LRC - Results

Light Right Consortium, Albany Research Study Dimming Control Condition

Download the Summary of Key Findings for the Albany Lab Study.

The first Light Right Consortium research project was conducted in an office building in Albany, NY.

project description

The question this study addressed was, “Can different forms of realistic office lighting affect the performance of office work or the well-being of employees?” An office was furnished as a typical open plan workplace for nine workers, and two experiments were conducted with a total of 6 different lighting conditions. 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. The results showed that occupants appreciated quality lighting and had preferences that were consistent with our predictions.

Satisfaction with the lighting influenced other areas of preference. 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.

Lighting designs that provided direct/indirect lighting and wallwashing were rated as comfortable by 81%–85% of participants. By comparison, designs that provided only downlight (2x4 troffers) were rated as comfortable by 69–71% of participants. The most preferred design provided direct/indirect lighting, wallwashing, and occupant dimming control of the overhead lighting for their workstation. This design was rated as comfortable by 91%, the highest percentage of the six conditions. (See FIG. 1)

In addition to occupant preferences, the study also found that the presence of personal control had a measurable impact on the motivation of office workers to perform on tasks. Normally, the persistence and vigilance of office workers will decline over the course of a workday. However, the presence of personal control of their lighting increased subject motivation allowing workers to sustain their performance — they persisted longer on difficult tasks and were more accurate on a task requiring sustained attention. (See FIG. 2)

When using the dimming control, subjects showed a wide range of illuminance (desktop light level) preferences. On average, people with dimming control chose lower levels than current practice. However, although people on average chose lower illuminances, the diversity of preferences suggest that if a fixed lower ambient room illuminance is chosen it must be supplemented with some means of providing higher local light levels for those who prefer them. (See FIG. 3)

FIG. 1.

Six conditions were provided and rated by comfort level. The addition of room surface brightness and personal control improved occupant comfort.

FIG 2.

Occupants with dimming control had increased motivation and were able to sustain their persistence and vigilance over time, as compared to those without any control of the lighting.

FIG 3.

Mean desktop illuminance chosen by participants with dimming control. Includes data from both between-groups and within-groups designs.