Glare rating at different ages: the limits of the UGR method applied to a real case study

The Unified Glare Rating approach (UGR) is widely used in standards to estimate glare caused by lighting. However, its formulation loses reliability when applied to specific LED sources, complex geometries and irregular lighting configurations. Moreover, the standard approach considers a uniform group of people between 20 and 40 years old without accounting for older subjects. The present work enquires a real case study of a conference hall at the Polytechnic School of Genoa, which is attended by both young students (aged between 20 and 25) and the university of the third age (over 60). The results of the UGR approach are compared to the empirical information collected by questionnaires proposed to the subjects of different age: glare perception is more relevant at younger ages, while it fades at older ages. The numerical results estimated a “perceptible” glare, with a slight underestimation for younger groups and overestimation for older subjects. In addition, the results of the questionnaire show that a proper automation control system could overcome or at least reduce the impact of the reported issues. So, the energy saving obtained by an automatic management of the lighting system is proposed to demonstrate its convenience in terms of both comfort and energy saving.