A novel way of utilising Radiance-Matlab visualisation for façade design optimisation

This paper presents a parametric study for optimising façade design of a private office space. High dynamic range images are processed to document design conditions measured against established standards of visual comfort and needed light levels for circadian rhythm entrainment. Assessed lighting indices include luminance ratios, daylight glare index, vertical illuminance and its duration of exposure at eye level. An investigation is conducted based on the effect of a multitude of variables including façade orientation, seasonal variation, sky conditions, task type, glazing height and visible transmittance values. Results indicate that among the three head-heights tested, namely 1.2 m, 1.8 m and 2.4 m, the latter performed best in terms of discomfort glare and light exposure for an observer looking through the façade or at a computer screen. A visible transmittance of 50% is also recommended for year round conditions. Nevertheless, lower values may be required to prevent glare, especially on the south and west façades or for higher window-wall ratios.