Human-Centric and Circadian Lighting

The emerging human-centric lighting (HCL) technologies that focus on the impact of light on circadian rhythm, health and well-being are growing rapidly, with solutions designed for homes, offices and commercial spaces.

In recent years, acceptance of the link between the lighting we are exposed to each day and its effect on our circadian rhythm has increased interest in measuring circadian effectiveness. Based on industry feedback and the needs of building owners, lighting designers and consumers, UL Solutions has developed field measurement and performance services for consistent testing and reporting of measurable data.

Our performance measurement service and UL Marketing Claim Verification program measure photometric characteristics for luminaire categories, such as recessed troffers, pendants, wall washers, wall sconces, downlights and desk lamps. Spectral power distribution (SPD) is measured at the vertical plane of the observer’s retina, and we then use three algorithms to report the circadian score of the luminaire:

• Equivalent melanopic lux (EML): Based on the International WELL Building Standard
• Circadian stimulus (CS) method: Based on UL Design Guideline 24480 for Promoting Circadian Entrainment With Light for Day-Active People
• Melanopic equivalent daylight illuminance (M-EDI): Based on DIN Technical SPEC 67600

With our Circadian Product iQ® tool, lighting designers can explore the non-visual aspects of luminaires, search circadian luminaire scores and luminaire reports, and compare circadian test results of tested products.

This service can help building owners, designers and specifiers via thorough analysis of existing lighting conditions or by acting as a planning tool for lighting with circadian effectiveness. Lighting measurements in an indoor space are gathered based on the actual light that hits the eyes of building occupants, including reflectance. This data is captured using robotic automation and run through an algorithm to produce a circadian heat map.