lightoften

Lightoften is a proposed metric used in lighting design and chronobiology to describe how frequently a space receives light over a given period. The term combines light and often, signaling a focus on temporal prevalence rather than intensity.

Definition and scope: lightoften denotes the fraction of time within a defined interval during which lighting exceeds a defined threshold. It is distinct from illuminance (lux), which measures instantaneous light level, and from photoperiod, which records day length.

Measurement and calculation: sensors record light presence or above-threshold status at regular intervals. Lightoften = number of intervals with light > threshold divided by total intervals in the period. Thresholds may vary by context (for example, indoor spaces might use 50 lux, outdoor daylight uses higher thresholds).

Applications: used to assess lighting design, energy efficiency, and potential circadian impact. Helps compare spaces with different lighting schedules, and to study ecological impacts of artificial lighting on wildlife and urban fauna.

Limitations and status: standardization lacking; threshold choice and sensor placement affect results; not widely adopted; more research needed to validate its uses and establish guidelines.

See also: photoperiod, illuminance, circadian lighting, daylight autonomy.