Natural light from a wall in buildings: experimental analysis of the ventilated illuminating wall performances

The Ventilated Illuminating Wall (VIW) is a technological device set up by the authors. It is a passive solar system. In buildings without direct interface to outdoor, it is able of providing natural light and air for indoor ventilation. The authors built a 1:1 scale prototype of the VIW in the laboratory of Technical Physics of the INGEO Department of Pescara. It consists of a multilayer structure applied on a window of the perimeter wall of the building. Daylight is captured by a horizontal glass surface and redirected into the system thanks to the reflections by a highly reflective film applied on the internal walls of the VIW. The reflective film is the same used in the light pipe technology. In this paper, the authors show a technological description and the building steps of the device and the results of an experimental analysis on daylight performances. The data reported in this work regard both winter and summer conditions, and they can be considered satisfactory in every situation. Under overcast sky, the internal illuminance trend is similar to the external one, particularly in positions close to the system, and the influence of the VIW on internal illuminance is on average of about 2 m. Under Clear sky with sun, the system has a higher efficiency, thanks to the intense reflections, which cause some peak values of illuminance. In general, the VIW is able to furnish a significant high-quality natural light contribution to the room. It is particularly suitable in museums and exhibition rooms with large plant area, because it provides a soft distribution of light.