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Dark Sky Lighting and Energy Savings
Gary Schroeder RMUE September 26, 2019
2003 Northeast Blackout
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Dark Sky Lighting and Energy Savings Gary Schroeder RMUE - - PowerPoint PPT Presentation
Dark Sky Lighting and Energy Savings Gary Schroeder RMUE - - PowerPoint PPT Presentation
Dark Sky Lighting and Energy Savings Gary Schroeder RMUE September 26, 2019 1 2003 Northeast Blackout 2 The Energy Cost of Light Pollution 30% of all outdoor lighting is wasted, ending up in the night sky International Dark-Sky
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The Energy Cost of Light Pollution
- 30% of all outdoor lighting is wasted, ending up in the night sky
International Dark-Sky Association (www.darksky.org)
- Unshielded outdoor lights waste $2 billion (17 terawatt-hours) of
energy in the U.S. each year
- Equivalent of 8.2 million tons of coal burned annually to light up the
night sky
https://www.scientificamerican.com/article/outdoor-light-pollution/ http://adsabs.harvard.edu/full/1991ASPC...17...89H
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Skyglow Brightening of the night sky over inhabited areas
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Light Tresspass
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Light falling where it is not intended, wanted or needed
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Glare
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Excessive brightness that causes visual discomfort or disability
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Light Clutter
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Bright, confusing and excessive groupings of light sources
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Safety and Security
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Lighting Best Practices
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Saddlebrook Townhomes
- 102 Townhomes
- 172 Porch/deck lights
- 65 Post-top lights
- City Neighborhood Innovation Grants
- 2017 – Porch Lights
- 2018 – Post-top Lights
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Saddlebrook Townhomes Porch Lights
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Old New
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Saddlebrook – Out with the old
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Sample of original bulbs Original fixtures
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Porch Lights
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Before After
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Unshielded vs Shielded Porch Light
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Max Luminance: 7,732 cd/m2 Ground Luminance: 0.66 cd/m2 Max Luminance: 170 cd/m2 Ground Luminance: 1.66 cd/m2
Unshielded: 46x brighter (Glare) Shielded: 2.5x more light on porch Old New
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Post-top Fixtures
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Before After
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Post-top fixture retrofit
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Post-top light metrics
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Max Luminance: 10,000 cd/m2 Ground Luminance: 0.1 cd/m2 Max Luminance: 56 cd/m2 Ground Luminance: 0.6 cd/m2
Unshielded: 180x brighter (Glare)! Shielded: 6x more light on ground Old New
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Saddlebrook Night Sky Event 7/9/2019
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Energy Savings
Porch lights
- Baseline = 60 Watts average, New fixtures = 9 Watts
- 172 Fixtures
11,526 kWh/yr Savings Post-top lights
- Baseline = 6.3 Watts (previous 60 Watts), New fixtures = 10
Watts
- 65 Fixtures
- 1,053 kWh/yr Savings
Net Savings = 10,672 kWh/yr ≈ $1,000/year
(possibly some take-back from more people leaving their porch lights on)
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Lighting Value / Distribution Efficiency
Porch lights
- 60 Watts → 9 Watts (85% savings)
- 800 lumens → 750 lumens
- 13.3 lumens/W → 83.3 lumens/W (↑525%)
- Luminance Efficacy: 0.011 Cd/W → 0.184 Cd/W (↑1,577%)
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Lighting Value / Distribution Efficiency
Post-top Lights
- 6.3 Watts → 10 Watts (↓59% savings)
- 450 lumens → 450 lumens
- 71.4 lumens/watt → 45.0 lumens/watt (↓37%)
- Luminance Efficacy: 0.016 Cd/W → 0.060 Cd/W (↑278%)
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Other Benefits
- Measure persistence – integral LEDs
- Uniform look in neighborhood
- Better light distribution
- Safety/security
- Quality of life – “I now enjoy sitting out on my patio at night without
being bombarded by glaring lights” (resident referring to old post- tops)
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Typical Box Store Offering
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Fort Collins Utilities / Efficiency Works Rebates
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https://efficiencyworksrebates.com/
- Integral LED
- Fully shielded
- 3000K or less
$25 RaaS
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Suggested Path Forward for Outdoor Lighting
- Provide rebates only for lighting fixtures that are night-sky friendly
- Disqualify “glare bombs”
- Implement color temperature requirements (e.g., 3000K or less)
- Create channel for homeowners and businesses to purchase quality
fixtures.
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www.fcgov.com/nightsky
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Thank you!
Gary Schroeder
- Sr. Energy Services Engineer