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HomeMy WebLinkAboutAgenda 09_LNC FedEx Lighting Review FINAL_2019-09-17_memo only 1 September 17, 2019 Marla Keene, PE Development Review Planner City of South Burlington 575 Dorset Street South Burlington, VT 05403 Fed-Ex Site Lighting Design Review L.N. Consulting, Inc. (LNC) has been retained to review the lighting design package, dated September 4, 2019, for the exterior lighting at the Fed-Ex building located at Technology Park, South Burlington. The lighting design package included a submittal package for the light fixtures being used as well as a lighting design photometric plan for the site. The lighting design package was provided by the Charron Inc., a lighting and lighting control system supplier based in Manchester, NH. The LNC review will be based on the South Burlington Land Development Regulations (LDR), Section 13.07 Exterior Lighting, adopted August 6, 2018. The report will also reference relevant requirements for ACT 250 regarding exterior lighting as well as any input from the City of South Burlington Development Review Planner. The report will indicate where the design does or does not meet the requirements above as interpreted by L.N. Consulting. Where the regulations have not been met, the report will provide recommendations to meet the standards. The report will also indicate any conditions that, although may meet the technical requirements of the LDR standards, should be evaluated further. The site will be considered Mixed I/C zoning district as defined by South Burlington. Per LDR Appendix A.9 Direct Glare on page 310, luminaires shall not be placed more than thirty feet (30’) above ground level and the maximum illumination at ground level shall not be in excess of an average of three (3) foot candles. The highest poles are set at 27’-6” so it is understood the luminaire will not be above 30’. Based on the lighting design shown on drawing “Lighting_Plan.2019-09-04.pdf” furnished with the design package, there are instances where the peak foot candles are above 3 in the west parking. However it appears the average for this parking lot will be lower than 3 and will meet the LDR requirement. For the drive way around the Fed-Ex building itself, it does appear that the average foot candles within the driveway and perimeter of the Fed-Ex building may be above 3 foot candles. Most of the higher foot candle readings occur along the outside of the building on the north and east sides. This may be due to the significant number of WM6-2 wall mounted fixtures; mounted 15’ above grade, as well as the high wattage SG1 fixtures mounted 25’ above grade. Per the lighting plan it appears the WM6-2 fixtures along north and northeast side of building are approximately 12’ apart. It appears this lighting is for the sidewalk around the building. It is recommended that the layout of the WM6-2 be re-evaluated to see if the number of these fixtures can be reduced by spreading them further apart. Along the south side of the building the footcandle readings are generally lower than the north and west, however it appears these may still be slightly above an average of 3 foot candles. It is recommended evaluating replacing the SG1 fixtures with WM4 (possibly higher wattage version of the WM4) which may reduce some of these foot candle values. It may also delete the need for flood lights and their potential glare impacts. 2 It is unclear why the west side of the building has a much lower foot candle output than the rest of the areas around the building. Based strictly on the lighting plan provided it would be assumed the west area should be similar to the other areas. This lower light level should not be used to “average” the total light level around the building to below 3 foot candles. Per the lighting plan the mounting heights are approximately 15’ for the WM4 and WM5 fixtures, with the SG1 and WS4 fixtures mounted at 25’. Both are lower than the 30’ limit. The distance from the parking lot lights to the Interstate right of way appears to be approximately 160’. The distance between the right of way and the actual highway is another 100’. Based on the lighting plan the highest foot candle reading at any property line indicated is 0.2 foot candles, with most locations less than that. None of the fixtures shines light upwards and it is understood the SG1-R flood lights with hoods could be aimed such that the maximum output is less than 60° from grade level, though the applicant has not specified the angle at which they will be aimed. This would be required to meet the indirect glare requirements of LDR Appendix A.10 Indirect Glare. Under LDR 13.07 B (1), there is a comment indicating “evenly distributed” lighting if fixtures are placed “at intervals equal to four times mounting height”. With new LED technology and the ability to specify specific light distribution patterns, this is no longer necessarily the case. Depending on where used, the light fixtures in the lighting package have specific lighting distribution patterns that best meet the location. For instance, the S5 poles in the middle of the parking lot shine in all directions (“Type 5 square”) to light up all areas around the pole. In contrast, the S3 poles use a “Type 3” distribution that instead spreads in an “east/west” pattern with less light in front and, with backlight “spill control”, even less behind the fixture. This last feature helps prevent light from “spilling” into areas behind the parking lot that may trespass into adjacent properties. So in general, along a driveway the Type 3 fixtures are used so the fixtures can be further apart than a Type 5 could be. Other than the concern that the foot candles may be higher than necessary around the perimeter of the building, the foot candle levels elsewhere seem to meet the values indicated in the LDR. Having said that, the average light levels within the parking lot and driveway appear higher than those recommended by IES (Illuminating Engineering Society). This may be due to the need for higher light levels required for operations. The light levels at the northeast and southeast corners (S4 fixtures) seem higher than necessary so would recommend reviewing those. As mentioned above, the remaining driveway around the building may be slightly high is some cases. It may make sense for the lighting designer to look into “trimming” the output of some of these fixtures (whether via programmed dimming or other method) to bring these levels more in line with the 3 foot candle average and light levels recommended by IES. Although the lighting design technically meets the LDR requirements for direct and indirect glare, a concern is the relatively high glare ratings for some of the higher wattage fixtures. The “B.U.G.” ratings are developed by IES (Illuminating Engineering Society) and indicate supposed “backlight”, “uplight” and “glare” for that specific fixture. All of these are what would be called “useless” light. All the fixtures appear to have a “U0” rating, indicating no uplight. However, since some of the fixtures are of such a high lumen output fixture, the backlight (B) and glare (G) ratings are higher than desirable. For the S3 fixture, the ratings are B3 and G4. The maximum is 5. Because the distance of these fixtures to adjacent properties is so far, this may 3 not be an issue. However typically anything above a 3 is not desirable is a mixed occupancy zone. Although somewhat complicated to calculate, the “glare” rating is based on the amount of lumens given off from the fixture between 60 and 80 degrees from grade. A lumen per square foot equals foot candles. A G4 rating is a minimum of 7,500 lumens and as high as 12,000 lumens. These are fairly high numbers. Although the percentage of this glare light output compared to total light output may be small, because the total light output is high the glare lighting output also ends up high. Other than the possibility of finding another fixture type with a rating lower than B3 and G4, providing lower wattage fixtures may be required. This may however also result in lower height poles and subsequently more poles. A similar glare concern may be associated with the use of flood lights. The SG1 fixtures are flood lights with an uplight protector to prevent light from shining upwards. However, being flood lights the light source may be visible from a significant distance since it is pointed near horizontally and not downwards. This may have an impact on locations outside the site. These fixtures will be facing towards Interstate 89. Although the SG1 submittal sheet says “Dark Sky Friendly with Zero Upward Light”, there is no “BUG” rating nor is it apparent what the glare impact may be. It is also not known how these light fixtures are being aimed in the analysis, although per the LDR they need to be aimed such that the maximum foot candles are shielded above 60 degree from the ground. It is therefore recommended the lighting designer provide an analysis of the impact on glare and how the lights will be aimed. This may involve taking into account the height of the pole “above or below” the elevation of areas around the site, such as Interstate 89. Because the flood lights shine at a slightly downward slope from horizontal, there may also be issues with reflection off vehicles or cars, or even snow. For many of these reasons the use of flood lighting is typically frowned upon. A recommended alternative would be to investigating replacing the SG1 flood lights with more of the WM4-type wall mount fixtures. This may also reduce the average foot candle levels. It appears the pole mounted lighting comes with a dimmable output. It is not clear how the lights are controlled and if they can or will be dimmed. The wall mounted lighting appears to not be providing with dimming capability. It would be recommended that some form of motion sensing by provided with the fixtures that could shut off or dim light fixtures when no motion sensed. This would be in addition to any other controls, whether integral to the fixture or via a remote control system. Reducing light output, particularly when the facility’s site does not need to be fully lit at night, would help alleviate some concerns. ACT 250 may have some additional requirements, not least of which is meeting the requirements of the VT Commercial Building Energy Standards per Table C405.5.5(2). The lighting zone should be verified with South Burlington however it appears the site would be considered Zone 3 per the table. These requirements would typically need to be confirmed to be met. 4 The above report is L.N. Consulting’s interpretation of the design and regulations as well as our opinion based on our lighting experience. Please feel free to contact us if you have any questions or comments. Sincerely, John Askew, P.E. L.N. Consulting, Inc. Attachments: Lighting_Plan_2019-09-04.pdf FEDEX Ext. Lgt Submittals (BURLINGTON VT).pdf LDR Lighting Excerpt.pdf