Table 3.

Guidelines published by the WELL Building Standard v2 and Underwriter's Laboratory 24480.

Standard	Temporal pattern		Lighting quantity (Note: these are a function of light level and spectrum)				Location
	Timing of exposure	Duration of exposure	Circadian stimulus (CS) (Percent)	Equivalent melanopic Lux (EML) (Melanopic Lux)	Melanopic equivalent daylight illuminance (Melanopic EDI) (Lux)	PhotopicIlluminance (Lux)
WELL v2.0Requirements for 1 point	At least between the hours of 9 a.m. and 1 p.m. Light levels may be lowered after 8 p.m.	Minimum of 4 h.	≥0.30 (if electric light only)	≥150 (if electric light only)≥120 from electric lighting (if certain daylighting criteria are met)	≥ 136 (if electric light only)≥109 from electric lighting (if certain daylighting criteria are met)	N/A	Vertical plane at eye level
WELL v2.0Requirements for 3 points	At least between the hours of 9 a.m. and 1 p.m. Light levels may be lowered after 8 p.m.	Minimum of 4 h.	N/A	≥240 (if electric light only)≥180 from electric lighting (if certain daylighting criteria are met)	≥ 218 (if electric light only)≥163 from electric lighting (if certain daylighting criteria are met)	N/A	Vertical plane at eye level
UL 24480	7 a.m.−4 p.m.	Minimum of 2 h, morningIf not full period	≥0.30	Comply with WELL criteria shown above based on desire for 1 point or 3 points	N/A	≥500	Vertical plane at eye level
	5–7 p.m.	During full period	≤ 0.20		N/A	N/A
	After 8 p.m.	During full period	≤ 0.10		N/A	N/A

Note that where alternative compliance paths are offered, either CS, EML, EDI, or Photopic Illuminance can meet the criteria.