Our project is located in the Lake Union District of Seattle, Washington and falls under the lighting category \'High Ambient Brightness.\' The project comprises a five-story building on a 0.58 acre site. The building is bordered by city streets and sidewalks, which are not part of our project site.All exterior lighting complies with the referenced IESNA Practice Manual for Exterior Environments. All interior and exterior lighting is designed such that "zero direct-beam illumination leaves the building site" with the following exception.The building directly abuts the site boundary (city sidewalks in front and alley way in back). As a result, the exterior light fixtures will direct some light onto this adjacent sidewalks and alley way. The current alley way has no exterior lighting. Please confirm that we comply with the intent of SS8 to eliminate light trespass from the building site.
As was stated in the 7/21/2003 Project ManagerÆs Rulingà ôTable 1 on page 70 of the LEED v2.1 Reference Guide, which is adapted from the referenced standard (IESNA RP-33-99), describes light trespass limitations for four distinct environmental zones.ö If in fact your project falls within the Environmental Zone E4 Areas of high ambient brightness, then the limitation for light trespass onto adjacent properties is 6 lux (0.6 fc). As illustrated in the example contained on page 75 of the LEED v2.1 Reference Guide, the ôline of site illuminanceö must be calculated for the adjacent luminaire. Since, from your description, it appears that any illuminance will trespass onto another property, additional information must be provided. Include detailed calculations and drawings similar to those on page 75 of the LEED v2.1 Reference Guide, showing that no direct beam illumination will enter any windows of any adjacent properties and that the light trespass is limited to 0.6fc at the window locations. If it is determined that the light trespass is greater than allowable, then the credit is not attainable.