Light
Core concepts
WELL v2 Light supports visual performance, circadian health, and comfort. Preconditions address light exposure, visual lighting design, circadian lighting design, and electric-light glare control. Optimizations include daylight modeling, daylighting, electric light quality, occupant control, solar glare control, light at night, and lighting education.
Visual lighting design is about task illuminance, uniformity, and color quality. Circadian lighting design considers the timing, spectrum, and intensity of light that influences melatonin and alertness-not just whether a room is “bright enough.” Glare control is separate: a space can be well lit and still fail because of disability glare or discomfort glare. Daylight modeling predicts performance; daylighting implements design. Occupant control lets people adjust blinds or electric light.
Traps
Do not equate high illuminance with good circadian design; timing and spectrum matter. Do not treat daylight modeling as a substitute for actual daylighting features. Solar glare control and electric-light glare control are distinct. “Light at night” is about reducing disruptive light exposure after hours and outdoors, including shielding and blue-rich light limits.
Rule of thumb
If the problem is too much sun on a screen, think solar glare control; if the problem is a harsh fixture, think electric-light glare control; if the problem is poor sleep, think circadian design and light at night.
Worked example
A west-facing office has abundant daylight but occupants use cardboard to block afternoon sun. The project may satisfy daylight quantity but fail glare control. The fix is exterior shading, blinds, or automated glare control, plus occupant access.