Light at night
- 53 Visual lighting design
- 54 Circadian lighting design
- 55 Electric light glare control
- 56 Solar glare control
- 57 Low-glare workstation design
- 58 Color quality
- 59 Surface design
- 60 Automated shading and dimming controls
- 61 Right to light
- 62 Daylight modeling
- 63 Daylighting fenestration
- P2 Light at night
- P3 Circadian emulation
P2. Light at night
Intent:
To provide sleeping spaces free from light intrusion and provide low-light wayfinding options.
Light is the primary zeitgeber, the signal by which the body aligns its internal clock with the external environment. Therefore light at night is a potential hazard as it can disrupt circadian rhythm. It blurs the distinction between day and night, and affects the timing of the sleep-wake cycle. However, complete darkness increases the sensitivity of the eyes, so any lights encountered during activities at night have an amplified disruptive effect.
Part 1: Window Light Elimination
All bedroom windows employ one of the following:
a. Blackout shades with 0% transmittance and no light gaps on the perimeter.
b. Operable outdoor shutters with 0% transmittance.
Part 2: Electric Light Elimination
In all bedrooms, the following requirement is met:
a. All electronics have an option to produce no light.
Part 3: Safe Nighttime Navigation Lighting
The following conditions are met:
a. Nightlights are installed to provide a safe path from all sleeping areas to the closest bathroom and within the bathroom.
b. Nightlights are located no higher off the ground than 36 cm [14 inches] to the center of the unit.
c. Nightlights are motion-activated with a manual off and manual on option.
d. Nightlights do not emit light at wavelengths below 550 nm.
e. Each nightlight does not produce more than 15 lumens.
Applicability Matrix
| Commercial Kitchen | Education | Multifamily Residential | Restaurant | Retail | |
|---|---|---|---|---|---|
| Part 1: Window Light Elimination | - | - | O | - | - |
| Part 2: Electric Light Elimination | - | - | O | - | - |
| Part 3: Safe Nighttime Navigation Lighting | - | - | O | - | - |
Verification Methods Matrix
| Letters of Assurance | Annotated Documents | On-Site Checks | |
|---|---|---|---|
| Part 1: Window Light Elimination | Visual Inspection | ||
| Part 2: Electric Light Elimination | Visual Inspection | ||
| Part 3: Safe Nighttime Navigation Lighting | Visual Inspection |