RADIANCE simulations of Caltrans Marysville office before (above) and after retrofit (below). Note the change in lighting of the walls and elimination of glare from protruding ceiling fixtures.

Researchers in the Building Technologies Program are assessing a lighting retrofit project at the Marysville District Headquarters of the California Department of Transportation.

Also known as Caltrans, the agency has recently completed an installation of deep-cell parabolic luminaires in an open office area that houses design and drafting services for road construction and maintenance in its District 3 headquarters in Marysville. The agency plans to develop specifications for upgrading lighting systems in other offices based on results from assessments of this project.

Rudy Verderber, Francis Rubinstein, Robert Clear, Vincent Berrutto, Werner Osterhaus, and Saba Rofchaei are conducting a detailed analysis of potential improvements in the quantity and quality of illumination in the remodeled space as compared to the original lighting system still intact in other parts of the building. Caltrans project managers and the researchers defined a set of fundamental lighting quality parameters for evaluating the retrofit. During several visits to Marysville, the research team measured illuminance and luminance on task surfaces and more than 100 computer screens in pre- and post-retrofit areas of the building. The analysis procedure also included photographic and video documentation and visual assessments of potential problems, such as glare or contrast reduction on the task surface. A luminance mapper developed by the Lighting Research Group made the luminance measurements. Marysville was its first real-world application, capturing images of luminance distributions within the field of view of office personnel. The resulting digitized images are now being analyzed at LBL.

Caltrans plans to develop specifications for upgrading lighting systems in other offices based on results from this study.

To develop design schemes that improve lighting quality, team members selected prominent spaces representing the facility's existing and new lighting installations for modeling with LBL's lighting simulation program, RADIANCE. In addition, Caltrans workers were asked to complete survey questionnaires so that the LBL researchers can correlate their photometric measurements and visual assessments with the subjective responses of the building occupants. Interviews with workers provided further information about typical work tasks and their lighting requirements. Based on the findings of this research, LBL will propose guidelines for specifying lighting installations in other Caltrans offices around the state.

--Werner Osterhaus

Werner Osterhaus
Windows and Daylighting Group
Building Technologies Program
(510) 486-4042; (510) 486-4089 fax