Equivalent Melanopic Lux (EML): The photopic lux multiplied by a melanopic ratio, EML = LxR. This is essentially a measurement of light’s effect on human circadian rhythm. In general, higher EML light sources (125-250) are specified for daytime activities, while sources with lower EML (>50) are better suited for nocturnal activities. For more information see “Measuring and Using Light in the Melanopsin Age” by Lucas, RJ et al.
Requirements: Electric lighting is used to achieve light levels shown in the table below as measured on the vertical plane facing forward, 1.2 m [4 ft] above the finished floor (to simulate the view of the occupant). Light level may incorporate daylight, and is present for at least the hours between 9:00 AM and 1:00 PM for every day of the year.
Resources: EML Calculator Spreadsheet (provided by the IWBI)