2023 Quantification of Perceived Spatial Brightness: Feu and MRSE

Craig Bernecker, The Lighting Education Institute/Parsons School of Design and An Hsu, One Lux Studio

March 8, 2023

2:00pm – 3:00pm EST

Room Location: Nassau

Credit: 1 LU / Elective

Several attempts have been made to define metrics other than illuminance to establish recommended light levels for spaces. Two of these, Feu and Mean Room surface Exitance (MRSE) are explored and compared relative to their prediction of the perceived level of light in spaces. Based on the initial work of a student thesis using computer analyses to evaluate how interior reflectance and light distribution influence perceived spatial brightness, the work is extended to conduct the same analyses with MRSE. Using this comparison, recommendations are made for Feu and MRSE for different applications in lieu of illuminance recommendations.

Familiarity with illuminance is recommended for this session

Learning Objectives

  1. Participants will recognize that illuminance recommendations do not always correlate with the perceived adequacy of light in a space.
  2. Participants will be able to identify the parameters that determine the FEU for a given space.
  3. Participants will be able to determine the mean room surface exitance (MRSE) for a space.
  4. Participants will be able to compare the FEU value and MRSE for a space and evaluate which metric better correlates with the perceived adequacy of light of light.


Craig Bernecker

Craig Bernecker
Professor of Lighting Design, The Lighting Education Institute/Parsons School of Design

Dr. Bernecker has been a lighting educator for over 40 years. He is founder of The Lighting Education Institute and Professor of Lighting Design and Director of the Masters of Fine Arts in Lighting Design program at Parsons School of Design, The New School. Prior to founding The Lighting Education Institute, he directed the lighting education program within the Department of Architectural Engineering at Penn State University. He has published more than fifty articles on research and education in lighting design and illumination engineering and is known for his work on the psychological aspects of lighting. He also maintains an active consulting practice, providing lighting design services and serving as an expert consultant on many projects and as an expert witness on many legal cases. He regularly serves as a peer reviewer for lighting research proposals and projects sponsored by the U.S. Department of Energy.

He further has served for 15 years as Educational Facilitator for LIGHTFAIR International, coordinating the development of the annual conference program, and annually teaches the IES online lighting certification review course in preparation for the NCQLP LC exam.

Dr. Bernecker has served the Illuminating Engineering Society of North America (IESNA) as Vice-President for Technical and Research Activities (1991-1993) and Vice-President for Educational Activities (1993-1995). More recently, he served the Society in its highest office, as Senior Vice-President for 2003-2004, President for 2004-2005, and Immediate Past President for 2005-2006. As a result of his contributions to lighting education, the Society named him a Fellow in 1991, and for his service to the IES, the Distinguished Service Award in 2017. He also recently received the 2021 LIT Lighting Design Awards Lifetime Achievement Award.

An Hsu

An Hsu
Lighting Designer, One Lux Studio

An Hsu is a designer and thinker with a passion for architecture and lighting design.
She graduated from Parsons MFA in Lighting Design in May 2022 and now working as a lighting designer at One Lux Studio. Before studying at Parsons, she worked as an architectural designer for two years in Taipei. Acquiring knowledge of different majors has enriched her discussions of lighting design and architecture, and new ways of thinking have been a huge source of inspiration. She believes that light embodies the qualities of place as it interacts with the building form, materials, surface textures, hues, and reflectance. She aims to redefine the relationship between space and light, and looks forward to using light to tell the story of spaces.


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