Paper Conference

Proceedings of BSA Conference 2017: Third Conference of IBPSA-Italy


Selecting Roller Shades Properties Based on Glare Mitigation, Energy Performance and Connection to the Outdoors

Iason Konstantzos, Athanasios Tzempelikos

Abstract: Visual comfort is one of the main priorities in designing working and living environments. Several indicators have been developed to quantify the degree of visual discomfort; however, there is a lack of studies in spaces with roller shades on the windows, commonly used in North America. Roller shades transmit direct and diffuse daylight and therefore their effect on visual comfort is complex. A recent study with human subjects proposed two alternative approaches in quantifying visual discomfort for the case of roller shades, based on (i) a modification of the Daylight Glare Probability (DGP) and (ii) an index based on the direct and the total portion of vertical illuminance on the eye of the observer. This paper uses a methodology based on the newly developed indices in an inverse way in order to propose suitable ranges for optical properties of the shade fabrics, in terms of openness factor and visible transmittance. A complex fenestration model that calculates the angular beam–beam and beam– diffuse shading optical properties is implemented within an advanced hybrid ray-tracing and radiosity daylighting model. Then, the concepts of annual discomfort frequency (Chan et al., 2015) and View Clarity Index (Konstantzos et al., 2015b) are used as a basis for the extraction of ranges of shade optical properties with respect to glare mitigation, energy performance and connection to the outdoors, for different sets of input parameters (location, orientation, glazing visible transmittance and distance from the window). The use of these extracted ranges can help architects select the most suitable shading products for their designs, minimizing glare complaints with the minimum cost in terms of lighting energy use and connection to the outdoors.
Pages: 539 - 546