limits on the
percentage of energy between 380
and 500 nm relative to the entire
visible spectrum
Manufacturers Make It Worse
• Increased high angle glare (lower hemisphere very high and high zones)
• Extremely high luminance
• Efficiency over quality
• Limited shielding options
Efficiency, uniformity
Glare, pixelization
VS
Simplicity, softness, low glare
Pooling of light, non-directional
Design Considerations
Well designed lighting can solve most problems
AMA Position on 3000K is for Real
• Was the third time AMA has tried to get the lighting industry to listen
• IDA issued a warning paper in 2010 that was ignored by industry and
DOE
• Lawyers are already organizing class action suits in cities with 4000K
and higher LED lighting
• Industry and DOE pushing back
There are alternative white light sources
• RP-8 does not address S/P ratio for roadway lighting tasks
• Minimum S/P difference between 2700K and 4000K for peripheral
tasks
• Considerable difference in S/P ratio between LPS or HPS and 3000K
LED
• In replacing LPS or HPS with 3000K LED, there will be a significant
increase in S/P ratio and improved peripheral vision
• There will also be an increased sense of brightness and related sense
of security and safety
There are alternative light sources
• Very low CCT white light sources (2000K, 2200K, 2400K)
• Blue-free filtered LED (FLED) 2200-2500K
• Phosphor coated wide-band amber (PC Amber or WBALED) 20002200K
• Narrow band amber (NBALED) suitable for sea turtle nesting areas
International Astronomical Union’s
Recommended Mitigation Measures
1. Fully shielded light sources
2. Reduced light levels
3. Spectrum improvements
Reduced Light Levels May be Possible
• IES Recommended Practice RP-8-14 for Roadway Lighting
• IES Design Guide DG-21-15 for Residential Streets
• Many communities do not meet RP-8 (any generation)
• Communities are not necessarily required to provide lighting or to
meet standards
• Community-centric light levels
• RP-33, ASHRAE/IES 90.1, LEED, the IDA/IES MLO, IES RP-15-11 (BUG
system) and the IES HB agree on the use of a five lighting zone system
Suggested Community Actions
Straightforward, easy steps
Develop Local Lighting Standards
• Lighting Zone Based
• Community-wide master plan and planning-based community
decision on the role of lighting
• Develop
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Roadway and street standards by lighting zone
Community lighting ordinance by lighting zone
Amortization time frame
Unique and special conditions of the community
• Determine financial benefits and costs
Implement Standards
• Replace City-wide street lighting as soon as practical
• Implement and enforce lighting ordinance
• Begin amortization period on privately owned lighting
• Work with local utilities to incentivize LED replacements
• Make certain that the utility is aware of color temperature and shielding
requirements
Davis, California
• Removed over 4,000 sag lens high pressure sodium street lights
• Replaced 250 watt arterial street lights with fully shielded 130 watt
LED (save 160 watts each)
• Replaced 100 watt residential street lights with fully shielded 19 watt
LED (save 101 watts each)
• Replaced 70 watt green belt bikeway lights with fully shielded 10 watt
LED (save 76 watts each)
• Residential and green belt lighting at 2700K
• House side shields and cul-de-sac shields when requested
The “Smart” City
A necessary evolution
Candidate Elements of a “Smart” City Infrastructure
• Secure communications backbone
• City wide surveillance and sensor system
• Possible smart car network
• City wide web access
• Emergency communications network
• Emergency control and advisory network
• Control street lights and other publicly-owned systems
Public-private possibilities
• Citywide WiFi
• Citywide LiFi
• High resolution high speed cellular
• Rental of civic real estate to pay for city’s unique needs
Questions?
www.benyaburnett.com
[email protected]