IMPROVEMENT OF ENERGY EFFICIENCY IN THE STREET LIGHTING SYSTEM OF THE COLOMBO CITY H.K. ILLEPERUMA H.R.P. WANNIARACHCHI SRI LANKA ENERGY MANAGERS ASSOCIATION H.H.D. NANDASENA COLOMBO MUNICIPAL COUNCIL

Contents 1.Colombo City – Statistics 2. Present Street lighting system- Colombo City 3. Present Street lighting system-Selected Area 4. Findings of the Survey 5. Possible Energy Saving Measures 6. Implementation Plan

Statistical Data of Colombo City §Area37 sqkm §Population 1.7 million §No of Retail Customers120,000 §No of Bulk Customers 1200 §Total Electricity Sales790 GWh/year §Electricity Units billed for Street lighting10 GWh/year

§Electricity Distribution System is operated and maintained by Ceylon Electricity Board §Street Lighting System is operated and maintained by Colombo Municipal Council (CMC) under 6 districts Colombo City

250W SVMain Roads 250W MV and OthersBy roads 150W SVBy roads /Footpaths 125W MVFootpaths/Gardens Present Street Lighting System Recently CMC has adopted following basis in installation of Street Lights

§There are about 12,000 Street Lamps in the CMC Area §834 MWh of energy is consumed per Rs 7.80 per unit, results in a monthly bill of Rs 6.5 million Present System Contd..

§Operation of Street Lights l 30% Automatically using photocells l 70% Manually §Electricity Supply to Street Lights are from both overhead and underground lines

Present Street Lighting System- Kirulopane Area Number of lamps in the District 4 (Kirulopane Area) W SV 150W SV 250W SV 125W MV 250W MV

In Study Area.... Classification of Roads 1. Main roads with high vehicular traffic 2. Roads connecting to main roads with substantial vehicular traffic and pedestrian traffic 3. Roads leading to residential areas and terminating.

Details of Street Light Luminaries in the Study Area Robert Gunawardana Mw and Balapokuna Road connect to other main roads, carry considerable vehicular traffic.

Findings of the Survey §Luminaire Mounting Height & Height of Pole §Spacing of Lamps & Span of Poles §Luminaire Position §Switching Systems §Lumen output of Lamps & Type of Lamps §Maintenance of Street Lighting System

§Use high efficacy bulbs & ballast §Use more efficient luminaries §Timely Switching on/off §By proper lighting design §By switching off some lights during low traffic periods §By dimmer units, reducing luminance during low traffic hours §Proper maintenance scheme. Possible Energy Saving Measures

§Use high efficacy Lamps & ballast l Replacement of Mercury Vapor lamps with High pressure Sodium Vapor lamps. 125W MV ----> 70W SV 250W MV ----> 110W SV §This can be done in two ways l Replace complete fitting for very old lights l Replace only the bulb & ballast for fairly new lights

§Replacement of Mercury Vapour Lamps with Sodium Vapour Lamps l 250W MV Lamps 110W SV Lamps DescriptionStudy Area (14 lamps)District 4 (385 lamps) InvestmentRs.73,500Rs.2,021,250 Annual Saving Life Cycle Saving Rs.66,961 Rs.293,4912 Rs.1,841,440 Rs.8,068,830 Pay-back Period13 months

125W MV Lamps 70W SV Lamps §Can be installed along roads in residential areas §Recommended Mounting height is 6m at 30 to 35 m intervals §In future all the new installation in the residential areas should be with 70W SV

Comparison Between 125W MV & 70W SV 125W MV70W SV Lumen output Annual energy consumption548 kWh307 kWh Annual energy costRs. 4,271Rs. 2,391 Life cycle energy costRs. 23,400Rs. 13,104 Cost of fittingRs. 4,600Rs. 4,500 Life cycle costRs. 28,000RS. 17,604 Life cycle Saving Rs. +10,396

Comparison between the replacement of 125W MV complete fitting and replacement of 125MV bulb & ballast only. Complete fitting Bulb only Annual energy saving241 kWh Annual energy savingRs. 1,879 Life cycle energy savingRs. 10,296 InvestmentRs. 4,500Rs. 2,000 Payback period29 months13 months Life cycle savingRs. 5,796Rs. 8,296

Possible Energy Saving Measures §Timely switching on/off §Fixing of photoelectric cells for automatic operation of lamps (for circuits & individual lamps)

Costs & Benefits of the Proposal DescriptionStudy AreaDistrict 4Colombo City Investment Rs.86,400Rs.780,000Rs.5,040,000 Annual Saving : Energy Labour Total Saving Rs.15,374 Rs.73,000 Rs. 88,374 Rs. 170,229 Rs.511,000 Rs.681,229 Rs. 1,106,060 Rs.3,285,000 Rs.4,391,060 Payback Period 12 months14 months

§The level and uniformity of luminance along a road depend on several factors l Lumen output of the light source l Luminaire distribution l Mounting height l Luminaire position and l Spacing l Installation arrangement Possible Energy Saving Measures By proper system design

Luminaire Mounting Height & Height of Pole

Spacing of Lamps §It is required to maintain equal distances between street lamp poles. §Most effective distance is 35m to 40m. § It is not economical to erect additional poles for street lighting to maintain the equal spans in the existing system.

Overhang & Angle of Tilt §Overhang and Angle of tilt vary with the following l Width of road l Lumen Output of the lamp l Height & Spacing of the poles §The most effective angle of tilt is 5 to 10 degrees and overhang is 0.75 to 1.5 meters, depending on the width of the road.

Maintenance Scheme for Street Lighting §Improve the light levels in the city and gradually the wattage of the lamps could be reduced. §Provide benefits not only the energy conservation but also the other benefits in terms of public safety, security, convenience and comport during darkness. §Maintenance program twice a year. Possible Energy Saving Measures

Maintenance of the Street Lighting Should Include.... §Luminaire Maintenance l luminaire cleaning is required to maintain designed lighting levels. l loss of lumen output of light sources due to normal aging §Support Structure Maintenance §Electrical Distribution and Control System Maintenance §Pruning of trees which disrupt light distribution

Implementation Action Plan

Thank You !