Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Measuring Light Pollution - How New Technology is Making it Possible.

608 views

Published on

25 years after the term “light pollution” was coined, we still have a hard time understanding what it is. Measuring it is difficult and metrics to describe it are still being developed. Innovative techniques like all-sky imaging and high dynamic range photography are finally making it possible to accurately measure night sky brightness and glare. International Space Station and satellite imagery is also being used to measure global sky brightness and document trends in its proliferation. This session will demonstrate how to measure different aspects of light pollution and examine the metrics that have been developed to quantify it.
Presented by: Bob Parks
Smart Outdoor Lighting Alliance

Published in: Technology
  • Be the first to comment

  • Be the first to like this

Measuring Light Pollution - How New Technology is Making it Possible.

  1. 1. What is it, how do we measure it, and how do we fix it? Bob Parks, MIES, LC Executive Director Smart Outdoor Lighting Alliance (SOLA) bparks@sola.lighting
  2. 2. Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request. This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. ___________________________________________ Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
  3. 3. Twenty five years after the term “light pollution” was coined, we still have a hard time understanding what it is. Measuring it is difficult and metrics to describe it are still being developed. Innovative techniques like all-sky imaging and aerial photography are finally making it possible to accurately measure night sky brightness. International Space Station and satellite imagery is also being used to measure global sky brightness and document trends in its proliferation. This session will demonstrate how to measure different aspects of light pollution and examine the metrics that have been developed to quantify it.
  4. 4. *Define what light pollution is and how it can be measured. *Learn what metrics have been developed to quantify light pollution. *Demonstrate the tools and technology being used to measure night sky brightness. *Understand how new LED lighting technology may help to reduce it in the future.
  5. 5. Skyglow Glare Light Trespass Visual Distraction
  6. 6.  Most recognizable light pollution feature by public  Impacts astronomy, ecology and karma  Produced by the scatter of light interacting with moisture and particulate in the atmosphere  Light +/- 10 degrees of horizon causes most  Uplight and reflected light contribute  Different wavelength light behaves differently
  7. 7.  Different wavelength light scatters differently  Mie scattering defines light scatter in aerosols  Primarily responsible for “local” skyglow  Wavelength agnostic  Redirects light through moisture in all directions  Rayleigh scattering defines scatter through molecules  Shorter wavelength scatters more  Is what makes the sky blue, sunsets red  Characterizes skyglow visible at great distances
  8. 8.  Broad Spectrum White Light (LED)  Contains significant quantity short wavelength, blue SPD  Higher the CCT, the more blue SPD  Scatters 3-5 times more than longer wavelength  If installed at same intensity as HPS, skyglow is 3-5x greater  White LED starts as blue, white light is created by converting blue SPD centered at ~460nm with phosphor  The blue 460nm peak corresponds with the circadian detector cells in every species.
  9. 9.  Caused by light directed into eyes, not target area  IES defines light range of 60 – 90 degrees of nadir  Defined as “nuisance” or “disability”  Dramatically degrades visibility  Requires increased lighting levels to compensate  Often the byproduct of “enhanced” uniformity  Product of poor lighting design  Disproportionately impacts seniors due to the physiology of the aging eye
  10. 10.  Created by light directed onto adjacent properties  Caused by poor design, ignorance and insensitivity  Most common public complaint to authorities  Disturbs quality of life and karma  Subject of frequent lawsuits and violence  Property rights vs. “quiet enjoyment”  Byproduct of poorly installed “security” lighting  Local DOTs responsible for most light trespass  #1 reason for development of most lighting ordinances
  11. 11.  Methodology  Metrics  Tools and technology
  12. 12.  Methodology  Measurements from Earth’s surface - Night Sky Brightness  Aerial measurements – Direct and reflected luminance  Measurements from space (ISS and satellites)
  13. 13.  Metrics  Bortle Scale – Night Sky Brightness  Uses limiting magnitude of stars for comparison or photometer measurements  Measurements can be made visually  Uses zenith measurements (normally darkest)  Scale of 1 to 9 is not very intuitive (9 is worst)  Doesn’t account for skyglow at horizon
  14. 14.  Metrics  Sky Quality Index (Developed by NPS) – Night Sky Brightness  Uses calibrated photometer and star “plate-solving”  Extremely accurate  Starts by calculating “natural sky” as a basis  Then calculates the anthropogenic (man-made) portion  Measures the entire sky with 26 separate images  Samples are weighted based on location in sky  Scale of 0 – 100 is easy to understand (0=Bad/100=Good)
  15. 15.  Tools and technology  Photometers  Range in cost from free to very expensive  Accuracy and repeatability increase with cost  Typically measure a very small portion of the sky  Measurement of luminance in candela per meter squared (cd/m2)  Astronomical CCD and DSLR Cameras  Need to be calibrated as a system (camera + lens)  Can capture entire sky in single image with fisheye lens  Uses computer to create luminance calibrated color map
  16. 16.  Potential advantages of LED  Superior distribution of light possible  White light can provide same visibility with less lumens  SPD of LED can be designed to reduce glare, skyglow and ecological impact on plants, animals and humans  Adaptive controls can dim and change SPD dynamically  Amber LED can replace LPS near observatories
  17. 17. 5000K CCT 2200K CCT
  18. 18. Amber LED
  19. 19. Dynamically SPD Tuned LED (EXO Optics)
  20. 20.  Does the public care enough to curb light pollution?  Historically every increase in efficacy has resulted in more lumens, not energy saving  Will energy costs and climate change effect our trajectory?  Public equates lighting with enhanced safety  Primal fear of the dark has beat out the night sky and environment for the last hundred years  Only 20% of public have ever seen a natural night sky  Who will miss something that they didn’t know existed?
  21. 21. Thank You. Questions? Bob Parks, MIES, LC Executive Director Smart Outdoor Lighting Alliance (SOLA) bparks@sola.lighting
  22. 22. This concludes The American Institute of Architects Continuing Education Systems Course

×