Subjective impressions as quality indicators of ambient lighting

Although ambient lighting can significantly contribute to city beautification, it is often designed similar to street lighting, using high-pressure sodium lamps, inadequate for spaces where colour appearance and colour rendering are important. Judging ambient lighting implies evaluating the feelings of security, enthusiasm and attraction. LEDs can be confirmed as the best solution for ambient lighting only if compared with light sources adequate for the illumination of parks, squares, etc. (for example, metal-halide lamps). In order to compare the subjective impressions created by LED and metal-halide lamps a survey was carried out in a Belgrade park. Both lighting installations had three photometric parameters with approximately equal values: illuminance, colour temperature and colour rendering. The respondents rated their impression of metal-halide lighting as better regarding all aspects. The results confirmed the importance of research based on subjective indicators. An additional analysis was done using a new method which introduced the weighting factors