Abstract Body

Outdoor commercial lighting becomes an icon of urbanization. The excessive use of these commercial lighting in open space causes not only energy wastage, also the light trespass that impacts human health. More than 60% of the sky on earth is covered by light pollution, and about 80% of the world population suffers from its effect. Hence, many jurisdictions demand regulations and polices to control the light pollution. one of the most cities, Hong Kong, famed as Pearl of the Orient, is one of the most light affected cities.

This study aimed to assess light pollution quantitatively through measurement and numerical modelling. Site measurement protocols were developed and carried out in one of the busiest mixed commercial-residential area which also received the most complaints on the light nuisance) in Hong Kong. In this study, the illuminance level on the street was measured. In the shopping area (need to define), the average horizontal illuminance ranged from 44 to 1142 lux, with a mean of 223 lux. In the mixed-use area (need to define), a range from 14 to 556 lux and a mean of 130 lux were found. Findings showed illuminance levels are of 2.8-3.7 times (on average) in the shopping area and 1.6-2.2 times in the mixed-use one in excess of the International Commission on Illumination’s recommended levels.

The measured areas were also modelled with DIALux. This effort complemented the measurements by providing a means to increase the resolution on the light variation and to visualize light pollution in a 3D environment. The simulation results were verified by correlating the numerical model with measurements. The correlated model was exercised in a subsequent sensitivity study to predict possible outcomes with changing lighting pattern and light sources’ luminance level. This study serves as a pilot study in quantifying the light pollution issue in an urbanized area in order to eventually develop effective pollution management and policy.