Sunshine on a cloudy day
Globally, industrialised countries are replacing conventional incandescent lights with energy-saving fluorescent or white light light-emitting diode (LED) lighting. Aside from the limited aesthetics of such light, the lack of natural light, such as in countries with limited sunlight much of the year or in office buildings without many windows, is associated with conditions such as Seasonal Affective Disorder (SAD). Scientists sought to increase the quality of artificial illumination with EU funding of 'The sky light reconstruction in artificial illumination by means of solid transparent nanocomposites' (COELUX) project. Most previous efforts have focused on development of low-energy–consumption light sources with the same spectrum as that of the Sun. COELUX has provided a truly revolutionary solution based on the observation that the Sun does not provide its natural light only as a result of its spectrum but also due to subtle scattering effects related to the sky itself. Researchers developed novel nanocomposite materials produced in metre-size rigid panels and flexible films of unlimited length. When integrated with fluorescent and white light LED lighting, three lighting systems recreate the atmospheric scattering of sunlight at noon and one a sunset on a stormy day. The systems provide natural and atmospheric sunlight at any time of the day or night and in closed areas such as malls and metro stations. A modelling tool to simulate COELUX lighting systems and resulting environmental illumination will help create even more natural lighting scenarios. Finally, the team developed a lighting art performance with scaled-up technology for viewing by wide audiences at the 'Passion for Light' festival in Varenna, Italy. The show demonstrates the effects of sky, air and Sun on the visual perception of the surrounding landscape and buildings. COELUX has produced groundbreaking lighting technology inspired by the way the Sun's natural light is scattered by the sky. Novel nanocomposite rigid panels and flexible films are fully compatible with today's low-energy lighting solutions, transforming them from artificial illumination to the subtle colours of a sunset. Walking through the metro station may soon be a walk in the park.
