Calculations: Light

Feature 53 Visual Lighting Design

  • Maximum Size of Ambient Lighting Zone:  Whichever is larger:
    • 500 sq. ft. (46.5 sq. m.)
    • 20 % of the space

 

Feature 54 Circadian Lighting Design

  • If light models/calcs are used, need to provide:
    • Measured in vertical plane, 4 ft. high (seated gaze height)
    • 250 EML (Equivalent Melanopic Lux) minimum
    • 4 hours / day, minimum, every day
    • At 75% of workstations
  • Feature 54 Circadian Lighting Design, Table L1 Melanopic Ratio
    • Equivalent Melanopic Lux (EML) = Visual Lux (L) x Melanopic Ratio (R)

 

Feature 59 Surface Design

  • Minimum areas of interior surfaces required to have minimum Light Reflectance Values:
    • Ceilings: Min. 80 % area: Min. LRV = 0.8 (80%)
    • Walls: Min. 50% area: Min. LRV = 0.7 (70%)
    • Furnture: Min. 50% area: Min LRV 0.5 (50%)

 

Feature 61 Right to Light

  • Guidelines for regularly occupied spaces and seats:
    • Spaces: 75% (by area) needs to be within 25 ft. (7.5 m) of a view window
    • Seats:
      • 75% need to be within 25 ft. (7.5 m) of a view window or atrium
      • 95% need to be within 41 ft (12.5 m) or a view window or atrium

 

Feature 62 Daylight Modeling

  • Minimums:
    • At least 55% of regularly occupied spaces
    • Receive at least 300 lux (28 fc)
    • For at least 50% of the year (business hours)
  • Maximums:
    • No more than 10% of regularly occupied spaces
    • Receive not more than 1000 lux (93 fc)
    • For more than 250 hours / year

 

Feature 63 Daylighting Fenestration

  • 3 guidelines for window size, shading and placement:
    1. Size:  20% – 60% of exterior wall area should be glazed.
    2. Shading:  If window area is > 40%: prevent glare and heat gain with exterior shading or electrochromic glass.
    3. Daylight effectiveness:  40% to 60% of the window area should be above 7 ft (2.1 m)

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