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LCQ1: Energy efficiency of public lighting systems

    Following is a question by the Hon Sin Chung-kai and a reply by the Secretary for Transport and Housing, Ms Eva Cheng, at the Legislative Council meeting today (November 21):


(a) of the respective types, luminous efficacies and average service lives of the luminous devices currently used in various kinds of public lighting systems in Hong Kong; and whether it has any plan to switch to more energy-efficient luminous devices; if it has, of the details; if not, the reasons for that;

(b) as a study on the adoption of light-emitting diode streetlights in Hong Kong is being arranged, of the details, including the timetable and completion date, of the study; and

(c) whether it has drawn up other measures to reduce the electricity consumption of public lighting systems; if it has, of the details?


Madam President,

(a) Currently, all public lighting installations used in Hong Kong are High Intensity Discharge lamps. Please refer to the table set out in the reply distributed to Members for details (Please refer to the attachment).

     With the advances in lighting technologies in recent years, the luminous efficacy and life span of lighting installations have been improved. To ensure continued improvement in the luminous efficiency of our public lighting system, the Highways Department (HyD) keeps in view product development, and regularly updates its specifications for supplies, adopts products with higher efficacy and replaces old and inefficient public lighting installations with high-efficiency installations.

(b) Much is being done in the research and development of the Light Emitting Diode (LED) road lights at a rapid pace. Generally speaking, the luminous efficacy of LED road lights is not higher than 50 lumen per watt, which is lower than that of the high pressure sodium lamps of 90-150 lumen per watt used for road lights in Hong Kong. An LED road light requires higher electrical energy and cost to achieve the same level of road illumination. Therefore, HyD has yet to consider putting LED road lights on trial. Nevertheless, in view of the recent claims of some manufacturers that they have developed new LED road lights with luminous efficacy exceeding 100 lumen per watt, HyD is liaising with the suppliers to see whether the new LED road lights can be used in Hong Kong. If high-efficiency LED road lights are successfully developed,  HyD will conduct trials to test their luminous performance, reliability and level of energy consumption. At this stage, HyD does not have a timetable for such trials as the development of LED road lights is not yet mature.

(c) In view of the improvement in the efficiency of lighting installations, HyD has put in place an ongoing replacement programme for high-wattage light-bulbs with those of lower wattage for road illumination, such as replacing 400-watt lights with 250-watt ones. On the one hand, road illumination can be maintained at the same level. On the other hand, the level of energy consumption can be reduced markedly.

     In addition, HyD has been carrying out energy saving pilot schemes, which make use of two types of electronic dimming appliances to lower luminance according to the time and the specific illumination conditions of the roads concerned. The pilot schemes compose of the following two stages:

     Stage 1 : HyD conducted the Central Dimming System Scheme as one of the energy saving pilot schemes between December 2005 and May 2006. The Electronic Ballasts for Dimming Scheme, the other pilot scheme, commenced in January 2006. In the first stage of the pilot schemes, road light luminance was lowered by 10% from switch-on time to midnight, by 25% from midnight to 5am, and by 10% from 5am to switch-off time.

     Stage 2 : In view of the needs for further testing the reliability and performance under further dimming for the central dimming system and the electronic ballasts, HyD launched the second stage of the pilot schemes in June 2007. During this stage of the pilot schemes, the road light luminance is lowered by 15% or 20% from switch-on time to midnight, by 30% or 40% from midnight to 5am, and by 15% or 20% from 5 am to switch-off time. The second stage of the pilot schemes will be completed at the end of this year.

     HyD will look at the information obtained when the energy saving pilot schemes are completed. A decision will be taken on the way forward in the light of the findings of the pilot schemes.

Ends/Wednesday, November 21, 2007
Issued at HKT 15:11


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