Site and Water Guidelines

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S.5 Light Pollution Reduction

Intent
Eliminate light trespass from the site, improve night sky access, and reduce development impact on nocturnal environments.

Required and Recommended Performance Criteria apply to all projects in the New Buildings Path and for all new exterior lighting scope within Major Renovations projects.

Required Performance Criteria
All S.5 Required Performance Criteria apply to all projects in the New Buildings Path and for all new exterior lighting scope within Major Renovations projects.

Light Trespass:

  1. A. Do not exceed the following night-time (sunset to sunrise) vertical illuminance values for each of the four exterior lighting zone types defined below. The illuminance measurement shall be at 5ft above ground level, along the site property line and facing into the site, perpendicular to the site property line. Vertical illuminance solely from site lighting fixtures may be used; light reflectance off of site surfaces may be ignored in meeting this criteria.

    Table for S.5A Light Trespass Limitations

    Environmental Lighting Zone Description Maximum Vertical Illuminance Levels [fc] at Property Line
    E1: Intrinsically Dark Parks and residential areas where controlling light pollution is a high priority 0.1
    E2: Low Ambient Brightness Outer urban and rural residential areas 0.1
    E3: Medium Ambient Brightness Urban residential areas 0.2
    E4: High Ambient Brightness Urban areas having both residential and commercial use and experiencing high levels of nighttime activity 0.6

    Note: This Table was adapted from IESNA RP-33-99, using "post curfew" recommendations for all values to ensure that light trespass is minimized for each environmental zone. In situations where the property line is very close to the area of development (commonly referred to as "zero property line"), and where lighting is required for emergency egress purposes, it may not be possible to meet these recommendations and an exception may be made for lighting within 10 feet of these areas. Carefully explain and document these conditions.

Recommended Performance Criteria
All S.5 Recommended Performance Criteria apply to all projects in the New Buildings Path and for all new exterior lighting scope within Major Renovations projects.

Light Pollution or Sky Glow:

  1. Reduce Upward Emissions:

    For Parking Lot and Security Lighting areas:

    For the same environmental lighting zones as defined above for light trespass, achieve the following light distribution characteristics:

    • Zone E1: Use Luminaires with light distribution that meets IESNA's "Full Cutoff Fixtures"
    • Zone E2: Use Luminaires with light distribution that meets IESNA's "Cutoff Fixtures"
    • Zone E3: Use Luminaires with light distribution that meets IESNA's "Semi-Cutoff Fixtures"
    • Zone E4: Use Luminaires with light distribution that meets IESNA's "Cutoff Fixtures

    For facade, display, sculptural and sign lighting:

    • For luminaires of 3500 or more lumens, light objects from above
    • For luminaires of less than 3500 lumens, objects may be lit from below. Make an effort to minimize non-target light (maximize the percentage of uplight that falls on the target)

  2. Create lighting control zones and provide lighting control devices for parking lot, security, and decorative and fa├žade lighting so that each type of lighting can be controlled independently and can be turned off or reduced in response to reduced lighting needs during low use or non-use periods.

    Note: The principles for sky glow criteria S.5 B-C are adapted from principles outlined in IESNA RP33-99, Lighting for Exterior Environments.

Light Quality:

  1. Use lamps with a minimum CRI of 65 in areas of safety/security (i.e. main walking routes through large parking lots, isolated areas), at building entrances, and locations where identification of objects or individuals is essential.

Compliance Tools and Resources

  • Illuminating Engineering Society of North America (IESNA) Recommended Practice (RP-33-99) Lighting for Exterior Environments.

Related B3 Guidelines Documents

Supplemental Resources

  • Illuminating Engineering Society of North America (IESNA) Technical Memorandum TM-10-00, Addressing Obtrusive Light (Urban Sky Glow and Light Trespass) In Conjunction with Roadway Lighting.
  • Illuminating Engineering Society of North America (IESNA) Technical Memorandum TM-11-00, Light Trespass: Research, Results and Recommendations.
  • International Dark-Sky Association, www.darksky.org

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