Lighting for the Classroom of the Future: Acceptability of Glare

This project will investigate glare on display screens, a critical factor for lighting in the classroom of the future. This will be done using subjective ratings of the acceptability of glare on display screens, from which to identify the limiting criteria for lighting design, and thus testing the prediction that the limiting criteria given in current British Standards are no longer valid. The Department for Education and Skills (DfES) has recently launched two initiatives which aim to deliver inspiring and sustainable educational facilities. The Classrooms of the Future programme was initiated in 2003 to experiment with new ideas for designing educational environments for the 21st Century. The Building Schools for the Future programme was launched in 2004 to renew every secondary school in England over a 10-15 year period. The classroom of the future will take advantage of developments in Information and Communication Technology (ICT), an evolution toward learner-centred rather than teacher-centred modes of learning. Increased use of ICT will necessitate expansion in provision of Display Screen Equipment (DSE), the visual interface for ICT, and these self-illuminated objects demand different lighting considerations to traditional paper-based tasks. The visual environment, and hence interior lighting, affects a learner's ability to perceive visual stimuli and affects his/her mental attitude, and thus affects performance. Therefore, a review of strategies for classroom lighting is needed to complement proposals for new approaches to teaching and learning. This need can be identified through the announcement in 2006 from the Society for Light & Lighting of their intention to review design guidance for educational facilities. Preliminary research has included a survey teachers and pupils from ten schools. Their responses reveal problems of veiling reflections on interactive whiteboards and PC screens. Veiling reflection is glare caused by the reflectance of a bright surface, such as a light source or window reflected on the screen of a PC. This can cause a reduction in character-to-background contrast, reducing the legibility of screen characters, which at the extreme can cause the contents of the screen to become unrecognisable. In the UK, Lighting Guide LG5 gives lighting design guidance for classrooms. For the control of glare on DSE, LG5 refers to LG3 which prescribes limits for the luminance of luminaires according to the classification of the DSE screens used in the room. DSE screens are allocated into one of three categories according to tests prescribed in BS 9241-7:1998 and BS 13406-2:2002. For positive polarity screens, the limits of luminaire luminance are up to 1500 cd/m2 for screen categories I and II. However, recent tests have shown that much higher screen luminances are tolerable, due to progressive improvements in screen technology. Furthermore, there are no guidelines for lighting in rooms using interactive whiteboards, the whole-class interface in the classroom of the future. Therefore, there is a need to review and update the thresholds used to define screen categories, and/or to revise the limits of luminaire luminance in these categories. This would allow more flexibility in lighting design, allowing more attention to be paid to the overall visual environment and energy consumption. The Lighting for the Classroom of the Future project at the University of Sheffield is investigating several issues including designing lighting to accommodate a variety of simultaneous tasks, using visual performance and visual acceptability models to predict appropriate design conditions, investigation of screen glare and consideration of energy consumption. This proposal seeks funding to carry out the experimental work needed to investigate one of these issues, that of measuring the acceptability of veiling reflections on DSE. Contact: Dr Fotios, University of Sheffield

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