Light pollution caused by building façade lighting and signs attached to buildings

Pao Yue-kong Library Electronic Theses Database

Light pollution caused by building façade lighting and signs attached to buildings

 

Author: Lo, Chung-yun Juan
Title: Light pollution caused by building façade lighting and signs attached to buildings
Degree: M.Eng.
Year: 2011
Subject: Light pollution -- China -- Hong Kong.
Neon lighting -- China -- Hong Kong.
Lighting -- Environemntal aspects -- China -- Hong Kong.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Building Services Engineering
Pages: xiii, 110 leaves : ill. (chiefly col.), col. maps ; 30 cm.
InnoPac Record: http://library.polyu.edu.hk/record=b2451596
URI: http://theses.lib.polyu.edu.hk/handle/200/6244
Abstract: Light pollution is the unwanted energy wastage of artificial light sources causing sky glow, glare, and light trespassing etc. with the decreased visibility of natural astronomy creatures in the night sky. Sky glow is known as the effect of luminous background on the night sky reducing one's ability to view the celestial objects. Light trespassing is the intrusion of spill light to any area where it is unwanted. Glare is a short-term uncomfortable visual sensation caused by excessive and uncontrolled brightness. The investigation of the seriousness of the light pollution in Hong Kong in this dissertation was divided into two (2) parts: sky glow and light trespassing. Data of both parts were collected through site measurements. The site measurements were conducted throughout the entire academic year, i.e. from September 2010 to May 2011. While sky glow measurements were taken place in twenty (20) districts of various purposes, light trespassing measurements were carried out selectively in the residential buildings in two (2) commercial districts. Most site measurements were initiated after 2200 to prevent being affected by the sunset twilight. Simulation of the collected data was carried out as well. The raw data of light trespassing were analysed with a free downloaded software called Photosphere. Sky Quality Meter (SQM) was purchased and was used in sky glow measurements. It is a device that can measure the night sky brightness in units of magnitudes per square arc-second (mag arcsec⁻²). High Dynamic Range Imaging (HDRI) technique was used to measure the luminance of the building facade lighting and advertisement signs attached to buildings. It is a lighting estimation technique that captures wide luminance range within a scene by the multiple exposure photographs taken by the camera.
This dissertation was aimed at warning the public about the situation and raising their awareness on light pollution in Hong Kong, four (4) objectives were set to achieve: (1) to review the problem of light pollution in Hong Kong; (2) to review the parameters used to measure and control light pollution; (3) to survey light pollution problems in different districts in Hong Kong; and (4) to make recommendations of how to control light pollution. From the results of sky glow measurements, it was found that the night sky in Mong Kok of 13.05 mag arcsec⁻² night sky brightness with 100 times higher population density was brighter than Cheung Chau of 19 mag arcsec⁻² by over 130 times. Others districts were recorded to have night sky brightness ranged between 13 to 17 mag arcsec⁻². The overall average night sky brightness in Hong Kong was found to be 15.37 mag arcsec⁻², which was 302.72 times brighter than the 'perfect' dark sky for astronomical research of 21.6 mag arcsec⁻². On the other hand, the gravity of light trespassing in Sai Yeung Choi Street South, Mong Kok and Lee Garden Road, Causeway Bay, was commented with reference to the CIE 150:2003 limitations. The relationship of light trespassing with the level of the locations was observed to be inversely proportional. The lower the level of locations, the higher the illuminance recorded. This was probably due to the similar level of where the advertisement signs hung. The locations at higher level, which were further away from the signs, suffer less light trespassing from the light sources. Finally, recommendations for the general public, the professionals in lighting field and the government were proposed. For the public, tips of smart usage of lighting fixtures were given. The professionals should follow the reputable guidelines and standards of lighting designs and installations. A legislation framework on external lighting restrictions was drafted for the government after reviewing the experiences from other developed countries.

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