Energy-efficient lighting and visually impaired users in homelike environments

Despite a rapid transition to LED lamps, it is still little knowledge about the effects of these light sources on users with low vision. The study's main objective was to acquire a better understanding about how correlated colour temperatures (CCTs) of non-directional LED affect visual accessibility and perceptions of lighting quality in homelike environments among visually impaired persons. The study took place in a full scale laboratory in which CCTs of 2,700 K and 4,000 K were tested. Participants having normal vision (N=60, 24 males, 36 females, M = 25.50) were divided into three groups of 20 to assess the two lit environments with cataract goggle, severe cataract goggle and normal vision respectively. They were asked to perform everyday activities while the observer recorded the time and conducted observations, and to rate the difficulty of each activity. Thereafter, the participants were asked to rate their perceptions of lighting quality and contrasts in the room. With the same CRI of Ra80, there were no differences in the performance of everyday activities between the two CCTs whereas the differences in the perceived lighting quality and the perceived contrasts were found. The cool white CCT was found to positively affect visual accessibility and perceived contrasts however, its comfort quality remains questionable.