Potential advantages of a multifunctional complex fenestration system with embedded micro-mirrors in daylighting

摘要

Proper daylighting designs in interior spaces may reduce the energy costs of electric lighting and improve the productivity of occupants. This paper reports the potential advantages of a multifunctional complex fenestration system with embedded micro-mirrors in daylighting by simulation. The system consists of a polymer layer with an array of embedded parabolic micro-mirrors, which was attached to a glass pane of glazing. By appropriate geometrical design, the embedded micro-mirrors may combine the function of keeping a clear view through the glazing due to the microscopic size of the embedded mirrors, and improving daylighting quality and quantity because of the redirection of daylight by micro-mirrors. In order to fully explore the potential advantages of the daylighting system with embedded micro mirrors, three configurations were investigated: micro-mirrors in the upper third of a double glazing, micro-mirrors in the upper two-thirds of a double glazing and micro-mirrors in the whole glazing. Metrics based on illuminance, uniformity, glare and directivity were used to assess daylight performance for a south-facing fa ade in Lausanne (46 degrees 30'N and longitude 6 degrees 37'E), Switzerland. Compared with a standard low-e double glazing, the daylighting system with micro-mirrors could induce more daylight in the rear of a room and improve the uniformity of the daylight distribution. By integrating micro-mirrors in the upper two-thirds of the glazing, the risk of glare was reduced for a sightline parallel to the glazing on the spring equinox and on the winter solstice. For the case with micro-mirrors in the whole glazing, the directivity of daylight along the depth of the room was significantly improved from the harsh range to the preferred range at noon, suggesting a comfortable visual situation. (C) 2016 Elsevier Ltd. All rights reserved.