Daylighting characterstics of existing double-skin façade office buildings

Double-skin façade (DSF) buildings have been developed and used in both new and renovated buildings to increase human comfort and decrease energy consumption. Daylighting in DSF buildings has received less attention compared ventilation strategies. This paper aims to evaluate the daylighting characteristics of 12 existing DSF systems that are exposed to different climates by using the IES simulation software. The protocol was applied to south-facing models under overcast sky conditions and was implemented under different outdoor illuminance. Different designs of DSF systems significantly affect the indoor illuminance values inside the office. At the office entrance, the indoor illuminance values are free of glare. All DSF models fail to meet the standard indoor illuminance requirement of at least 200 lx within 75% of the office space. Among all the DSF models, the percentage of the office space covered with at least 200 lx are found in the range of 40-68%, 13-52%, and 5-30% at an outdoor illuminance of (19,000, 12,000, and 6000) lx, respectively. At an outdoor illuminance of 19,000 lx, the studied DSF systems from subtropical climates show the best daylighting characteristics and are potential subjects for further optimization. Based on the assumptions of this case study, daylighting analysis shows that the existing 12 DSF systems do not follow daylighting strategies.