UL has created a Recommended Practice and Design Guideline for those wanting to support circadian entrainment in buildings. The design guide went out for public comment last week. The Task Group was chaired by Dr. Mark Rea, of the Lighting Research Center.
The document is intended for use by those who design and specify lighting in buildings and wish to provide light for vision and for circadian entrainment for typical day-active people and night-inactive people. The document provides a simple way of implementing circadian-effective light and a method for verification of effect on building occupants.
The Recommended Practice states, “The amount of light equivalent to that , after one hour of exposure, capable of suppressing the production of melatonin at night by 30% (CS=0.30) should be continuously available at the occupant’s eyes for a minimum of two hours during the daytime. In very simple terms, this translates into a vertical illuminance at the eye (EV) of about 350 lx for warm sources and about 200 lx for cool sources, but the exact amount depends upon the spectral power distribution of the light source.