Light level, visual comfort and lighting energy savings potential in a green-certified high-rise building

Abstract

Over-illumination and poor distribution of light are among the factors that lead to visual comfort problems. This paper reports on the outcomes of a post-occupancy survey that evaluated visual performances in a highly glazed green building and the perceptions of the tenants towards their visual environment. Measurements of light source luminances and work area illuminances were carried out using calibrated equipment and survey forms were distributed to the tenants. The degree of perceived discomfort glare at the studied areas was calculated using the field data collected. The results show that although the indoor spaces were generally well lit from 10am to 3.30pm using natural daylight, discomfort glare was predicted at workstations near to the window area. However, most of the tenants were satisfied with the perceived lighting levels during the survey, possibly owing to the use of internal curtain blinds when they experienced discomfort glare. The high illuminance in the open-plan office compartments was a major concern which necessitated the use of shading devices to prevent visual discomfort. While improved lighting energy management can be achieved via reducing the dependency on artificial light fittings, more studies on the costs incurred to further enhance lighting energy efficiency and the interior visual environment using newer glazing materials, lighting technologies and control strategies are required.