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HomeMy WebLinkAboutCOM 0038.004 2010-2012Murashige, From: Sent: To: Subject: Attachments: 1/19/2011 Laura exmm. 38 Richard Wainscoat [RJW @IfA.Hawaii.Edu] Wednesday, January 19, 2011 10:55 AM counciltestimony @co.hawaii.hi.us Testimony to County Council on Bill 12 Bi ll12 -cou ncil- testimony. pdf , • Page 1 of 1 PlcouNCn. 11 Comm. No. Ref. To: Pr all um J Ref. Date 2011 Testimony to County Council, County of Hawaii on Bill 12, to amend the County of Hawaii Outdoor Lighting Ordinance by Richard Wainscoat Astronomer, University of Hawaii Chairman, Light Pollution Working Group, Commission 50, International Astronomical Union The University of Hawaii supports the efforts by the County of Hawaii to install streetlights that use filtered light emitting diodes near signalized intersections and marked crosswalks. However, the University believes that the Bill has some flaws that need to be corrected. Mauna Kea is arguably the best site on Earth for astronomy; it is certainly the best site in the northern hemisphere. It was recently selected as the site for the Thirty Meter Telescope, which will become by far the largest telescope in the word when it is completed. A dark night sky is a fundamental requirement for astronomical research. The 1989 lighting ordinance has provided good protection for the night sky over Mauna Kea, but the sky is gradually becoming brighter. The reasons for the degradation of the night sky include population growth on the Island of Hawaii (and the lighting increases that come with this growth), continued use of partially shielded lights (that are allowed by the present ordinance), and lack of enforcement of the present ordinance by the county. An important change to the ordinance that Bill 12 will make is the use of fully shielded lights for all outdoor lighting in the county. This will eliminate light being emitted directly into the night sky from light fixtures, and is a critically important change. With fully shielded light fixtures, only light that is reflected from the ground can affect astronomical research. Bluer colors of light affect astronomy much more than redder colors. There are two reasons for this: 1. Bluer light is scattered much more efficiently than redder light by air molecules. This is called "Rayleigh scattering" and is the reason why the sky is blue in the daytime, and why sunsets are red. This is the principal mechanism by which artificial lighting is scattered back into the telescopes, artificially brightening the sky and making faint objects difficult to see. Rayleigh scattering is also the reason why stars cannot be seen in the daytime — the stars are all present in the sky, but the sky is too bright for us to be able to see them. Astronauts can see stars in the daytime because there is no air to scatter the sunlight. 2. The natural night sky is darker at blue wavelengths than it is in redder colors. This makes it easier to see very faint objects using bluer light. Most white light emitting diodes produce their light using a blue LED (emitting blue light near 450 nm where the eye is very insensitive, but the telescopes are very sensitive), and a phosphor that converts some of the blue light to green, yellow, amber and red light. The proposed intersection lights use a filter to remove the blue light, but transmitting the light emitted by the phosphor, with green, yellow, amber and red colors. The green light from these filtered white LEDs will affect astronomy, but we believe that the impact is acceptable provided that the following steps are taken: 1. The use of the filtered white LEDs is limited to the areas adjacent to signalized intersections and marked crosswalks as proposed in Bill 12. More widespread use of this type of lighting will introduce an excessive amount of green light into the night sky. Astronomers throughout the world use two standard filters, one of which spans the wavelength range from 400 nm (violet) to 550 nm (yellow - green). It is very important to continue to protect this wavelength range. 2. The county adds new limitations to blue /green emission from other broad spectrum lighting allowed as Class I and Class III lighting. The most practical way is to limit their Correlated Color Temperature (CCT). We propose limiting new Class I lighting to CCT < 4200K (the color of moonlight), and Class III lighting to CCT < 3000 K (the color of an incandescent light). We believe that these limitations will have little or no impact on the users of Class I and Class III lighting, but will have tremendous benefit to astronomy by reducing the amount of blue light from these sources. White LEDs can be very damaging to astronomy. High CCT LEDs emit tremendous amounts of blue light. The human eye is very insensitive to this blue light, but the telescopes are extremely sensitive, and the sky is very dark in the blue. The proposed limitations on the color temperature of Class I and Class III lighting detailed above will limit the blue content of these lights, and are vitally important to the continued protection of the night sky for astronomy. Low Pressure Sodium (LPS) is still the most energy efficient light source in terms of amount of light produced (lumens) per Watt of energy. Light emitting diodes (LEDs) still produce less light per Watt. Because of the desire to save energy, the proposed intersection LED lights produce much less light than the LPS lights they will replace. The new fixtures therefore must direct the light they produce very efficiently, directing it only to where it is needed, spilling very little light away from the roadway, and no light directly into the night sky. Many of the safety concerns related to the present LPS lighting on the Island of Hawaii relate to the fixtures not being properly shielded. LPS lighting is still in widespread use across the world, including wide usage on Oahu, near major observatories, across the UK (because of its energy efficiency), and in environmentally sensitive areas (such as Florida). We believe that use of amber LEDs as Class II lighting away from intersections is an acceptable alternative to LPS. Amber LEDs are widely available, and are already in use for roadway lighting in environmentally sensitive areas such as Florida. The energy efficiency of amber LEDs is competitive with white LEDs. Amber LEDs emit red, orange, amber, yellow and a small amount of green light. They produce much better color rendition than LPS. Careful use of amber LEDs will allow roadways and parking lots to be illuminated using less total light then LPS. This can benefit astronomy, and also improve safety, provided that fully shielded fixtures are mandated. We believe that the present draft of Bill 12 has an unnecessarily complex categorization of Class I lighting. The "Others" category should be collapsed into a single line. The explicit mention of the filtered LEDs in Class I lighting is unnecessary because it is already include in "Others." We request that 400 nm is replaced by 350 nm in the definition of blue light content. This change will have no practical impact on the proposed LED intersection lights (which emit essentially no light between 350 and 400 nm), but will protect the ultraviolet region of the spectrum between 350 and 400 nm. This part of the spectrum is also very important to astronomy; it is irrelevant to streetlighting because the human eye cannot see light with these wavelengths. Insects are very sensitive to light in this part of the spectrum, so limiting ultraviolet light is also environmentally wise. The following three pages summarize, in simplified form: 1. The present lighting ordinance, 2. The ordinance as proposed in Bill 12, and 3. The changes requested to protect astronomy on Mauna Kea. We respectfully request that the County Council modifies Bill 12 to address the concerns that we have raised. Current Lighting Ordinance Lamp type Class I (business and sports) Low pressure sodium Others Class II (streets and parking lots) Low pressure sodium < 90 Watts Low pressure sodium > 90 Watts Others Class Ill (decorative effects) Low pressure sodium Others above 4,050 lumens Others below 4,050 lumens Neon Shielding Restrictions Partially shielded None Fully shielded Off 11pm to sunrise None None Partially shielded None Prohibited Fully shielded Fully shielded None None Prohibited Off 11pm to sunrise Off 11pm to sunrise County Proposed Lighting Ordinance Lamp type Class I (business and sports) Low pressure sodium Others Class II (streets and parking lots) Low pressure sodium LED fixtures with less than 2% blue light content Others Class Ill (decorative effects) Low pressure sodium Others above 4,050 lumens Others below 4,050 lumens Neon Shielding Fully shielded Fully shielded Fully shielded Fully shielded Restrictions None Off 11pm to sunrise None Streetlights within 1,320 ft of signalized intersection or 100 ft of marked crosswalk Prohibited Fully shielded None Prohibited Fully shielded Off 11pm to sunrise None Off 11pm to sunrise Lights installed prior to 2011 that are in conformance with 1989 lighting ordinance may remain in service until they need to be replaced. Astronomy Proposed Lighting Ordinance Lamp type Class I (business and sports) Low pressure sodium Others with CCT < 4200K Others with CCT > 4200K Class II (streets and parking lots) Low pressure sodium LED fixtures with less than 2% blue light content Amber LED Others Class Ill (decorative effects) Low pressure sodium Others above 4,050 lumens Others with CCT > 3000K Others below 4,050 lumens and CCT < 3000K Neon Shielding Restrictions Fully shielded None Fully shielded Off 11pm to sunrise Prohibited Fully shielded None Fully shielded Streetlights within 1,320 ft of signalized intersection or 100 ft of marked crosswalk Fully shielded None Prohibited Fully shielded Fully shielded None None Prohibited Prohibited Off 11pm to sunrise Off 11pm to sunrise An amber LED is defined as a Light Emitting Diode that emits less than 2.5% of its light power below a wavelength of 550 nm. CCT = Correlated Color Temperature Lights installed prior to 2011 that are in conformance with 1989 lighting ordinance may remain in service until they need to be replaced.