Following is a question by the Hon Chan Kin-por and a written reply by the Secretary for Transport and Housing, Professor Anthony Cheung Bing-leung, in the Legislative Council today (April 26):

Question:

     At present, the majority of the around 146 000 street lamps in the road lighting systems across the territory are high pressure sodium lamps. After conducting a trial scheme in 2009, the Highways Department advised that although low- and medium-wattage light emitting diode (LED) lights were energy-saving due to better colour rendering, the wider use of LED lights in the road lighting systems was not cost effective as the prices of LED road lights meeting the necessary certification were very high. Regarding the use of LED lights in the road lighting systems, will the Government inform this Council:

(1) of the respective electricity expenditure incurred in each of the past two years by the Government on street lamps;
 
(2) given that the prices of LED lights have dropped further in recent years, whether the authorities have reassessed the cost effectiveness of using LED lights in the road lighting systems; if so, of the results; if not, the reasons for that;
 
(3) given that LED lights are used by quite a number of overseas countries and the Mainland in some of their road lighting systems, whether the authorities have made reference to their relevant experience; if so, of the details; if not, the reasons for that; and
 
(4) whether the authorities have plans to use low- and medium-wattage LED lights in those road lighting systems with lower lighting requirements; if so, of the details and timetable; if not, the reasons for that?

Reply:

President,   
 
     The public lighting system is an auxiliary facility for road network. Public lighting system includes carriageway lighting, footpath lighting, cycle track lighting, underpass lighting, high-mast lighting, high-bay lighting at public transport interchanges, footbridge and subway lighting, gantry sign and roadside directional sign lighting as well as traffic bollards, etc. 

     At present, high pressure sodium (HPS) lamps of high efficacy are widely adopted in road lighting system of Hong Kong, of which the low wattage (Note 1) ones have an efficacy of about 90 lumen (Note 2) per watt while the high wattage ones have an efficacy of 150 lumen per watt, all exceeding the efficacy of the household compact fluorescent lamps at about 60 lumen per watt.

     Since LED road light products became available in the market, the Highways Department (HyD) has been monitoring the technical and market development of these products. The LED road lighting technology earlier was still at the initial stage of development. LED road light products available in the market had diverse qualities and the prices of the certified LED road lights that satisfy the required design standards were much higher than the HPS lamps. As such, the launching of the LED road light replacement scheme at that time was not cost-effective. Nevertheless, HyD has continued to monitor the technical and market development of LED road lights, and carry out various trial schemes for LED road lights to provide technical basis for the extensive use of LED road lights in the future.

    My reply to the four-part question raised by Hon Chan Kin-por is as follows:
 
(1) The respective expenditures on the electricity of road lights by HyD in the territory in 2015 and 2016 were about $100.56 million (with the one-off special fuel rebate of about $3 million provided by the CLP Holdings in 2015 deducted) and $104.13 million.

(2) and (3) Since 2009,  HyD has been installing LED road lights in different places over the territory as field trials and so far 171 LED road lights have been installed. The findings of the trial so far have confirmed that low- and medium-wattage LED road lights are better than low- and medium-wattage HPS lamps in terms of energy saving, colour rendering and reliability. As regards road sign lighting, HyD installed LED lights for 3 gantry signs and roadside directional signs lighting in 2015 as a trial. The results indicated that LED lights allow more uniform illumination and are about 70 per cent more energy saving than the existing Ceramic Discharge Metal Halide floodlights. For subways, HyD carried out trial installation of LED tubes in 20 subways in 2015 and 2016. The results indicated a saving of about 20 per cent of electricity as compared with traditional T8 fluorescent tubes and a satisfactory illumination. 
 
     Apart from the experience gained from the above trial schemes, HyD has all along kept in touch with the authorities in overseas countries and the Mainland to gather information in adopting LED road lights from other places and to make reference to their experiences. In order to keep in pace with the technical and market development of LED road lights, HyD has received more than 20 groups of representatives of road lights manufacturers from the Mainland and overseas countries in the past two years. In addition, representatives of HyD visited London and Mainland cities like Zhuhai, Shanghai and Ningbo in end 2016 and early 2017 to exchange ideas with the institutions of lighting professionals and road lights manufacturers there. 
 
     Upon review, HyD is of the opinion that LED road light technology has matured considerably over time. In light of the higher efficacy of the medium- and low-wattage LED lights, which has already transcended that of HPS lamps, coupled with the significant drop in LED lights prices, HyD agrees that it is now an opportune time to use LED lights in the public lighting system and HyD will commence the LED road lights replacement programme.
            
(4) Taking into account the life expectancy of existing road lights, HyD will replace the medium- and low-wattage HPS lamps for local distributors, footpaths and cycle tracks with LED lights progressively. The concerned replacement works have already commenced in the 2017-18 financial year. HyD will continue to use high-wattage HPS lamps as they still maintain a competitive edge in terms of their technology, quality, efficacy and price. HyD will continue to monitor the development of high-wattage LED road lights and explore their application in due course. Apart from replacing the medium- and low-wattage HPS lamps, HyD will also replace 4 500 gantry sign and roadside directional sign floodlights in the coming five years and 10 000 sets of T8 fluorescent tubes in footbridges and tunnels with LED lights in the coming seven years.

Note 1: High pressure sodium lamps used for public lighting are of power ranging from 50 to 600 watts, depending on the illumination needs.

Note 2: "Lumen" is an international unit for measuring luminous flux, and is a luminous power related to the sensitivity of the human eye. One lumen of light per square metre equals to 1 lux of illumination. A candle emits about 12.6 lumen while a 100-watt incandescent  lamp (i.e. the tungsten filament lamp commonly used in households) emits about 1 300 lumen.

Ends/Wednesday, April 26, 2017
Issued at HKT 15:00

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