Twenty-Five Years of Daylighting Research at EPFL
The Solar Energy and Building Physics Laboratory (LESO-PB) of EPFL has been at the forefront of daylighting research for more than 25 years. It initiated the creation of a Swiss Daylighting Competence Centre in 1989 by launching several interdisciplinary research programmes involving physicists, ophthalmologists and architects (LUMEN, 1989). Daylighting architectural design was addressed as a first target, leading to the setting-up of computer daylighting design tools combining building architectural typologies with fuzzy logic (Paule, 1999). New generations of sun and sky simulators (automated heliodon, scanning artificial sky) were also set up, improving the reliability and accuracy of daylighting performance assessment of buildings using physical models (Michel, 1995) (Thanachareonkit et al., 2005). Other European and US research institutions such as University of Urbana-Champaign/USA, Politecnico di Torino/Italy and the Belgium Building Research Institute replicated these technologies. Advanced computer software (Radiance programme), based on ray-tracing techniques (Scartezzini et al, 1994), were developed in collaboration with Lawrence National Berkeley Laboratory (LBNL) and Fraunhofer Gesellschaft (FhG) to address the complexity of light propagation in buildings and daylighting systems (Erhorn et al., 2000) (Kaempf and Scartezzini, 2004).
Future Outlook and Perspective in Daylighting Research at EPFL
Non-imaging optics, well known for its application to solar concentrators (Welford and Winston, 1989), was also used to set up a novel design approach for advanced daylighting systems, the so-called Anidolic Daylighting Systems (ADS) (Scartezzini and Courret, 2002). They were implemented on different experimental test facilities (DEMONA daylighting test modules, LESO solar experimental building) in order to assess their luminous performance and users, acceptance at full scale (Altherr and Gay, 2002) (Linhart et al., 2010). The optimal integration of ADS with high efficacy light sources (CFL, LED) and efficient luminaries based on nonimaging optics in an office room was successfully achieved (Linhart and Scartezzini, 2011): it led to lighting power densities as low as 3 W/m2 (instead of 12-15 W/m2) together with improved occupants’ visual performance and comfort, as well as larger circadian light components compared to electric lighting (Linhart et al., 2009) (Linhart and Scartezzini, 2010). A bidirectional goniophoto meter, based on digital imaging techniques and showing significant advantages compared to conventional devices, was set up to assess the luminous properties of Complex Fenestration Systems (CFS) (Andersen et al., 2001) (Thanachareonkit at al., 2010). Combined to the visualization features of a novel CFS computer simulation software (Geronimo programme), it will lead to new analysis and design capabilities for advanced daylighting systems at EPFL (Kaempf and Scartezzini, 2011). The opportunity to investigate the psycho-physiological aspects of (day-)light, which affect the human health and well-being, was recently taken at EPFL through the creation of a “Post-Doctoral Fellowship in Daylighting and Perception” supported by the Velux Foundation (Switzerland). The more recent creation of a new interdisciplinary laboratory at EPFL, focused on “Performance-Integrated Design” and led by Professor Marilyne Andersen, a former PhD student at LESO-PB, will also contribute to strengthen the State of Union in Daylighting at EPFL by fostering daylighting design among students of architecture and professionals.
Jean-Louis Scartezzini was born in 1957 in Lausanne and graduated from the EPFL (Swiss Federal Institute of Technology, Lausanne) with a diploma in Physics in 1980. In 1986 he obtained a PhD in Physics for a thesis presented at the EPFL Department of Physics and written in part at Colorado State University in the United States. In 1991, Jean-Louis Scartezzini was nominated Professor in Building Physics at Geneva University, then, in 1994, he was nominated Professor at the Department of Architecture of the EPFL, where he heads the Solar Energy and Building Physics Laboratory. From 2002 to 2009 he furthermore headed the Institute of Infrastructures, Resources and Environment (ICARE) as well as the Doctoral School Programme Environment. He is the author of more than 200 scientific publications and member of several federal commissions and international work groups as well as associate editor of two scientific journals.