Light Pollution Reduction - 1 Point

Schools - Sustainable Sites

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 1 of the 2 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 30 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. Lighting power densities must not exceed ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) for the classified zone. Meet exterior lighting control requirements from ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda) Exterior Lighting Section, without amendments.

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, forest land 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 site 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 site boundary and no greater than 0.01 horizontal footcandles 10 feet beyond the site 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 site 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: High2 (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 site 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).

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

For All Zones - Illuminance generated from a single luminaire placed at the intersection of a private vehicular driveway and public roadway accessing the site is allowed to use the centerline of the public roadway as the site boundary for a length of 2 times the driveway width centered at the centerline of the driveway.

Sports Field Lighting (Physical Education Spaces)

Physical education spaces (playing fields) do not need to comply with the lighting power density requirements of this credit, as per ANSI/ASHRAE/IESNA Standard 90.1-2007 section 9.4.5, exception E.

Automatic Shutoff: All sports lighting must be automatically controlled to shut off no later than 11 p.m.. Manual override must be provided to avoid disruption of school sponsored sporting events.

Trespass Calculations

All trespass calculations must be submitted for 2 conditions: (1) with the sports lighting turned off and all other site lighting turned on, the light trespass requirements are as stated above, and (2) with just the sports lighting turned on, the light trespass requirements for horizontal and vertical footcandles (fc) may be increased to the following illuminance levels:

• LZ1 = 0.10 fc at the site boundary, dropping to 0.01 fc within 10 feet of the boundary
• LZ2 = 0.30 fc at the site boundary, dropping to 0.01 fc within 10 feet of the boundary
• LZ3 = 0.80 fc at the site boundary, dropping to 0.01 fc within 15 feet of the boundary
• LZ4 = 1.50 fc at the site boundary, dropping to 0.01 fc within 15 feet of the boundary

Referenced Standards

• ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for Buildings Except Low-Rise Residential - Lighting (Section 9), www.ashrae.org, (800) 527-4723.
• IESNA RP-33-99, Lighting for Exterior Environments, http://www.ies.org/store/product/lighting-for-exterior-environments-1022.cfm .

Design Strategies

• Projects should consider the use of low intensity, shielded luminaires and curfew controllers turning the lights off at 10p or at closing (whichever is later).
• Projects should minimize the lighting of architectural or landscaping features.
• Where lighting is required, utilize down-lighting instead of uplighting.

General Strategy for Designing Exterior Lighting:

1. Employ a lighting professional.
2. Review all applicable lighting ordinances and by-laws.
3. Document which environmental zone the site in in.
4. Use the least amount of lighting equipment while remembering it is sometimes better to use two luminaires with lower light output and good glare control instead of a single high output luminaire.
5. Select all lighting equipment carefully watching for glare, unneeded uplight and light trespass possibilities.
6. Design the exterior lighting so as to minimize reflected light going upward.
7. Light only areas that require lighting, using the least light possible. Design and develop a control scheme to minimize or turn-off lighting after hours.
8. Use a computer modeling tool to provide point-by-point illuminances throughout the space and off-site.
9. Commission and maintain the lighting system.