The unique urban environment of Hong Kong presents designers and students alike unique challenges. Firstly, rules of thumb not longer apply. Secondly, few design tools, mostly developed for low-rise open sites could be used. Advanced computational lighting simulation software could be used to address the design need of information. This study examined the accuracy of two daylighting simulation software: Lightscape and Desktop Radiance, under heavily obstructed urban conditions in Hong Kong. In addition, it evaluates the performance and usability of these two software packages from the designer's perspective. It can be reported that, with due care, both software give reasonably accurate results. However, from the designeris perspective, the look and feel of the two software, and the need for a priori knowledge of lighting design determine their eventual adoptability.