PNNL-14506 Lighting Quality and Office Work: A Field Simulation Study Peter R. Boyce1 Jennifer A. Veitch2 Guy R. Newsham2 Michael Myer1 Claudia Hunter1 Judith H Heerwagen, Research Manager Carol C. Jones, Project Manager December 2003 Prepared for the U.S. Department of Energy under Contract DE-AC06-76RL01830 1 Lighting Research Center, Rensselaer Polytechnic Institute RPI # A11106 2 National Research Council of Canada, Institute for Research in Construction NRC # B3214.1 PNNL-14506 Lighting Quality and Office Work: A Field Simulation Study Peter R. Boyce1 Jennifer A. Veitch2 Guy R. Newsham2 Michael Myer1 Claudia Hunter1 Judith H Heerwagen, Research Manager Carol C. Jones, Project Manager December 2003 Prepared for the U.S. Department of Energy under Contract DE-AC06-76RL01830 Pacific Northwest National Laboratory Richland, Washington 99352 1 Lighting Research Center, Rensselaer Polytechnic Institute RPI # A11106 2 National Research Council of Canada, Institute for Research in Construction NRC # B3214.1 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. PACIFIC NORTHWEST NATIONAL LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC06-76RL01830 Printed in the United States of America Available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm This document was printed on recycled paper. Lighting Quality and Office Work: A Field Simulation Study Peter R. Boyce1, Jennifer A. Veitch2, Guy R. Newsham2, Michael Myer1, and Claudia Hunter1 1. Lighting Research Center, Rensselaer Polytechnic Institute, 21, Union Street, Troy, New York, 12180-3352 Tel: 518-687-7130; Fax: 518-687-7120 [email protected] 2. National Research Council of Canada, Institute for Research in Construction, Bldg M-24 1200 Montreal Road, Ottawa, Ontario KIA OR6, Canada Tel: 613-993-9671 / 993-9607; Fax: 613-954-3733 [email protected] / [email protected] A Report for the Light Right Consortium 167 pages September 26, 2003 PNNL RFP # 404141 / RPI # A11106 / NRC # B3214.1 Lighting Quality and Office Work Executive Summary The question this study addressed was, "Can different forms of realistic office lighting affect the performance of office work or the health and well-being of employees?" An office was furnished as a typical open plan workplace for nine workers, with perimeter windows allowing access to a view but limited daylight penetration. Two experiments were conducted. In Experiment 1, there were provisions for changing between four lighting installations: • Base Case: A regular array of parabolic-louvered luminaires • Best Practice: A linear system of direct / indirect luminaires, together with some wall-washing to brighten the walls, with the same average illuminance as the Base Case • Switching Control: The same as the Best Practice but with a moveable desk lamp having three manually switched light outputs, allowing the individual to increase the illuminance in the work area. • Dimming Control: Direct / indirect luminaires suspended over the center of each cubicle, together with the wall-washing system. The direct component of each suspended luminaire could be dimmed using an interface on the occupant's computer, allowing the individual to adjust the illuminance in the work area over a wide range. Experiment 2 contrasted two lighting installations: • Base Case 2: A regular array of recessed prismatic luminaires • Best Practice 2: A linear system of direct / indirect luminaires, together with some wall-washing to brighten the walls, at an illuminance level approximately 27% lower than the Best Practice in Experiment 1. We hypothesized that occupants would prefer, and would perform better in, the Best Practice condition compared to the Base Case, and that having control would result in a further improvement in outcomes. In addition, workstations were decorated using one of two surface reflectances, a light gray and a dark blue. This provided greater variation in vertical surface luminance, which previous research has suggested might influence responses to the luminous environment in concert with lighting system effects. The experiments were designed to test the effects of lighting systems on performance and well-being, as well as indications of the processes that might mediate these effects. What these processes might be is indicated in the Linked Mechanisms Map (Figure ES1), which evolved from the original RFP issued by the Light Right Consortium. Final Report PNNL RFP # 404141 / RPI # A11106 / NRC # B3214.1 Page 2 Lighting Quality and Office Work Figure ES1. Linked Mechanisms Map hypothesized to link luminous conditions with health, well-being, and performance. Personal Luminous Non-task Surface Control Conditions Brightness Appraisal Visual Comfort Visual Capabilities Preference Competence Mood (Affect) Motivation Health and Task Performance Well-Being Both experiments collected data from temporary office workers, who were hired to work under one of the lighting installations for a complete day. During that day the participants carried out tasks involving many forms of clerical and cognitive office work, evaluations of the physical environment, and assessments of their mood. In Experiment 1, we also collected data on switching/dimming choices in the designs in which control was offered. Experiment 1 had two parallel experimental designs: 1. A between-groups design, in which each person was randomly assigned to one of the four lighting conditions, none of which they had previously seen. A total of 181 individuals contributed data to this portion of the experiment. 2. A repeated-measures design, in which 45 individuals returned for a second day of testing under a different lighting condition. This portion of the experiment involved the Base Case and Dimming Control conditions only. Experiment 2 had a between-groups experimental design, in which each person was randomly assigned to one of the two lighting conditions, neither of which they had previously seen. A total of 107 people participated in this experiment. Experiment 2 was an extension and partial replication of Experiment 1. The data from the two experiments were analyzed and interpreted separately. Within each experiment, comparisons between different lighting and partition reflectance conditions were analyzed using orthogonal planned comparisons, which provide for independent tests of specific effects chosen based on the underlying theory. Multivariate analysis of variance was used for sets of measurements relating to concepts for which there were multiple dependent measures, or univariate analysis of variance when there was only one measurement relating to a concept. To examine the validity of the Linked Mechanisms Map, each link in Figure 1 was tested individually, across all lighting conditions. Results • Linked Mechanisms Found. For the lighting installations examined, the Linked Mechanisms Map supports 5 conclusions, two of which involve paths that were not in the original model (see Figure ES2). The first three findings were obtained in both experiments (personal control was not a variable in Experiment 2): Final Report PNNL RFP # 404141 / RPI # A11106 / NRC # B3214.1 Page 3 Lighting Quality and Office Work 1. Vision Path (Luminous Conditions Î Visual Capability Î Task Performance). Lighting and task conditions that improve visibility lead to better task performance. This extends laboratory knowledge to a more realistic setting. 2. Appraisal Path (Luminous Conditions Î Appraisal Î Preference Î Mood Î Health & Well- Being). People who are more satisfied with their lighting rate the space as more attractive, are happier, and are more comfortable and satisfied with their environment and their work. This is the first time that this complete path has been demonstrated. 3. Cross Links. The proposed linkages between the Appraisal Path and the Vision Path were not found. Visual Comfort did not predict Visual Capability; this might be because none of the lighting conditions were very uncomfortable. A similar explanation might hold for the (absent) link between Mood and Motivation. 4. Personal Control Path 1 (Personal Control Î Health & Well-Being). People with dimming control reported higher ratings of lighting quality, overall environmental satisfaction,