Method of Deriving Shaded Fraction According to Shading Movements of Kinetic Façade

Abstract

Exterior dynamic shading devices, installed on "kinetic façades", generate shaded areas of various shapes on windows according to the shape of the shading elements and the direction of their movement. The calculation of the shaded area is vitally important because it is directly related to the solar heat gain calculation process in building energy assessments. This paper dis-cusses a dynamic calculation method for deriving shaded fractions in consideration of the irregular shapes and unique movements of the shading elements in kinetic façades. The planar-polygon method was adopted for calculating accurate shaded areas on a window generated by irregularly shaped shade elements. To account for movements of the shading elements, the range of movement directions (i.e., rotating, sliding, etc.) was divided into β steps of equivalent intervals. Applying these two methods, a shaded area calculation tool for the kinetic façade was developed. Three movement directions of shading devices were chosen for calculating shaded area, and the values of shaded fractions for six kinetic façade types were derived for different façade orientations during the summer and winter solstices. Lastly, to simplify the detailed calculation method, estimation equations for two types of kinetic façade were derived from a trend analysis of the shaded fraction values. This study deals with both detailed and simplified methods (estimation equation) for deriving the shaded fraction. The detailed method can be a more accurate solution in deriving the shaded fractions generated by complex exterior movable shading devices. However, the simplified method can be adopted in the early design stages to review various shading devices within a brief duration of time.

Comparative Study on Computer Simulation of Solar Shading Performance with Heliodon and Artificial Sky

“…The resultant shaded area on a façade which is visually represented as shadows is essential in assessing the solar shading performance of shading devices. Calculations of shaded area cast by external shading devices are carried out using the cell method and the point method as described by Suji et al [26]. The cell method involves the subdivision of the shaded surface into scaled units of cells for quantitative estimation of shadows over each of the cells.…”

Optimizing Building Layouts for Proper Self-shading: A Computational Approach

“…Other tools were developed to cover extended details of shading, for example, Hashemloo et al [17] presents a method for designing a shading algorithm that utilizes visual comfort metric; it accounts for building specific local conditions. Choi et al [18] developed a shaded area calculation tool for kinetic façades in irregular building shapes; it derived shaded fractions on different movement directions and orientations. Yi et al [19] developed an advanced daylight model to simulate, evaluate and analyze the performance of dynamic shading device.…”

A Study on Multi-Objective Parametric Design Tool for Surround-Type Movable Shading Device

“…Research on movable sunshades has been attempted by various researchers, but has mostly consisted of research on control systems of movable sunshades such as venetian blinds, roller blinds, and shutters, as well as environmental performance [8][9][10][11][12][13]. The research on other forms of movable sunshades has been carried out to a limited extent due to the limitations of application and building performance simulation (BPS) tools.…”