ID#2051 made on
SSc8 - Light pollution reduction
LEED BD+C: New Construction, LEED BD+C: Schools, LEED BD+C: Core and Shell
Because the criteria for Sustainable Sites Credit 8 have changed substantially from LEED-NC version 2.1 and version 2.2, this Credit Interpretation Request seeks guidance on whether CIRs issued for v2...
Because the criteria for Sustainable Sites Credit 8 have changed substantially from LEED-NC version 2.1 and version 2.2, this Credit Interpretation Request seeks guidance on whether CIRs issued for v2.1 would apply to similar situations under v2.2. The Tacoma Center for Urban Waters (TCUW) is a new 56,000 square foot office and laboratory building, located on the east side of the Thea Foss waterway in an area currently occupied by industrial uses. The ambient light level of this area is not high due to the fact that very little night use occurs. The TCUW will include facilities that are available to community groups and it is anticipated that a fair amount of after-hours use will take place. In addition, security for TCUW staff is a concern even during normal operating hours, as the Tacoma area experiences very short days during the winter months and it is anticipated that staff will arrive and leave in darkness for a significant part of the year. We have determined that the site qualifies as LZ3 - Medium (Commercial/Industrial, High-Density Residential) based on the current use of the surrounding area as well as the proposed use by TCUW. We would like to confirm that uplights which are shielded (i.e., located under an opaque canopy) would not count toward the percentage of allowable uplight under v2.2. We would also like to confirm that the principle outlined in the Columbia Heights CIR (12/1/2006) would apply to the TCUW project. The project includes a portion of the building that is set back from the property line by only 5 feet. The adjacent property is a narrow strip between our project and the city street that is used to park tanker trucks for the adjacent industrial uses. Our lighting of this area addresses two concerns. The first is security in this area, which does not receive any significant ambient lighting from surrounding properties or the street. Because views to the street are often blocked by parked trucks, the feeling of security in this area is very important. Also, the entire area between the building and the property line contains a sidewalk which also serves as path of egress to the public way. Our lighting scheme provides a maximum of 0.61 footcandles (fc) of horizontal illuminance and 1.0 fc of vertical illumination at the property line, which is also the curb line of the sidewalk. However, at 10 feet beyond the property line, light levels are 0.01 fc, with 0 fc at 15 feet beyond the property line. We have achieved this by utilizing a low-wattage (13 watt), wide-distribution fluorescent source, mounted at a low height (3.5 feet) on the building wall that adjoins the sidewalk. This fixture emits all light at angles below 90 degrees. All other components of the project comply with this credit, and we would like to confirm that our approach regarding the egress path lighting meets LEED's intent to reduce light pollution while allowing the project to meet code and security requirements.
1. Uplighting under an opaque canopy If the uplight is COMPLETELY contained under an opaque canopy, it does not have to be considered in the uplight tabulation. To document this, the team must show that a) the canopy is indeed completely opaque and b) that all angles where a candela value is emitted from the luminaire are blocked by the canopy. Provide a specification for the canopy material and a line diagram showing the canopy/luminaire geometry. If the luminaire is adjustable, the team must show that it will be locked in position or that the canopy will block the light at all possible aiming angles. 2. Egress Lighting The team's proposal of using very a low wattage fluorescent lamp in a fully shielded luminaire will meet the intent of the credit while still providing the egress light necessary to meet code. Applicable Internationally.
Related Addenda (Corrections & Interpretations)