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Project teams must comply with one of the two options for interior lighting AND the requirement for exterior lighting.See all forum discussions about this credit »
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Frequently asked questionsSee all forum discussions about this credit »
Can light trespass extend beyond the LEED Project Boundary if the adjacent land is owned by the project owner? Can projects use the actual property boundary/property line rather than the LEED Project Boundary (if the LEED Project Boundary is smaller than the property line) for the light trespass aspects of this credit? Can the lighting boundary be used in place of the LEED Project Boundary or site boundary for the purposes of this credit? When can the lighting boundary be modified? Can campus projects use the campus boundary for this credit? Do all SSc8 credit exterior requirements need to met at the lighting boundary? Does street lighting need to be included? How is the lighting zone determined when the project contains, or is adjacent to, a sensitive area?
All instances in the credit language of "LEED project boundary" or "site boundary" shall be considered to refer to the "lighting boundary", for the purposes of this credit only. The lighting boundary is located at the property lines of the property, or properties, that the LEED project occupies. The lighting boundary can be modified under the following conditions:-When the property line is adjacent to a public area that is a walkway, bikeway, plaza, or parking lot, the lighting boundary may be moved to 5 feet (1.5 meters) beyond the property line. -When the property line is adjacent to a public street, alley or transit corridor, the lighting boundary may be moved to the center line of that street, alley or corridor. -When there are additional properties owned by the same entity that are contiguous to the property, or properties, that the LEED project is within and have the same or higher lighting zone designation as the LEED project, the lighting boundary may be expanded to include those properties. If the LEED project boundary is smaller than the property line, projects can use the lighting boundary to meet the light trespass requirements of this credit. Buildings that are part of campuses or shared properties can use the "campus boundary", i.e. the campus property line, to comply with the light trespass requirements of this credit. All LEED projects attempting SSc8 should continue to meet all exterior requirements (LPD, uplight, trespass) based all of the exterior luminaries within the LEED project boundary. The lighting boundary is only for the purposes of the trespass calculation, based on the light emitted by the luminaires within the LEED project boundary. Project teams should take note that the LEED project boundary must be appropriately defined and comply with Minimum Program Requirement (MPR) #3- "Must be a reasonable site boundary". Street lighting that is required by governmental authorities to be installed within the LEED project, specifically for the purposes of lighting a public street, does not need to be included in any of the calculations. Project teams should provide documentation of the government requirement and a narrative describing the application of this exemption to the project. Determination of the appropriate lighting zone is critical for this credit. For properties that contain sensitive areas (such as sleeping units or species habitats), the project must meet the light trespass requirements at the boundary of the sensitive area. An area is considered sensitive if it has a lower lighting zone designation than adjacent areas. If there are any parcels within the property that have a lower lighting zone designation, the exterior lighting requirements must be met at the lighting boundary of those areas. Applicable Internationally.
***Update 1/1/13:This interpretation is written in an attempt to clarify the number of questions and ambiguities that exist around the \'lighting boundary\'. This interpretation supersedes LI 1622, LI 2342, LI 5272 and LI 10114
**Update 4/2/2014 strictly for Neighborhood Development projects:
Only the following portion of this ruling was made applicable to Neighborhood Development projects: "Street lighting that is required by governmental authorities to be installed within the LEED project, specifically for the purposes of lighting a public street, does not need to be included in any of the calculations. Project teams should provide documentation of the government requirement and a narrative describing the application of this exemption to the project."
The credit guidelines to limit light trespass created by the building and site lighting being confined to the property is appropriate for most situations, but is incompatible with the requirements of transitional traffic zones that enter and exit the property and therefore generally located on the property line for most applications. The lighting provided at the property line for road entrance and exit locations serves a variety of purposes, namely: 1. The property area for the road crossing location is an area of potential pedestrian-vehicle conflict. This area requires an appropriate level of illumination for the safety of the pedestrians and for clear visibility of vehicle operators. 2. The area in question is an intersection. Illuminating Engineering Society of North America (IESNA) RP 8 (Standard Practice for Roadway Lighting) recommends that the illumination levels at vehicle conflict locations be increased above similar recommended roadway lighting levels. 3. Vehicle traffic will require a minimal amount of transitional lighting when leaving or entering a lit roadway. Variations in illumination have detrimental effects to the driver that increase the potential for an accident. 4. Provides awareness of vehicle traffic outside of the property to potential inflow of new vehicles. The particular application of this credit interpretation concerns a hospital emergency centre located in a downtown area with high traffic and pedestrian volumes. The site includes a surface parking area for emergency response and public vehicle traffic responding to the emergency centre. Individuals entering the property will often be unfamiliar with the environment and will therefore require a degree of illumination that promotes an awareness of the surroundings allowing them to safely navigate the area. The lighting design for the facility takes into consideration recommended practices outlined in the LEED credit for reducing light pollution. All exterior luminaires are provided as full cut-off type with internal source shielding ensuring no direct illumination is provided above the horizontal plane to limit any spill lighting. With the exception of traffic conflict areas, the exterior lighting design has confined all illumination within the property boundaries. IESNA RP 8 item 3.6.2 states ".driveways serving high volume activities.should be illuminated similar to a major/major intersection." Item 3.6.4 states ".traffic conflict areas should be provided with illuminance values 50 percent higher than recommended for the street." Surrounding roadways would be classified as "collector" routes with "high" degrees of potential pedestrian conflict locations. Table 9 of IESNA RP 8 suggests that the average maintained illumination at the pavement level for this type of intersection be provided with 24.0/2.4 (lux/fc). This is significantly higher than the 6.0/0.6 (lux/fc) level requirement of LEED. The Lake Union District CIR (08/16/2003) addresses spill lighting from the property, but not specifically with respect to traffic intersection. The lighting levels provided at the traffic intersections located for our project design are provided more closely in compliance with IESNA RP 8 for recommended lighting levels at the traffic boundary locations. For our application, the spill lighting will be provided onto a roadway and no lighting will penetrate adjacent property windows. The levels dictated however are inadequate for the recommended lighting requirements of this application. For pedestrian safety, it is imperative to provide an appropriate level of illumination that meets the requirements of all involved. Without a re-evaluation of the lighting requirements of this credit, it will not be possible to provide for the recommended practice lighting levels for most projects at traffic congestion locations. It is requested that the LEED credit requirements allowing no light trespass at the property line be relaxed at traffic conflict locations and be more closely defined so as to allow the designer the ability to provide the appropriate lighting levels for these locations while meeting the intent of the credit.
The Lake Union District CIR (8/16/2003) was intended to light alleyways, not streets, and is not appropriate for this CIR. Because this site abuts a public right of way, the 6 lux (0.6 fc) requirement may be met relative to the curb line instead of the site boundary, and drop to 0.01 fc (0.1 lux) 15 feet past the curb line per LEED v2.2 SSc8 requirements. The determination of the lighting zone takes into account the nature of surrounding properties and sets the light trespass limit given the overall ambient brightness.***Update 1/1/13: LI 1622 has been superseded by LI 10236. 1622 is no longer valid.
Can projects use the actual Property Boundary/ Property Line rather than the LEED Project Boundary (if the LEED Project Boundary is smaller than the Property Line) for the light trespass aspects of this credit? If so, are other aspects of exterior lighting (covered by this credit) to be evaluated relative to the LEED Project Boundary or Property Line if a project elects to use the Property line rather than the LEED Project Boundary for trespass criteria?
If the LEED Project Boundary is smaller than the property line, projects can use the property line (property boundary) of their property to meet the requirements of this credit. If the light trespass requirements are met at the property line, the other aspects of the exterior lighting requirements must also be met at the property line.For properties that contain sensitive areas (such as sleeping units or species habitats), the project must meet the exterior lighting requirements at the boundary of the sensitive area. An area is considered sensitive if it has a lower lighting zone designation than adjacent areas. If there are any parcels within the property that have a lower lighting zone designation, the exterior lighting requirements must be met at the lighting boundary of those areas.Definition of "Lighting boundary": the lighting boundary is located at the property line or boundary of the LEED project. This boundary may be expanded to include any additional properties owned by the same entity that are (1) contiguous to the project property and (2) have the same or higher Model Lighting Ordinance Lighting Zone designation as the LEED project.Exceptions: When the property line abuts a public area that is a walkway, bikeway, plaza, or parking lot, the lighting boundary extends to 5 feet beyond the property line; When the property line abuts a public roadway or public transit corridor, the lighting boundary extends to the centerline of that roadway or corridor. Applicable Internationally***Update 1/1/13: LI 10114 has been superseded by LI 10236. 10114 is no longer valid.
Does a reduction in the total LPD for exterior lighting warrant an exemption from the reduced uplighting requirements?
The exterior lighting power density (LPD) and uplighting requirements for SSc8 should be met in their entirety. In order to achieve the credit, project teams should comply with the LPD and the uplighting requirements independently. Substantial reduction in the percentage of total allowable LPD for exterior lighting does not compensate for, or warrant, an exemption from the reduced uplighting requirement for each zone. The purpose of reducing the uplight is to limit the amount of light emitted at an angle of 90 degrees or higher from nadir (straight down). Applicable Internationally.
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Project teams must comply with one of the two options for interior lighting AND the requirement for exterior lighting.