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

Ho-Jeong Kim,Hyeun Jun Moon,Chang-Seok Yang

doi:10.3390/su11247096

Abstract

This study presents a multi-objective parametric design tool for four-axis surround-type movable shading device using solar position tracking in Seoul, South Korea. In order to explore large numbers of possible forms of shades, generic algorithms are utilized with real-time simulation of the performative criteria such as solar radiation, daylight glare probability (DGP), and solar shielding rate on window surface. This study outlines a workflow using a multi-objective engine called Octopus that runs within Grasshopper 3D, a parametric design tool, in addition to environmental performance simulation plug-in Ladybug. The workflow utilizes a performance-based design tool, which allows the designer to explore, sort, and filter solutions, and visually compare alternative solutions in terms of energy saving and indoor daylight quality in order to determine the optimal form of shade changing its shape every one hour. The result of deriving and analyzing the optimal shade shape through the genetic algorithm proposed in this study is as follows: On the one hand, on the summer solstice, shade shapes with shielding areas of almost 100% should be derived to achieve the most effective reduction of the direct solar radiation. The proposed movable shading device reduced direct solar radiation by 52.40% and 57.20% in the south- and east-facing windows, respectively. On the other hand, in winter when solar heat gain is important, the absence of sunshade is optimal in terms of heating load. However, in order to improve the indoor light environment, it is confirmed that it is possible to derive a certain shape of sunshade according to the sun’s trajectory. On the winter solstice, the problem of glare arises from 10:00 to 15:00 in the south and 10:00 in the east. Therefore, the proposed four-axis movable shading device can be configured to have a minimum protrusion length satisfying DGP less than 0.35 in winter.

Highlights

Achieving sustainable goals in the construction sector requires buildings that are both energy efficient and able to improve the indoor environment for occupants
This study proposes a four-axis movable shading device for reducing direct solar radiation on window surface in summer and improving the light environment in winter considering the climate environment in Seoul, which is designed to identify the optimal sunshade shape at each hour
The various shapes of the shade, made using the parametric design rules described in Section 2.2.3, were derived each hour, and the evaluation results of three environmental performance criteria consisting of direct radiation, daylight glare probability (DGP), and shielding rate on windows were compared using the Octopus program

Summary

Introduction

Achieving sustainable goals in the construction sector requires buildings that are both energy efficient and able to improve the indoor environment for occupants. In order to improve the thermal vulnerability of the outer shell, many studies have attempted to improve energy demand performance by shielding the incoming solar radiation and applying external shade [2]. Horizontal shades are generally known to be most effective on the south side, and the protrusion length is estimated by considering the altitude angle of the sun. Azimuth is an important determinant for the vertical shade used on the east or west side where the solar altitude is low. In order to increase the shielding rate while shortening the protrusion length, it is effective to install the vertical fins at short intervals. Eggcrate-shaped shades combined vertically and horizontally can be applied irrespective of orientation by considering both solar altitude and azimuth. One disadvantage is that the natural light performance is degraded due to excessive shielding

Objectives

Methods

Results

Conclusion