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Guideline I.5: Lighting and Daylighting
Intent
To promote occupant comfort by providing adequate levels of natural and artificial light to maintain sufficient light levels for tasks being performed. Quality lighting can also support cognitive function, mental health, and social interaction while being aesthetically pleasing and complementing the design of the space.
Required Performance Criteria
Guidelines apply to all New Construction projects and for Major Renovations which include replacement or construction of relevant systems and assemblies.
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- Light levels:[1]
- Provide adequate light levels according to Illuminating Engineering Society (IES) guidelines not including daylighting contributions for regularly occupied spaces. These light levels shall be:
- Measured at task plane.
- Maintain contrast levels by demonstrating one of the following:
- Average wall surface to average work surface illuminance level not to exceed a ratio of 1:3.
- Average ceiling surface to average work surface illuminance level not to exceed a ratio of 1:10.
- Provide adequate light levels according to Illuminating Engineering Society (IES) guidelines not including daylighting contributions for regularly occupied spaces. These light levels shall be:
- Lamp specifications:[2]
- Use light sources with a color rendering index (CRI) of at least 80, unless necessary for special use.
- All light sources should be Restriction of Hazardous Substances (RoHS) compliant following the most current European RoHS requirements
- Daylighting:
- On facades facing within 45 degrees of east, south or west: provide glare control devices with manual operation (or automatic with manual override) for 90% of all regularly occupied spaces.
- Demonstrate daylight utilization with one of the following:
- Demonstrate achievement of spatial daylight autonomy (sDA) for at least 50% of regularly occupied space.
- Demonstrate that daylight alone provides illuminance levels within 20% of IES recommendations for 75% of regularly occupied space at 9 a.m. and 3 p.m. on a clear-sky day at the equinox.
- Demonstrate achievement of a daylight factor of at least 2% in 80% of regularly occupied space.[3]
- Light levels:[1]
Recommended Performance Criteria
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- Use light sources with a CRI of at least 90.
- Light direction and glare: Use direct-only overhead lighting for 25% or less of total connected lighting load in all regularly occupied spaces.[1]
- Interior surface reflectance: Specify interior surfaces (walls, floors, ceilings, permanently installed furniture) for all regularly occupied spaces that meet or exceed the following area-weighted average reflectance values to maximize lighting efficiency and to increase the perceived brightness of spaces:
- Ceilings: at least 85% average surface reflectance.
- Walls: at least 60% average surface reflectance.
- Floors: at least 25% average surface reflectance.
- Furniture:
- At least 45% average surface reflectance for work surfaces.
- At least 50% average surface reflectance for movable partitions.
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