Illuminance measurements through HDR imaging photometry in scholastic environment

Abstract

In this paper the first step of a wide research program regarding analysis of lighting in working places, in order to inquire about effects on visual comfort, health, wellbeing and energy savings are presented. Today, we can assess that a light environment is proper and effective when: (1) photometric quantities reported on European Code EN 12464-1, such as for instance illuminances on task areas, UGR and Colour Rendering Indexes assume convenient values; (2) energy requirements for lighting do not exceed limit values reported in The European Code EN 15193. However, lit environments are much more complex especially when more than one visual task for the same work position is present and daylighting is available. In order to establish connections between results obtained from photometric measures and visual performance and comfort, statistic experimental surveys based on measures in field and questionnaires are needed. For this aim a school environment has been chosen as a case-study: in fact in school facilities, comfortable and efficient visual conditions for people with different ages and functions as students, teachers and office staff, should be achieved. In particular, it is in the classrooms that teachers and students spend most of their time and in which very different visual tasks are performed, as reading on desks and on blackboard, establishing visual communication between teacher and pupils, watching on maps on walls, etc. Besides in the classrooms there are always several task areas (at least one for each student's position), during the school hours lessons cannot be interrupted for long time and daylight levels can vary during the survey: for these reasons fast and at the same time accurate measures should be carried out. These experimental data are very important in order to design integrated daylighting–artificial lighting systems with good energy performances.In this paper the high dynamic range (HDR) imaging method is applied in order to measure illuminance values on task areas: this technique is promising for wide data collection and processing for energy savings and comfort purposes. From the first results compared with those obtained with a traditional luxmeter, the potentiality of this methodology applied to the luminous environment survey appears evident.