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| v3 - LEED 2009

Light pollution reduction

SSc8 | Possible 2 points

Intent

To minimize light trespass from the building and site, reduce sky-glow to increase night sky access, improve nighttime visibility through glare reduction and reduce development impact from lighting on nocturnal environments.

Requirements

Project teams must comply with one of the two options for interior lighting AND the requirement for exterior lighting.

For interior lighting

OPTION 1

Reduce the input power (by automatic device) of all nonemergency interior luminaires with a direct line of sight to any openings in the envelope (translucent or transparent) by at least 50% between 11 p.m. and 5 a.m. After-hours override may be provided by a manual or occupant-sensing device, provided the override lasts no more than 60 minutes.

OR

Option 2

All openings in the envelope (translucent or transparent) with a direct line of sight to any nonemergency 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.).

For exterior lighting

Light areas only as required for safety and comfort. Exterior lighting power densities shall not exceed those specified in ANSI/ASHRAE/IESNA Standard 90.1-2007 with Addenda i for the documented lighting zone. Justification shall be provided for the selected lighting zone. Lighting controls for all exterior lighting shall comply with section 9.4.1.3 of ANSI/ASHRAE/IESNA Standard 90.1- 2007, without amendments1.

Internally illuminated exterior retail2 signage may be excluded from consideration under this credit.

Classify the project under 1 of the following zones, as defined in IESNA RP-33, and follow all the requirements for that zone:

LZ1: Dark (developed areas within national parks, state parks, forestland, and rural areas)
Design exterior lighting so that all site and building-mounted luminaires produce a maximum initial illuminance value no greater than 0.01 horizontal and vertical footcandles at the LEED project boundary and beyond. Document that 0% of the total initial designed fixture lumens (sum total of all fixtures on
site) are emitted at an angle of 90 degrees or higher from nadir (straight down).

LZ2: Low (primarily residential zones, neighborhood business districts, light industrial areas with limited nighttime use, and residential mixed-use areas)
Design exterior lighting so that all site and building-mounted luminaires produce a maximum initial illuminance value no greater than 0.10 horizontal and vertical footcandles at the LEED project boundary and no greater than 0.01 horizontal footcandles 10 feet beyond the LEED project boundary. Document
that no more than 2% of the total initial designed fixture lumens (sum total of all fixtures on site) are emitted at an angle of 90 degrees or higher from nadir (straight down).

LZ3: Medium (all other areas not included in LZ1, LZ2, or LZ4, such as commercial/ industrial, and high-density residential)
Design exterior lighting so that all site and building-mounted luminaires produce a maximum initial illuminance value no greater than 0.20 horizontal and vertical footcandles at the LEED project boundary and no greater than 0.01 horizontal footcandles 15 feet beyond the site. Document that no more than 5%
of the total initial designed fixture lumens (sum total of all fixtures on site) are emitted at an angle of 90 degrees or higher from nadir (straight down).

LZ4: High (high-activity commercial districts in major metropolitan areas)
Design exterior lighting so that all site and building-mounted luminaires produce a maximum initial illuminance value no greater than 0.60 horizontal and vertical footcandles at the LEED project boundary and no greater than 0.01 horizontal footcandles 15 feet beyond the site. Document that no more than 10%
of the total initial designed fixture lumens (sum total of all fixtures on site) are emitted at an angle of 90 degrees or higher from nadir (straight down).

For LZ2, LZ3, and LZ4
For LEED project boundaries that abut public rights-of-way, light trespass requirements may be met relative to the curb line instead of the LEED project boundary.

For all zones

Illuminance generated from a single luminaire placed at the intersection of a vehicular driveway and public roadway accessing the site is allowed to use the centerline of the public roadway as the LEED project boundary for a length of 2 times the driveway width (centered at the centerline of the driveway).

For projects that are part of a multitenant complex1

A multitenant complex is a master-planned development of stores, restaurants, and other businesses; retailers may share one or more services and/or common areas. Develop a master lighting plan that includes the project site and the surrounding buildings in a comprehensive manner addressing the safety and security issues of the entire project environment by sharing exterior lighting amenities while minimizing light pollution and energy consumption. The master lighting plan must show that it incorporates the credit requirements for interior and exterior lighting as well as the following:

  • ƒƒ How this plan will reduce light trespass and sky glow and how specific projects fit into the overall design.
  • ƒƒ How safety, security, comfort, and economic activity will be enhanced by the use of a master plan.
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.
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