PERFORMANCE OF LIGHT SHELVES FROM THE VARIATION OF THEIR INNER SURFACE

Abstract

Light shelves acts in the ligh distribution within the indoor environments and protecting from execessive brightness the areas close to the opening. Light shelves, under diverse shapes, positions and reflectances, are considered a great direct sunlight control strategy by the cientific comunity, improving as well the luminous comfort. In doing so, this article proposes to investigate, under the inner surface variation, the light shelves luminous performance. The analysis was performed through simulations in the software TropLux 8, for the following models: (1) environment without light shelf; (2) environment with horizontal ligh-shelf; (3) environment with 10º tilted ligh-shelf; (4) environment with 20º tilted ligh shelf; (5) environment with 30º tilted ligh-shelf. Were adopted the reflectances of “0,2”, “0,5” and “0,9” for the inner light shelves surface. The simulations took place for dynamic sky in Vitória-ES, from 8:0 0am to 5:00 pm on all days of the year, in the North and South orientations. The analysis metrics were the UDI (useful daylight illuminances) intervals and the DA (Daylight Autonomy), also using the NBR ISO/CIE 8995-1 as a reference. The results showed that the rising of the illumination level due to the increase in the light shelf reflectance (0,2 to 0,9), reaching up to 12% to South oriented light shelves and 35% for the North ones, keeping the tilt angle steady. In addtion, the results presents a decreasing in the illumination level due the inner surface tilt, reaching up to 18% to South oriented light shelves and 6% for the North ones, keeping the reflectance steady.