Acceptance studies are being carried out in SSL4EU to study user lighting requirements and preferences to be able to suggest preferred spectral distribution for SSL products. These studies are performed in two stages:

            1.    Small-scale lighting booth investigations in laboratories

            2.    Full-scale investigations in office, home and shop lighting environments

Small scale experiments are performed in test booths to restrict the range for optimal solutions for the full scale experiments. Evaluations are based on questionnaires and objective measurements.

Small-scale experiments are carried out at Aalto University Finland, University of Pannonia Hungary and at Osram Germany. In the full-scale experiments Aalto University will concentrate on office lighting, University of Pannonia in home lighting and Osram in shop lighting. A big number of subjects (young and aged) will participate both in the laboratory and full-scale experiments.

The picture shows the triple-booths built at Aalto for the small-scale experiments.

The surface area of each booth is 0.5 m x 0.5 m. Two sections of the booth were installed with variable spectrum LED light source and one section with reference fluorescent luminaire. Various objects representing the objects in office environment were used in the booths. Three different fluorescent lamps at colour temperatures 2700K, 4000K, and 6500K were selected as reference lamps to compare and evaluate the observer’s preference over 21 different LED spectra (7 spectra at each CCT).

The average illuminance on the surface of booth with each lighting setting was maintained between 460 – 470 lx. Altogether 60 observers participated in the test. Observers were selected in two age groups: 20 male and 20 female observers aged 20 to 40 years, and 10 male and 10 female observers aged 50 to 65 years. All the observers were tested for visual acuity and colour vision before accepted for the experiments.

Similar experiments were carried out in Hungary and in Germany. The objects used in Hungary represent those used at homes and in Germany shop related objects were used.