Williamsburg Lights - Arlingtonva
From: John Seymour [mailto:[email protected]] Sent: Sunday, March 13, 2016 2:51 PM To: Erik Gutshall ([email protected]) <[email protected]>; Robin Leonard Cc: Gail Harrison ; Larry Suiters <[email protected]> Subject: Williamsburg Lights Erik and Robin: I have examined Musco’s responses to my technical questions and thought that it might be helpful — before this week’s meeting — to “review the bidding.” The Working Group has held a number of meetings to date to discuss technical and other issues and Musco has, to its credit, generated some conceptual site plans with projected luminance, glare, and light spill (among other measures). As we have all learned, these issues are quite complicated and are more uncertain at this site because of the introduction of a lighting format — LED — which is relatively new to sports fields. I have attempted (as a layman) to understand some of the issues and to draft questions exploring potential or likely adverse effects and their mitigation. State of Play: As I understand it currently, Musco has concluded (correctly, in my view) that the most commonly used sports lighting system (Halide) is inappropriate for this setting because it cannot achieve commonly recognized standards for residential neighborhoods. Musco noted, at the October 21st meeting, that “HID lighting cannot meet the parameters set" in earlier memoranda and that Musco had concluded were appropriate at this site. At the same meeting, Musco expressed concern about the appropriateness of LED lights at a height of 70’ or less because they “would deliver glare similar to HID lights.” More recently, during the field tests of ambient light, Musco representatives said that the company had determined that it could not recommend the use of LED lights on poles lower than 70’ and that such a caveat would be written prominently on their design documents. I recite this background to emphasize a point that is often obscured during our often detailed and frequently confusing examination of the Musco photometrics. Musco recognizes that this site is, indeed, very different than other sites in Arlington at which sports lighting has been installed. Indeed, Musco acknowledges that the only form of lighting that might conceivably achieve standards viewed as appropriate in the Williamsburg neighborhood is its newest generation of LED lights installed on poles that exceed, by nearly 20%, the maximum height for structures permissible under Arlington law. It’s important, I think, to review Musco’s most recent responses to our technical questions with that background in mind. The Working Group is trying, in good faith, to understand what the neighbors will experience in perpetuity if LED lights are installed on 80’ poles. During our last field visit, Musco representatives indicated that the company is taking the technical questions very seriously and has elevated those questions “to the highest levels of the company.” Musco’s responses can only be characterized as “minimalist,” however, and are not the kinds of responses the Working Group would expect to receive from the County’s sole source lighting contractor charged with helping County residents truly understand the effects of sports lighting on their quality of life. Rather, the responses are largely dismissive of the concerns raised, and serve principally to underscore the many uncertainties associated with lighting this site. Reflectivity: Concerns have been expressed, for some time, about the amount and direction of reflected glare, particularly given the very high levels of glare projected on the east side of the site. (As emphasized in the IESNA Recommended Practice for Sports and Recreation Lifhting (RP-6-01) “glare can be caused by the luminaries or indirectly from the reflection of surrounding structures within the field of view.”). Musco’s response is that reflected glare “is not within Musco’s control” and is not accounted for in the design. I was not asking, however, whether reflected glare was “within Musco’s control,” but rather whether it could be measured or estimated — since it’s an inevitable result of field lighting with high intensity LED lights. Musco also replied that “the LED source should be far less than 25000K if green space is present.” I don’t know how
to interpret this sentence, since the photometrics project 25000K on the east side of the site and there is no “green space” there — only school buildings. With respect to our question whether the elevated (25,000K candela) glare the east side of the site might be viewed as unusually high, Musco noted that “we have constructed lighting systems with similar off-site glare and glare will occur if green space is not present or elevations exist.” Again, it’s hard to know what is meant here. A more fulsome and frank response would address the neighbors’ anxiety about the very high glare levels from LED lights with some discussion of the rarity or commonplace nature of 25,000K glare and whether, in similar residential settings, County governments had approved lighting with similar effects. Musco concludes that glare will occur if green space is not present or elevations exist, but I’m not sure how those caveats apply here where there is no green space east of the site. I’m not sure what the phrase “elevation exists” means. Source/Background: I had suggested that perhaps Musco could generate a measure of glare using source/background contrast. I did so because others have noted that “glare experienced from high-intensity sources, like those used to light athletic fields, is the result of source to background contrast ratios.” Fairfax County, Athletic Field Lighting Technical Report. Musco has conducted a recent field visit to measure ambient levels and to compare those levels to expected spill. Musco’s response to my suggestion about generating a glare measure from ambient/source contrast is that such testing could not be conducted and that it “would need to use a developmental program to check glare.” I, for one, have no clue as to what this means, except that it seems unnecessarily dismissive. Health/Environmental Effects: As you both are aware, Working Group members have raised a number of questions about the potential health and environmental effects of blue-white LED lights. The lights currently proposed by Musco are 5700K, well above the 3000K color temperature necessary to receive the International Dark Sky Association’s (IDA) fixture seal of approval. The IDA provides objective, third-party certification for luminaires that minimize glare, reduce light trespass, and protect the nighttime sky. As the IDA has emphasized repeatedly, blue-white LED lights have been implicated in a host of adverse environmental and human health effects, including sleep disruption. (I have attached a recent letter from the IDA to the District of Columbia Department of Transportation objecting to the District’s plan to install LED street lights. That letter, written a year ago, summarizes briefly the IDA’s concern, and those of the American Medication Association’s Council on Science and Public Health, about human exposure to even low levels of blue-spectrum lighting). Musco asserts simply that there will be “no impact due to the duration of the lighted venue and the color of the surface being lit will filter out the blue light. Additionally, control of light eliminates light on adjacent properties.” Musco does not otherwise support these assertions and provides very little comfort to concerned neighbors and sports participants about long-term health and environmental effects from high-intensity LED lighting. We understand that Musco has had, or is having, discussions with the IDA regarding the appropriate temperature of LED lights. Musco cautions, however, that warmer lighting will require an increase in luminaires and thus increase light spill. Given the very low levels of light spill Musco is predicting with LED lights on 80’ poles, it is unclear to me whether this is a concern. Moreover, some investigators have noted that high temperature units “contribute more to light pollution on a per lumen basis than” low temperature units. Ian Ashdown, Color Temperature and Outdoor Lighting (July 2015). Because blue light is preferentially scattered, resulting in higher levels of light pollution, it might be speculated that warmer luminaires (even if greater numbers are needed) will result in less light spill. Moreover, the greatest issue with LED lights, as Musco would concede, is with glare. According to the IDA “outdoor lighting with high blue light content is more likely to contribute to light pollution because it has a significantly larger geographic reach than lighting with less blue light. Blue-rich white light sources are also
known to increase glare and compromise human vision, especially in the aging eye." IDA, LED Practical Guide. Pole Design and Placement: Since the luminaire aiming angles are critical to minimizing glare, we asked whether the proposed poles would conform to generally acceptable pole design requirements— i.e., the upper level of the defined beam would be no more than 80 degrees above nadir. Musco responded that the poles would achieve this standard provided that it “can still achieve a minimum aiming angle of 24 degrees down from horizontal.” I don’t understand this response. Is Musco saying that its ability to achieve the standard depends on pole height and that it will be able to achieve the standard with 80’ poles, or is it saying that compliance remains uncertain, even with higher poles? I understand that Musco has proposed locations for each of the 6 poles. Both IESNA and FIFA have developed standards for pole locations for soccer fields. The general aim of these standards is to prohibit the placement of poles near the mouth of the goals or near where corner kicks take place. To the untutored eye, pole S-4 appears to be very close to or within a prohibited glare zone. (IESNA, Recommended Practice for Sports and Recreational Lighting at 61, figure 81). Perhaps this is explains, in part, why the projected illumination on the field facing S-4 reaches 1.5 million candela (maintained candela per light bank)? Conclusion: There remain, at the very least, significant gaps in our understanding of the direct effects of the proposed lighting on residential quality of life, and in the long-term human and environmental effects of high intensity blue-white lighting. Given the state of the science, some of these gaps cannot, I suspect, be filled. As we move forward, it will be important for the Working Group to remember, that the neighborhood — and not the County — that will bear the costs of these uncertainties. (If you could distribute this to other members of the Working Group, I would be grateful. I still do not have a full list of e-mail addresses. Thanks very much). John Seymour
to interpret this sentence, since the photometrics project 25000K on the east side of the site and there is no “green space” there — only school buildings. With respect to our question whether the elevated (25,000K candela) glare the east side of the site might be viewed as unusually high, Musco noted that “we have constructed lighting systems with similar off-site glare and glare will occur if green space is not present or elevations exist.” Again, it’s hard to know what is meant here. A more fulsome and frank response would address the neighbors’ anxiety about the very high glare levels from LED lights with some discussion of the rarity or commonplace nature of 25,000K glare and whether, in similar residential settings, County governments had approved lighting with similar effects. Musco concludes that glare will occur if green space is not present or elevations exist, but I’m not sure how those caveats apply here where there is no green space east of the site. I’m not sure what the phrase “elevation exists” means. Source/Background: I had suggested that perhaps Musco could generate a measure of glare using source/background contrast. I did so because others have noted that “glare experienced from high-intensity sources, like those used to light athletic fields, is the result of source to background contrast ratios.” Fairfax County, Athletic Field Lighting Technical Report. Musco has conducted a recent field visit to measure ambient levels and to compare those levels to expected spill. Musco’s response to my suggestion about generating a glare measure from ambient/source contrast is that such testing could not be conducted and that it “would need to use a developmental program to check glare.” I, for one, have no clue as to what this means, except that it seems unnecessarily dismissive. Health/Environmental Effects: As you both are aware, Working Group members have raised a number of questions about the potential health and environmental effects of blue-white LED lights. The lights currently proposed by Musco are 5700K, well above the 3000K color temperature necessary to receive the International Dark Sky Association’s (IDA) fixture seal of approval. The IDA provides objective, third-party certification for luminaires that minimize glare, reduce light trespass, and protect the nighttime sky. As the IDA has emphasized repeatedly, blue-white LED lights have been implicated in a host of adverse environmental and human health effects, including sleep disruption. (I have attached a recent letter from the IDA to the District of Columbia Department of Transportation objecting to the District’s plan to install LED street lights. That letter, written a year ago, summarizes briefly the IDA’s concern, and those of the American Medication Association’s Council on Science and Public Health, about human exposure to even low levels of blue-spectrum lighting). Musco asserts simply that there will be “no impact due to the duration of the lighted venue and the color of the surface being lit will filter out the blue light. Additionally, control of light eliminates light on adjacent properties.” Musco does not otherwise support these assertions and provides very little comfort to concerned neighbors and sports participants about long-term health and environmental effects from high-intensity LED lighting. We understand that Musco has had, or is having, discussions with the IDA regarding the appropriate temperature of LED lights. Musco cautions, however, that warmer lighting will require an increase in luminaires and thus increase light spill. Given the very low levels of light spill Musco is predicting with LED lights on 80’ poles, it is unclear to me whether this is a concern. Moreover, some investigators have noted that high temperature units “contribute more to light pollution on a per lumen basis than” low temperature units. Ian Ashdown, Color Temperature and Outdoor Lighting (July 2015). Because blue light is preferentially scattered, resulting in higher levels of light pollution, it might be speculated that warmer luminaires (even if greater numbers are needed) will result in less light spill. Moreover, the greatest issue with LED lights, as Musco would concede, is with glare. According to the IDA “outdoor lighting with high blue light content is more likely to contribute to light pollution because it has a significantly larger geographic reach than lighting with less blue light. Blue-rich white light sources are also
known to increase glare and compromise human vision, especially in the aging eye." IDA, LED Practical Guide. Pole Design and Placement: Since the luminaire aiming angles are critical to minimizing glare, we asked whether the proposed poles would conform to generally acceptable pole design requirements— i.e., the upper level of the defined beam would be no more than 80 degrees above nadir. Musco responded that the poles would achieve this standard provided that it “can still achieve a minimum aiming angle of 24 degrees down from horizontal.” I don’t understand this response. Is Musco saying that its ability to achieve the standard depends on pole height and that it will be able to achieve the standard with 80’ poles, or is it saying that compliance remains uncertain, even with higher poles? I understand that Musco has proposed locations for each of the 6 poles. Both IESNA and FIFA have developed standards for pole locations for soccer fields. The general aim of these standards is to prohibit the placement of poles near the mouth of the goals or near where corner kicks take place. To the untutored eye, pole S-4 appears to be very close to or within a prohibited glare zone. (IESNA, Recommended Practice for Sports and Recreational Lighting at 61, figure 81). Perhaps this is explains, in part, why the projected illumination on the field facing S-4 reaches 1.5 million candela (maintained candela per light bank)? Conclusion: There remain, at the very least, significant gaps in our understanding of the direct effects of the proposed lighting on residential quality of life, and in the long-term human and environmental effects of high intensity blue-white lighting. Given the state of the science, some of these gaps cannot, I suspect, be filled. As we move forward, it will be important for the Working Group to remember, that the neighborhood — and not the County — that will bear the costs of these uncertainties. (If you could distribute this to other members of the Working Group, I would be grateful. I still do not have a full list of e-mail addresses. Thanks very much). John Seymour
