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Light & Engineering 26 (2)

Light & Engineering 26 (2)

Volume 26
Date of publication 07/01/2018
Pages 68-74

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Effective Radiant Flux for Non-image Forming Effects – is the Illuminance and the Melanopic Irradiance at the Eye Really the Right Measure . L&E 26 (2) 2018
Articles authors:
Kai Broszio, Martine Knoop, Mathias Niedling, Stephan Völker

Is a Ph.D. student in the field of non-image forming effects on humans at the Chair of Lighting Technology, TU Berlin. He studied Electrical Engineering with a specialization on lighting technology and photovoltaic and worked on the European project Energy Saving Outdoor Lighting (ESOLi). He is currently working as teaching and research assistant at the Chair of Lighting Technology. His doctoral thesis deals with the impact of directionality of light on non-image forming effects. He is a guest member of the indoor lighting expert group of the German Society of Lighting Technology (LiTG)

Is a lecturer at the Chair of Lighting Technology, Technische Universitöt Berlin (TUB), Germany. She is responsible for research and education on indoor lighting, daylighting and colorimetry. Before taking up her assignment at the TU Berlin, she was a senior application specialist of Philips Lighting, the Netherlands and part-time visiting professor at Eindhoven University of Technology. Her current research focuses on the unique characteristics of daylight. It aims to promote and improve daylight design, as well as to develop new adaptive electric lighting solutions, to enhance user well-being and performance in interiors

Is a Ph.D. student and former technical project manager, and teaching assistant at the Chair of Lighting Technology, TU Berlin. He studied Media Technology at Ilmenau University of Technology. From 2008 to 2010, he worked as a development engineer at OLIGO surface controls. His current work focuses on non-image forming effects, glare, and outdoor lighting. His doctoral research examines the influence of glare sources spectra on discomfort and disability glare. Mathias is member of the German Institute for Standardization (DIN) and the outdoor lighting expert group of the German Society of Lighting Technology (LiTG)

Prof., studied Electrical Engineering at the Technical University Ilmenau, Germany. Afterwards, he worked there as a researcher for new high temperature plasma applications. Prof. Voelker accomplished his graduation at the Department of Lighting Technology in Ilmenau in 1999. Thereafter, he was senior engineer and senior researcher at the Hella KG. In 2002, he started working as a junior research professor for Lighting Technology in Paderborn, Germany, where he led an own research group. Additionally, he worked as a guest lecturer at the University College of London. Since 2008, Prof. Völker is full Professor and Head of the Department of Lighting Technology at the Technische Universitöt Berlin, Germany. His main research interests are: adaptive road lighting based on visibility, adaptive indoor lighting for design, glare evaluation of LED-luminaires and day lighting. He is the chair of CIE TC4Р33 and member of CIE TC4Р54 & 4Р52, board member of the LiTG, member of the advisory board of FNL & DIN and member of the TWA

Research indicates that intrinsically photosensitive Retinal Ganglion Cells are not evenly distributed or evenly sensitive throughout the retina. Still, most research looking into non-image forming (NIF) effects uses an integral measured quantity, illuminance or melanopic weighted irradiance, to represent the amount of light at the participantsХ eye level. This paper describes a theoretical approach to define the effective radiant flux for stimulating the ipRGCs, taking into account a spatially resolved sensitivity. Research on retinal sensitivity is scares and not yet substantial, but the methodology can easily be adopted when areas of specific sensitivity are set. Preliminary results indicate that, with similar vertical illuminances and spectral power distribution, typical office lighting solutions might have a lower NIF effectiveness than settings with higher luminances in the central part of the field of view. This could explain why research on NIF effects is inconclusive, even though reported lighting conditions are similar.
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