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855773667-LEED-v5-O-M-Reference-Guide-Launch-Edition-1 - Page 093

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Option 1. Limit Uplight

Avoiding uplight is an effective strategy to reduce light pollution. Uplighting occurs from exterior and interior fixtures that direct light upwards. Teams must implement measures for both exterior and interior lighting.

UPLIGHT

All exterior fixtures with a light output greater than 1,000 lumens must meet the full cutoff requirements defined in the IESNA Cutoff Classifications .

The Illuminating Engineering Society of North America (IESNA) defines several cutoff classifications for outdoor luminaires, which help manage light pollution and improve visibility. These include:

  • Full cutoff . No light is emitted at or above a 90° angle from the nadir (directly downward). Additionally, at 80° above the nadir, the luminous intensity does not exceed 10% of the total light output.

  • Cutoff . Light emitted at or above 90° does not exceed 2.5% of the total light output, and at 80° above the nadir, the luminous intensity does not exceed 20%.

  • Semicutoff . Light at or above 90° does not exceed 5% of the total output, while at 80° above the nadir, the luminous intensity does not exceed 20% of the total light output.

  • Noncutoff . There are no restrictions on light emitted above the maximum intensity angle.

INTERIOR LIGHTING

All nonemergency interior lighting fixtures must meet at least one of the following measures to reduce light trespass from the building:

  • Install lighting systems with automatic scheduling that limit the amount of time fixtures which are allowed to be on at night to up to 90 minutes.

  • Lighting fixtures or luminaires that directly emit light to the outdoors through unshielded windows or skylights must be programmed to automatically turn off during nighttime hours.

  • Install shielding or automatic shades on all exterior openings that block at least 90% of the light that can pass through the glazing to the outside.

  • For non-residential spaces, at least 50% of lighting located along the exterior walls of the building must be automatically programmed to turn off during nighttime hours.

Any non-emergency lighting within covered parking areas must also meet the interior lighting requirements of this credit. For the measures using lighting controls, controls may be automatic

U.S. Green Building Council LEED v5 Reference Guide for Operations and Maintenance, April 2025 Launch Edition 83

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