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LEED v2009
Existing Building Operations
Sustainable Sites
Light Pollution Reduction

LEED CREDIT

EBOM-2009 SSc8: Light Pollution Reduction 1 point

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Requirements

Project teams must comply with the interior lighting requirement AND 1 of the 3 options for exterior lighting.

For interior lighting
All nonemergency built-in luminaires with a direct line of sight to any openings in the envelope (translucent or transparent, wall or ceiling) must be automatically controlled to turn off during all after-hours periods during the performance period. The total duration of all programmed after-hours periods annually must equal or exceed 2,190 hours per year (50% of annual nighttime hours). Manual override capability may be provided for occasional after-hours use. Implement a program to ensure that the lighting control system is being properly used to adjust lighting levels during all after-hours periods.

For exterior lighting

Option 1
If the project is certified under LEED for Schools or New Construction, show that SS Credit 8: Light Pollution Reduction was earned. If the project is certified under LEED for Core & Shell Development and 75% of the floor area is LEED for Commercial Interiors, show that SS Credit 8: Light Pollution Reduction was earned for both systems.

OR

Option 2
Partially1 or fully shield2 all exterior fixtures 50 watts and over so that they do not directly emit light to the night sky.
Option 3
Measure the night illumination levels at regularly spaced points around the perimeter of the property, taking the measurements with the building’s exterior and site lights both on and off. The building’s interior lights must be in the same state during both measurements. At least 8 measurements are required at a maximum spacing of 100 feet apart (30 meters), so as to be representative of the illumination levels at the perimeter of the property. The illumination level measured with the lights on must not be more than 20% above the level measured with the lights off. This requirement must be met for each measurement point; averaging of all points is prohibited.
1The requirement to use ASHRAE Addenda is unique to this credit and does not obligate Project teams to use ASHRAE approved addenda for other credits. 2 To be LZ4, the area must be so designated by an organizations with local jurisdiction, such as the local zoning authority.

Alternative Compliance Paths (ACPs)

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Frequently asked questions

Are we required to include city-owned and controlled lighting with our exterior lighting fixtures?

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We’re pursuing Option 3 for exterior lighting and the difference in illumination is greater than 20% so we don’t comply. In this case, can we pursue the illumination requirements for the applicable lighting zone (similar to LEED-NC)? For example if we’re in LZ4 and the illuminance at the site boundary is less than 0.6 fc can we comply that way?

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If we have exterior lighting fixtures over 50 watts with occupancy sensors, can these fixtures be excluded from the shielding requirements of Option 2?

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How do you treat lighting in the covered portion of an exterior parking garage? Do you follow the interior lighting requirements or the exterior lighting requirements?

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Addenda

8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
See revised image
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the second to last sentence to read, "Finally, measure the angle between this fixture line of sight and the perpendicular with the vertex located at the fixture edge."
Campus Applicable
No
Internationally Applicable:
No
12/18/2007
LEED Interpretation
Inquiry:

The project is a four level public parking ramp that is an independent building from but serves several floors of condominiums and a 24 hour operated casino, which makes the parking ramp a 24 hour occupied structure. There are no exterior walls on the ramp with the exception of floor to ceiling structural columns on a 24\' by 56\' grid. The fixtures are mounted at 11\' above the finished floor and placed within 10\' of the edge of the decks with a glare shield to reduce light spill out from the ramp. The LEED interior lighting requirements state that "The angle of maximum candela for each interior luminaire as located in the building shall intersect opaque building interior surfaces and not exit out through the windows." We have no windows on the parking structure and no other way to prevent light from escaping from the structure on the sides where it does not directly abut another building. We are asking for an interpretation as to whether this is considered an interior or an exterior lighting application? A ruling will help us determine if we will be able to pursue a LEED credit for light pollution reduction on this project.

Ruling:

The applicant is seeking clarification as to the interior/exterior area classification for a four level open air parking ramp building. For the purposes of SSc8, parking structure covered floor area is to be considered interior area and uncovered area is to be considered exterior area. Thus, any lighting within covered area must meet the interior lighting requirements of this credit and any lighting within uncovered area must meet the exterior lighting requirements of this credit, including being below specified foot candles horizontal and vertical at all locations outside the boundary of the property. For the purposes of clarity, the credit requirements pertaining to interior luminaires\' angle of maximum candela not exiting out windows also requires that interior luminaires\' angle of maximum candela not exit out building openings or other translucent surfaces. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
1/24/2005
LEED Interpretation
Inquiry:

Our project is located at the instersection of two Class 1 Pedestrian Streets in Downtown Seattle. The neighborhood is zoned Downtown Mixed Commercial, allowing for a variety of uses. The project is an 11 story Research and Development facility programmed as operable 24 hours per day. Immediate neighbors include the Greyhound Bus Terminal, The West Precinct Seattle police Department Headquarters, Qwest Communications and, dirctly across the Street, surface parking. These are all active 24 hour operations and contribute to the neighborhood\'s high ambient light level. Considering these factors we have selected lighting for the building which maintains safety for pedestrians while being uniform and understated. along the alley deep shielded Ruud E8-F fixtures are installed at 8\' above the pavement at egress and service doors. On the two street facades at sidewalks, we have utilized Bega 7475MH surface washers mounted at 10\' - 12\' above the walking surface and aimed at the underside of the translucent overhead protection canopies. This provides an even wash of indirect light to the pedestrian walking surface while eliminating the escape of direct light. The fourth side of the building is against the adjacent structure and has no lighting. Three parking levels above street level have cut-off fixtures installed 20\' or more from the exterior walls, further shielded by aluminum screening at the exterior openings to the garage. Lobby lighting is limited to recessed cans, recessesed track and diffuse light from an internally lit large glass sculpture.Our project replaces a surface parking lot that included two unshielded pole area-lights and two 2-sided illuminated billboards. Light level measurements were not taken when these elements were operational so comparative data is not available.I feel that we have responded to both the neighborhood and the credit although the light trespass onto the alley and sidewalks ranges from 2 to 10 footcandles. However, the light trespass onto "adjacent properties" is less than 0.6 footcandles (or 6 lux).I would appreciate your view on this particular situation.

Ruling:

There are multiple components of this CIR that are addressed in the five points below.1. Pedestrian Indirect Lighting: Pages 71 & 72 of the LEED-NC v2.1 Reference Guide discusses design approach strategies to comply with the intent of Sustainable Sites Credit 8. The Guide states "In areas of high ambient brightness, some low level (subtle) lighting of features, facades or landscape areas may be appropriate in pedestrian environments or for identification and way finding" Uplighting a translucent canopy that is continuous around two facades of the building is not consistent with the intent of this credit.To be more consistent with the credit intent, the following steps may help achieve SSc8: (a) Limit uplighting the translucent canopy to key focal points such as main entrances or use opaque material for the continuous canopies. Also, for uplighted areas, provide information about the translucent canopy, showing that the transmittance of the canopy has been minimized. (b) Show that the light distribution is limited to the canopy and does not spill beyond. To help clarify the design, provide a section showing the relationship of the luminaire to the canopy, showing that the photometric distribution from the luminaire is entirely captured by the canopy. (c) Specify a lamp package that has 3500 initial lumens or less. The standard lamp for the Bega 7475MH is a 70 watt metal halide with 6400 initial lumens, which will not meet the credit requirement. (d) Specify a luminaire that has a fixed, non-adjustable mounting. The Bega 7475MH is an adjustable luminaire that would allow changing of the intended aiming after the installation is complete, and refer to item (b).2. Alley Lighting: It is not clear that the Ruud E8-F luminaire meets IESNA Full Cut-off classification, therefore the lamp package must be 3500 initial lumens or less to comply with this credit, or supply documentation showing that the luminaire meets the full cutoff requirements.3. Light Trespass to Alley and Sidewalk: 2 - 10 footcandles far exceeds the limitation of 0.6 as stated in Table 1 on page 70 of the LEED-NC v2.1 Reference Guide. Refer to SSc8 LEED Interpretation Inquiry #5409 (request date 8/16/2003, ruling date 9/2/2003). Include detailed calculations and drawings similar to those on page 75 of the Reference Guide, showing (a) that the light trespass limitation of 0.6 is met at the curb line of the sidewalk of the 2 street sides and (b) 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 in the alley.4. Parking Garage Lighting: For all levels of the parking garage, show that the peak candela of the luminaires falls within the parking garage. If the top level of the parking garage is open to the sky, provide luminaire cutsheets showing that they meet IESNA full cut-off classification, and meet all other exterior requirements.5. Lobby Lighting: From the description provided, the lighting in the lobby satisfies the requirements of SSc8. Provide a diagram and photometric distributions of luminaires showing that the peak candela falls within the building. Note: all other interior lighting must also meet the requirement that the peak candela falls within the building.

Campus Applicable
No
Internationally Applicable:
No
1/1/2014
LEED Interpretation
Inquiry:

After performing illumination measurement readings, some measurements exceeded the threshold dictated by Option 3, Approach 1: Difference in Illumination levels is 20 percent or less. The uncertainty of the light meter used is over six times the captured light level, which could be a result of the inability of a calibrated meter to obtain accurate readings due to low light levels on the project. Even though some measurements exceed the Option 3 threshold, we feel that the project's low light levels meet the intent of the credit. Can readings that are exceeded by the uncertainty of a calibrated light meter be excluded from Option 3?

Ruling:

The proposed strategy of excluding readings that are exceeded by the light meter uncertainty is not acceptable for SSc8 Light Pollution Reduction. Due to the calculation method of the uncertainty of the light meter, in low light situations where the difference in readings with the exterior lights on and off is less than the uncertainty of the meter this would apply to a far greater number of data points than those with minimal differences in lighting.

As an alternative, projects may demonstrate that measurement points meet the values listed in New Construction SSc8 Light Pollution Reduction for the project’s lighting zone. A combination of strategies is allowed, however each measurement point must comply with one of the strategies, with no exceptions or averaging across data points.

Campus Applicable
Yes
Internationally Applicable:
Yes
5/9/2011
LEED Interpretation
Inquiry:

Can projects uplight a single flagpole, as previously allowed under NC 2.1?

Ruling:

While it is correctly pointed out that previous CIRs have addressed this issue for LEED-NC v2.1, it should be noted that due to the changes to how sky glow concerns are now addressed by this credit, the old CIR is not applicable to LEED 2009 projects. Therefore, uplighting a flag is permissible provided that the credit requirements (including that the total percentage of light emitted above 90 degrees from nadir is within the allowable threshold relative to the declared environmental zone) are met.It should further be noted that there are many manufacturers of flagpole downlighting. It is recommended that the project team work with an exterior lighting designer to identify additional options.Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:

Can multifamily projects be exempt from the interior lighting requirements?

Ruling:

Yes, multifamily LEED projects are exempt from the Interior Lighting requirements of this credit. Residential spaces (dwelling units only) within the scope of other LEED projects are also exempt from the Interior Lighting requirements. Item #3 in LEED Interpretation #5149 ("[3] Residential spaces may not be exempted from the interior lighting requirements.") is now void.

Campus Applicable
No
Internationally Applicable:
No
6/1/2009
LEED Interpretation
Inquiry:

We currently have accent lightings that are not fully shielded accenting statues on the crown of our building. These lights are turned on for an average of six hours per night, fluctuating depending on the time of year. The current lights are 120W halogen bulbs. Per the reference guide, these would have to be fully shielded if we were to qualify for SS 8. We are proposing a project to remove these lights and replace them with dramatically more efficient LED lights that will be well under 50W, reducing the energy usage by an estimated 500%. We want to confirm the exclusion in Option B relating to fully shielded fixtures listed for 50W and under exterior lights on page 108 in the reference guide to make sure we are eligible for SS 8 on this project. By doing this, all exterior lights above 50W will be shielded and we will have a marquee project utilizing a new technology that will be presented to the building tenants as part of a tenant education program highlighting our sustainable technology.

Ruling:

Fixtures less than 50 watts are excluded from the shielding requirements for EB O&M SSc8 Exterior and Site Lighting Option B. Buildings with no exterior or site lighting fixtures at 50 watts or more would also meet the requirements for SSc8 Option B. This project would be eligible for EB SSc8 Option B only if the unshielded accent lights were completely replaced by LED fixtures that are less than 50 watts before the start of the performance period and SSc8 interior lighting criteria were met as well. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
3/14/2003
LEED Interpretation
Inquiry:

Our project is located in the heart of downtown Allentown PA and falls under the lighting category "High Ambient Brightness." The site comprises an eight storey building, approximately 140 in height above grade, and a plaza in front of that building. The plaza is bordered by city streets and sidewalks (not part of our project site), with city standard historic pole mounted fixtures. These fixtures are not cutoff fixtures and distribute light in a radial pattern towards the street, the sidewalk below, and towards the plaza. Our project\'s landscape lighting scheme is designed to balance the perceived brightness from these city street lighting fixtures by utilizing up-lit trees within the plaza as glowing objects that replace the need for additional pole mounted fixtures. Additionally, the plaza incorporates a fountain with up-lit water jets to enliven the plaza at night and add to the perception of the plaza as an occupied public space. Aside from the trees and fountain, all other plaza lighting, and the light levels eminating from the adjacent internally lit 140\' high building, are clearly within proscribed low-level light standards proscribed by the LEED 2.0 Rating System and its associated credit inquiries. We would like the USGBC to confirm that the up-lighting scheme for these plaza trees and fountain conforms to the revised lighting requirements specified in the LEED 2.1 Rating System and thus the general intent of this credit to eliminate light trespass, improve night sky access, and maintain a safe and appropriately lit urban public space.Beginning with the trees, which are the primary lighting component of the plaza, they are nominally 16\' to the top of the canopy. The illuminated undersides of the canopy at this pedestrian scale would significantly contribute to the public perception of a safe environment. Based on detailed computer modeling of the proposed tree lighting scheme, we find an average light level of 2.0 fc directly above the tree canopy when lit from below by the specified recessed up-lighting fixtures. As an additional note, the source is regressed within the fixture suspended from a cast iron tree grate cross louver providing superior cut off shielding of the source. Based on the foot candle levels above the tree canopy, and especially when put in the context of the adjacent street lights and the neighboring tall building, the lighting of these trees meets IESNA standards for low level exterior lighting and we believe that there is effectively no stray light adversely affecting this urban setting.The second area of up lighting in the plaza is the fountain, which comprises water jets that are lit from below by parabolic luminaries. The light fixtures are provided power only when the fountain pumps are active, so there would be no circumstance in which the lights would operate without a water column above the lamp to shield the light source. The effectiveness of the water as a light shield was determined in a measured study of the fountain light levels, which recorded an average light level of 9.06 fc three feet above the water feature when utilizing a 50W MR16 source. The design calls for a 35W lamp instead, which should reduce the measured average light level above the fountain to approximately 6fc. As a note, the luminaires are less than 3500 lumens and do not require full cutoff shielding; because each fixture is recessed well below the level of the paving, the full intensity of a lamp would never be visible since there will always be a column of water atop it. Accordingly, we believe the fountain lighting levels are well within the IESNA standards, especially as the fountain is located between the unshielded city street lights and the 140\' high illuminated building.Please confirm that these two plaza elements with their carefully shielded up-lit elements meet both the specific requirements of LEED 2.1 SS credit 8, and the larger intent "to provide enough illumination for safety, accessibility and public perception while at the same time avoiding unnecessary light pollution."

Ruling:

Under LEED v2.0, uplights are precluded in achieving this credit, as they represent direct beam illumination to the night sky. Under LEED v2.1, clarifications have been made that allow some limited uplighting, primarily for the purposes of lighting the American flag at night.In areas of high ambient brightness only, limited uplighting will be allowed if the following conditions are met: (1) All credit requirements are met, including full cut off luminaires for lamps over 3500 initial lumens and shielding for those over 1000 initial lumens. (2) Lighting controls are used to turn off lighting after hours and/or during post curfew periods. A plan should be developed to insure the use of the controls (automated controls, etc.). Note that some landscape features such as trees and plants (depending somewhat on the type of planting) require a rest from light. (3) Lighting controls are commissioned.In addition to the above conditions (and associated documentation), certain additional information must be provided to demonstrate compliance with the credit intent: (1) The results of a light study that verifies the illumination intensity emitted directly above the feature being lit (in this case, the fountains and the trees). (1a) If trees are being uplit, this study must verify the maximum light levels that will be produced when the trees have dropped all of their leaves. (2) A narrative describing how light levels and glare will be controlled around the trees in each of the seasons and listing the hours of intended uplighting operation for both the water feature and the plaza tree lighting. (3) A statement from your landscape architect indicating that the planned tree lighting will not have adverse effects on the trees\' dormancy cycles. (4) Confirmation that the fixtures and lamps installed are the same as those modeled.Note: the v2.1 Reference Guide language will provide further clarifications; please refer to that document before finalizing your design.

Campus Applicable
No
Internationally Applicable:
No
1/1/2015
LEED Interpretation
Inquiry:

Is there another way for Existing Building projects to meet the interior lighting requirements?

Ruling:

**Updated 7/1/2015 to clarify compliance paths.
Existing Building projects, including spaces that operate 24/7, can demonstrate compliance by following Option 2 in New Construction:

Option 2
All openings in the envelope (translucent or transparent) with a direct line of sight to any non-emergency luminaires must have shielding (controlled/closed by automatic device for a resultant transmittance of less than 10% between 11 p.m. and 5 a.m.).

This interpretation is not applicable to v4 projects because there are no interior lighting requirements in v4.

Campus Applicable
Yes
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

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?

Ruling:

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.

Campus Applicable
No
Internationally Applicable:
Yes
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Sr. Electrical Engineer

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Requirements

Project teams must comply with the interior lighting requirement AND 1 of the 3 options for exterior lighting.

For interior lighting
All nonemergency built-in luminaires with a direct line of sight to any openings in the envelope (translucent or transparent, wall or ceiling) must be automatically controlled to turn off during all after-hours periods during the performance period. The total duration of all programmed after-hours periods annually must equal or exceed 2,190 hours per year (50% of annual nighttime hours). Manual override capability may be provided for occasional after-hours use. Implement a program to ensure that the lighting control system is being properly used to adjust lighting levels during all after-hours periods.

For exterior lighting

Option 1
If the project is certified under LEED for Schools or New Construction, show that SS Credit 8: Light Pollution Reduction was earned. If the project is certified under LEED for Core & Shell Development and 75% of the floor area is LEED for Commercial Interiors, show that SS Credit 8: Light Pollution Reduction was earned for both systems.

OR

Option 2
Partially1 or fully shield2 all exterior fixtures 50 watts and over so that they do not directly emit light to the night sky.
Option 3
Measure the night illumination levels at regularly spaced points around the perimeter of the property, taking the measurements with the building’s exterior and site lights both on and off. The building’s interior lights must be in the same state during both measurements. At least 8 measurements are required at a maximum spacing of 100 feet apart (30 meters), so as to be representative of the illumination levels at the perimeter of the property. The illumination level measured with the lights on must not be more than 20% above the level measured with the lights off. This requirement must be met for each measurement point; averaging of all points is prohibited.
1The requirement to use ASHRAE Addenda is unique to this credit and does not obligate Project teams to use ASHRAE approved addenda for other credits. 2 To be LZ4, the area must be so designated by an organizations with local jurisdiction, such as the local zoning authority.

Alternative Compliance Paths (ACPs)

[view:embed_resource=page_1=4649824]

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Are we required to include city-owned and controlled lighting with our exterior lighting fixtures?

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We’re pursuing Option 3 for exterior lighting and the difference in illumination is greater than 20% so we don’t comply. In this case, can we pursue the illumination requirements for the applicable lighting zone (similar to LEED-NC)? For example if we’re in LZ4 and the illuminance at the site boundary is less than 0.6 fc can we comply that way?

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If we have exterior lighting fixtures over 50 watts with occupancy sensors, can these fixtures be excluded from the shielding requirements of Option 2?

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How do you treat lighting in the covered portion of an exterior parking garage? Do you follow the interior lighting requirements or the exterior lighting requirements?

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8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
See revised image
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the second to last sentence to read, "Finally, measure the angle between this fixture line of sight and the perpendicular with the vertex located at the fixture edge."
Campus Applicable
No
Internationally Applicable:
No
12/18/2007
LEED Interpretation
Inquiry:

The project is a four level public parking ramp that is an independent building from but serves several floors of condominiums and a 24 hour operated casino, which makes the parking ramp a 24 hour occupied structure. There are no exterior walls on the ramp with the exception of floor to ceiling structural columns on a 24\' by 56\' grid. The fixtures are mounted at 11\' above the finished floor and placed within 10\' of the edge of the decks with a glare shield to reduce light spill out from the ramp. The LEED interior lighting requirements state that "The angle of maximum candela for each interior luminaire as located in the building shall intersect opaque building interior surfaces and not exit out through the windows." We have no windows on the parking structure and no other way to prevent light from escaping from the structure on the sides where it does not directly abut another building. We are asking for an interpretation as to whether this is considered an interior or an exterior lighting application? A ruling will help us determine if we will be able to pursue a LEED credit for light pollution reduction on this project.

Ruling:

The applicant is seeking clarification as to the interior/exterior area classification for a four level open air parking ramp building. For the purposes of SSc8, parking structure covered floor area is to be considered interior area and uncovered area is to be considered exterior area. Thus, any lighting within covered area must meet the interior lighting requirements of this credit and any lighting within uncovered area must meet the exterior lighting requirements of this credit, including being below specified foot candles horizontal and vertical at all locations outside the boundary of the property. For the purposes of clarity, the credit requirements pertaining to interior luminaires\' angle of maximum candela not exiting out windows also requires that interior luminaires\' angle of maximum candela not exit out building openings or other translucent surfaces. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
1/24/2005
LEED Interpretation
Inquiry:

Our project is located at the instersection of two Class 1 Pedestrian Streets in Downtown Seattle. The neighborhood is zoned Downtown Mixed Commercial, allowing for a variety of uses. The project is an 11 story Research and Development facility programmed as operable 24 hours per day. Immediate neighbors include the Greyhound Bus Terminal, The West Precinct Seattle police Department Headquarters, Qwest Communications and, dirctly across the Street, surface parking. These are all active 24 hour operations and contribute to the neighborhood\'s high ambient light level. Considering these factors we have selected lighting for the building which maintains safety for pedestrians while being uniform and understated. along the alley deep shielded Ruud E8-F fixtures are installed at 8\' above the pavement at egress and service doors. On the two street facades at sidewalks, we have utilized Bega 7475MH surface washers mounted at 10\' - 12\' above the walking surface and aimed at the underside of the translucent overhead protection canopies. This provides an even wash of indirect light to the pedestrian walking surface while eliminating the escape of direct light. The fourth side of the building is against the adjacent structure and has no lighting. Three parking levels above street level have cut-off fixtures installed 20\' or more from the exterior walls, further shielded by aluminum screening at the exterior openings to the garage. Lobby lighting is limited to recessed cans, recessesed track and diffuse light from an internally lit large glass sculpture.Our project replaces a surface parking lot that included two unshielded pole area-lights and two 2-sided illuminated billboards. Light level measurements were not taken when these elements were operational so comparative data is not available.I feel that we have responded to both the neighborhood and the credit although the light trespass onto the alley and sidewalks ranges from 2 to 10 footcandles. However, the light trespass onto "adjacent properties" is less than 0.6 footcandles (or 6 lux).I would appreciate your view on this particular situation.

Ruling:

There are multiple components of this CIR that are addressed in the five points below.1. Pedestrian Indirect Lighting: Pages 71 & 72 of the LEED-NC v2.1 Reference Guide discusses design approach strategies to comply with the intent of Sustainable Sites Credit 8. The Guide states "In areas of high ambient brightness, some low level (subtle) lighting of features, facades or landscape areas may be appropriate in pedestrian environments or for identification and way finding" Uplighting a translucent canopy that is continuous around two facades of the building is not consistent with the intent of this credit.To be more consistent with the credit intent, the following steps may help achieve SSc8: (a) Limit uplighting the translucent canopy to key focal points such as main entrances or use opaque material for the continuous canopies. Also, for uplighted areas, provide information about the translucent canopy, showing that the transmittance of the canopy has been minimized. (b) Show that the light distribution is limited to the canopy and does not spill beyond. To help clarify the design, provide a section showing the relationship of the luminaire to the canopy, showing that the photometric distribution from the luminaire is entirely captured by the canopy. (c) Specify a lamp package that has 3500 initial lumens or less. The standard lamp for the Bega 7475MH is a 70 watt metal halide with 6400 initial lumens, which will not meet the credit requirement. (d) Specify a luminaire that has a fixed, non-adjustable mounting. The Bega 7475MH is an adjustable luminaire that would allow changing of the intended aiming after the installation is complete, and refer to item (b).2. Alley Lighting: It is not clear that the Ruud E8-F luminaire meets IESNA Full Cut-off classification, therefore the lamp package must be 3500 initial lumens or less to comply with this credit, or supply documentation showing that the luminaire meets the full cutoff requirements.3. Light Trespass to Alley and Sidewalk: 2 - 10 footcandles far exceeds the limitation of 0.6 as stated in Table 1 on page 70 of the LEED-NC v2.1 Reference Guide. Refer to SSc8 LEED Interpretation Inquiry #5409 (request date 8/16/2003, ruling date 9/2/2003). Include detailed calculations and drawings similar to those on page 75 of the Reference Guide, showing (a) that the light trespass limitation of 0.6 is met at the curb line of the sidewalk of the 2 street sides and (b) 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 in the alley.4. Parking Garage Lighting: For all levels of the parking garage, show that the peak candela of the luminaires falls within the parking garage. If the top level of the parking garage is open to the sky, provide luminaire cutsheets showing that they meet IESNA full cut-off classification, and meet all other exterior requirements.5. Lobby Lighting: From the description provided, the lighting in the lobby satisfies the requirements of SSc8. Provide a diagram and photometric distributions of luminaires showing that the peak candela falls within the building. Note: all other interior lighting must also meet the requirement that the peak candela falls within the building.

Campus Applicable
No
Internationally Applicable:
No
1/1/2014
LEED Interpretation
Inquiry:

After performing illumination measurement readings, some measurements exceeded the threshold dictated by Option 3, Approach 1: Difference in Illumination levels is 20 percent or less. The uncertainty of the light meter used is over six times the captured light level, which could be a result of the inability of a calibrated meter to obtain accurate readings due to low light levels on the project. Even though some measurements exceed the Option 3 threshold, we feel that the project's low light levels meet the intent of the credit. Can readings that are exceeded by the uncertainty of a calibrated light meter be excluded from Option 3?

Ruling:

The proposed strategy of excluding readings that are exceeded by the light meter uncertainty is not acceptable for SSc8 Light Pollution Reduction. Due to the calculation method of the uncertainty of the light meter, in low light situations where the difference in readings with the exterior lights on and off is less than the uncertainty of the meter this would apply to a far greater number of data points than those with minimal differences in lighting.

As an alternative, projects may demonstrate that measurement points meet the values listed in New Construction SSc8 Light Pollution Reduction for the project’s lighting zone. A combination of strategies is allowed, however each measurement point must comply with one of the strategies, with no exceptions or averaging across data points.

Campus Applicable
Yes
Internationally Applicable:
Yes
5/9/2011
LEED Interpretation
Inquiry:

Can projects uplight a single flagpole, as previously allowed under NC 2.1?

Ruling:

While it is correctly pointed out that previous CIRs have addressed this issue for LEED-NC v2.1, it should be noted that due to the changes to how sky glow concerns are now addressed by this credit, the old CIR is not applicable to LEED 2009 projects. Therefore, uplighting a flag is permissible provided that the credit requirements (including that the total percentage of light emitted above 90 degrees from nadir is within the allowable threshold relative to the declared environmental zone) are met.It should further be noted that there are many manufacturers of flagpole downlighting. It is recommended that the project team work with an exterior lighting designer to identify additional options.Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:

Can multifamily projects be exempt from the interior lighting requirements?

Ruling:

Yes, multifamily LEED projects are exempt from the Interior Lighting requirements of this credit. Residential spaces (dwelling units only) within the scope of other LEED projects are also exempt from the Interior Lighting requirements. Item #3 in LEED Interpretation #5149 ("[3] Residential spaces may not be exempted from the interior lighting requirements.") is now void.

Campus Applicable
No
Internationally Applicable:
No
6/1/2009
LEED Interpretation
Inquiry:

We currently have accent lightings that are not fully shielded accenting statues on the crown of our building. These lights are turned on for an average of six hours per night, fluctuating depending on the time of year. The current lights are 120W halogen bulbs. Per the reference guide, these would have to be fully shielded if we were to qualify for SS 8. We are proposing a project to remove these lights and replace them with dramatically more efficient LED lights that will be well under 50W, reducing the energy usage by an estimated 500%. We want to confirm the exclusion in Option B relating to fully shielded fixtures listed for 50W and under exterior lights on page 108 in the reference guide to make sure we are eligible for SS 8 on this project. By doing this, all exterior lights above 50W will be shielded and we will have a marquee project utilizing a new technology that will be presented to the building tenants as part of a tenant education program highlighting our sustainable technology.

Ruling:

Fixtures less than 50 watts are excluded from the shielding requirements for EB O&M SSc8 Exterior and Site Lighting Option B. Buildings with no exterior or site lighting fixtures at 50 watts or more would also meet the requirements for SSc8 Option B. This project would be eligible for EB SSc8 Option B only if the unshielded accent lights were completely replaced by LED fixtures that are less than 50 watts before the start of the performance period and SSc8 interior lighting criteria were met as well. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
3/14/2003
LEED Interpretation
Inquiry:

Our project is located in the heart of downtown Allentown PA and falls under the lighting category "High Ambient Brightness." The site comprises an eight storey building, approximately 140 in height above grade, and a plaza in front of that building. The plaza is bordered by city streets and sidewalks (not part of our project site), with city standard historic pole mounted fixtures. These fixtures are not cutoff fixtures and distribute light in a radial pattern towards the street, the sidewalk below, and towards the plaza. Our project\'s landscape lighting scheme is designed to balance the perceived brightness from these city street lighting fixtures by utilizing up-lit trees within the plaza as glowing objects that replace the need for additional pole mounted fixtures. Additionally, the plaza incorporates a fountain with up-lit water jets to enliven the plaza at night and add to the perception of the plaza as an occupied public space. Aside from the trees and fountain, all other plaza lighting, and the light levels eminating from the adjacent internally lit 140\' high building, are clearly within proscribed low-level light standards proscribed by the LEED 2.0 Rating System and its associated credit inquiries. We would like the USGBC to confirm that the up-lighting scheme for these plaza trees and fountain conforms to the revised lighting requirements specified in the LEED 2.1 Rating System and thus the general intent of this credit to eliminate light trespass, improve night sky access, and maintain a safe and appropriately lit urban public space.Beginning with the trees, which are the primary lighting component of the plaza, they are nominally 16\' to the top of the canopy. The illuminated undersides of the canopy at this pedestrian scale would significantly contribute to the public perception of a safe environment. Based on detailed computer modeling of the proposed tree lighting scheme, we find an average light level of 2.0 fc directly above the tree canopy when lit from below by the specified recessed up-lighting fixtures. As an additional note, the source is regressed within the fixture suspended from a cast iron tree grate cross louver providing superior cut off shielding of the source. Based on the foot candle levels above the tree canopy, and especially when put in the context of the adjacent street lights and the neighboring tall building, the lighting of these trees meets IESNA standards for low level exterior lighting and we believe that there is effectively no stray light adversely affecting this urban setting.The second area of up lighting in the plaza is the fountain, which comprises water jets that are lit from below by parabolic luminaries. The light fixtures are provided power only when the fountain pumps are active, so there would be no circumstance in which the lights would operate without a water column above the lamp to shield the light source. The effectiveness of the water as a light shield was determined in a measured study of the fountain light levels, which recorded an average light level of 9.06 fc three feet above the water feature when utilizing a 50W MR16 source. The design calls for a 35W lamp instead, which should reduce the measured average light level above the fountain to approximately 6fc. As a note, the luminaires are less than 3500 lumens and do not require full cutoff shielding; because each fixture is recessed well below the level of the paving, the full intensity of a lamp would never be visible since there will always be a column of water atop it. Accordingly, we believe the fountain lighting levels are well within the IESNA standards, especially as the fountain is located between the unshielded city street lights and the 140\' high illuminated building.Please confirm that these two plaza elements with their carefully shielded up-lit elements meet both the specific requirements of LEED 2.1 SS credit 8, and the larger intent "to provide enough illumination for safety, accessibility and public perception while at the same time avoiding unnecessary light pollution."

Ruling:

Under LEED v2.0, uplights are precluded in achieving this credit, as they represent direct beam illumination to the night sky. Under LEED v2.1, clarifications have been made that allow some limited uplighting, primarily for the purposes of lighting the American flag at night.In areas of high ambient brightness only, limited uplighting will be allowed if the following conditions are met: (1) All credit requirements are met, including full cut off luminaires for lamps over 3500 initial lumens and shielding for those over 1000 initial lumens. (2) Lighting controls are used to turn off lighting after hours and/or during post curfew periods. A plan should be developed to insure the use of the controls (automated controls, etc.). Note that some landscape features such as trees and plants (depending somewhat on the type of planting) require a rest from light. (3) Lighting controls are commissioned.In addition to the above conditions (and associated documentation), certain additional information must be provided to demonstrate compliance with the credit intent: (1) The results of a light study that verifies the illumination intensity emitted directly above the feature being lit (in this case, the fountains and the trees). (1a) If trees are being uplit, this study must verify the maximum light levels that will be produced when the trees have dropped all of their leaves. (2) A narrative describing how light levels and glare will be controlled around the trees in each of the seasons and listing the hours of intended uplighting operation for both the water feature and the plaza tree lighting. (3) A statement from your landscape architect indicating that the planned tree lighting will not have adverse effects on the trees\' dormancy cycles. (4) Confirmation that the fixtures and lamps installed are the same as those modeled.Note: the v2.1 Reference Guide language will provide further clarifications; please refer to that document before finalizing your design.

Campus Applicable
No
Internationally Applicable:
No
1/1/2015
LEED Interpretation
Inquiry:

Is there another way for Existing Building projects to meet the interior lighting requirements?

Ruling:

**Updated 7/1/2015 to clarify compliance paths.
Existing Building projects, including spaces that operate 24/7, can demonstrate compliance by following Option 2 in New Construction:

Option 2
All openings in the envelope (translucent or transparent) with a direct line of sight to any non-emergency luminaires must have shielding (controlled/closed by automatic device for a resultant transmittance of less than 10% between 11 p.m. and 5 a.m.).

This interpretation is not applicable to v4 projects because there are no interior lighting requirements in v4.

Campus Applicable
Yes
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

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?

Ruling:

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.

Campus Applicable
No
Internationally Applicable:
Yes

LEEDuser expert

Bill Swanson

PE, LEED AP BD+C

Feyen Zylstra
Sr. Electrical Engineer

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