Street Lights

Project Background:

 The electricity consumption in municipal sector is increasing rapidly over the last few years. The goal of energy management must be on provision of services like drinking water & street lights with the least cost and least environmental effect. Hence corporation,   has appointed an ESCO to implement street light energy efficiency project as per rule.  The  ESCO conducted an investment grade energy audit. Based on   appropriate plans  that would lead to reduction in energy consumption. During the project implementation, the ESCO has converted the conventional lamps into LED lamps lights with ESM equipments. This projects evolves with    street light monitoring devices which enables to monitor the energy consumption and Individual Lamp monitoring devices for important roads at an instant.

Hence Corporation desires to take this implementation process to next level and has come up with a solution for reducing the energy consumption due to street lights and hence to reduce the energy expenses and modernizing the entire street lighting infrastructure with the state-of-art technologies.


The basic objective of this project is to provide meet the increasing street light demand of the Tiruppur City Municipal Corporation, improve the overall energy efficiency of the Corporation’s street lighting system which could lead to substantial savings in the electricity consumption without compromising the quantity and quality, thereby resulting in cost reduction/savings for the Corporation. Other objectives of the project are,

  • The maximize the energy savings to be achieved by replaced all existing conventional lamps with the energy efficient LED luminaries and ESM equipments. 
  • LED lamps provided as IS standards
  • Luminous intensity lamps provided to category of roads accordingly,
  • Measuring System equipments installed to verify the Energy saving instantaneously
  • Monitoring station facilitate with advanced O & M approach
  • Modernizing the street lighting infrastructure as per the BIS standards

Carbon Emissions:

Power generation accounts for about one-quarter of total emissions of carbon dioxide, the main culprit in global warming. Electricity generation using carbon based fuels is responsible for a large fraction of carbon dioxide (CO2) emissions worldwide. Coal contains more carbon than oil or natural gas fossil fuels, resulting in greater volumes of carbon dioxide emissions per unit of electricity generated.

Hence carbon footprint has a greater impact on whole mankind. In India, street lights being 5% of total electricity consumption, contributes a considerable share towards the carbon emissions. Street lights being the one of the basic amenities the demand for the same increases day to day with the rapid urbanization. The increasing street light requirement needs to be met out with alternate efficient methodology, where both the public need and carbon emission reduction should not be compromised.

Existing Street lighting system:

            Present street lighting system of Tiruppur City Municipal Corporation comprises of 35213 nos of lamps have various lamp types and wattages. These lamps are fed by 2500 plus feeding points among which more than 88% of feeding points are single phase and the remaining are of three phase. These feeding points controlled by Automatic Street light and voltage controllers which are under Centralized Control and Monitoring Center (CCMC). The Corporation’s lamp types falls under 3 major categories,

These lamp types are further divided into,

S.No. Type of lamp Quantity
1 Sodium Vapour Lamp 130W 735
2 Sodium Vapour Lamp 220W 4107
3 15 W LED 18617
4 20 W LED 5819
5 40  W LED 1320
6 72 W LED 465
90 W LED 763
8 120 W LED 2393
9 150 W LED 166
10 200 W LED 828


Distribution pattern:

            Among the total lamps of 35,213 numbers, energy efficient lamps contribute 31436(86%) numbers and remaining 4.814(14%) numbers are conventional energy efficient lamps. However, 14% of conventional lamps contribute 5% of load sharing whereas 86% of energy efficient lamps contribute 95% of total load.

Photometric terms :

Luminance (at a Point of a Surface and in a Given Direction) — The luminous intensity per unit projected area of a surface. If a very small portion of a surface has an intensity I candelas in a particular direction and its orthogonal projection (that is, its projection on a plane perpendicular to the given direction) has an area D, the luminance in this direction is I/D candelas per unit area. The usual unit is the candela per square metre (cd/m2).

Luminous Efficacy — The rate of converting electrical energy into visible light is called “luminous efficacy” and is measured in lumens per watt. The types of lamps commonly used for street lighting are listed in the table below with brief descriptions (for comparison with existing lights, these values shall be taken). The luminous efficacy and total lumen output of the proposed lamp should be more than that of the lamp being replaced. The energy saving potential through replacement of lamps will be calculated on the basis of the total lumen output of the luminary.

            Advantages of installing LED Lights:

  • Low power consumption and long and predictable lifetime: The lifetime of LED street lights is usually 10 to 15 years, three times the life of current technologies adopted. The much less frequent need to service or replace LEDs means low maintenance cost.
  • Small package size and weight
  • More accurate color rendering: The color rendering index is the ability of a light source to correctly reproduce the colors of the objects in comparison to an ideal light source.
  • Quick turn on and off: Unlike fluorescent lamps, which take time to heat up once switched on, LEDs come on with full brightness instantly. Unlike mercury vapor, metal halide and sodium vapor lamps (commonly used in street lighting), LEDs do not have a problem restarting immediately (hot ignition) following a brief power failure or inadvertent turn off.
  • RoHS compliance: LEDs don’t contain mercury or lead, and don’t release poisonous gases if damaged.
  • Less attractive to nocturnal insects: Nocturnal insects are attracted to ultraviolet, blue and green light emitted by conventional light sources.
  • Fewer electrical losses: All other types of lighting (except incandescent) require ballasts, additional electronic and/or electromagnetic components, in which some power is consumed.
  • Optically efficient lighting equipment: Other types of street lights use a reflector to capture the light emitted upwards from the lamp. Even under the best of conditions, the reflector absorbs some of the light. Also for fluorescent lamps and other lamps with phosphor coated bulbs, the bulb itself absorbs some of the light directed back down by the reflector. The glass cover, called a refractor, helps project the light down on the street in a desired pattern but some light is wasted by being directed up to the sky (light pollution). LED lamp assemblies (panels) do not require reflectors and can be designed to provide the desired coverage without a refractor.
  • Higher light output even at low temperatures

Installing Streetlight Controllers

The Streetlight controllers are to be installed in each service connection/ switching point where it is not available to control and monitor the streetlights automatically. The newly proposed / to be converted energy efficient lamps are to be integrated with existing street light controllers, wherever available.

The main purpose of installing the Streetlight Controllers is

  • Remote ON/OFF of lights by GPS/Time based switching
  • Wireless Monitoring and controlling of each service connection through GSM/GPRS technology

Technical Specifications

Energy Efficient LED Lamp Fittings

  • The light source will be of white LED type and be compliant to IEC standards.
  • Should be compliant to LM80 IES: Approved method for measuring Lumen Maintenance of LED light sources and LED lumen depreciation time. LM-80 test certificate is to be submitted.
  • Luminous efficiency of the LEDs should be more than 115 lumen/watt.
  • Rated Lamp life should be 50,000 hours at soldering point temperature of 85C and at a
  • Power factor should be greater than 0.90 and Lamp housing should be IP65 compliant.
  • Electrical efficiency should be greater than 85%.
  • After pole mounting, lux levels to be maintained as per IS1944 standards.
  • Luminary should be fitted with gasket and accessories for weather proof and insect proof operation.
  • Temperature rise of Heat Sink shall not be more than 20C for 48 hours continuous operation.
  • LED lamps should be tested in a NABL (National Accreditation board for Testing and Calibration Laboratory) accredited laboratory.
  • LED make: CREE,GE, Philips, Nichia, Osram.

Streetlight Controllers           

  • Device capability of scheduling the on/off timings of lighting control switchgears based on the available annual sun-rise and annual sun-set timings.
  • System capability to capture and provide following parameters at variable time-intervals and live data collection of various electrical parameters:


  • Special emergency on/off facility with wireless control.
  • GPRS/GSM modem used should be a Dual-band modem with power consumption less than 3 watts.
  • Energy Meter with ISI marking is to be used for power measurement. Class 1.0 accuracy or better energy meter to be used.
  • In cases where the Streetlight Controller is used in conjunction with Individual Lamp
  • Monitoring (ILM) devices, the Streetlight Controller should be capable of acting as a RF Data Concentrator so as to be able to communicate with all the ILM devices of that switching point.

Conversion proposed:

Selection of Lamp type:

In line with the criteria referring to the selection of lamp type and wattage, illumination level requirement (based on road type) has been given at most importance. Following factors are taken care while deciding the same,

            Roads with dense traffic and those which are the arterial roads are termed as ‘A’ class roads (A1 and A2).These roads needs higher illumination levels, hence fittings with high lumen output are considered. Currently these roads, mostly, are illuminated by T5 lamp fittings. These lamps due their ageing and poor lumens per watt output, provides 6528 lumens output, which is insufficient for the A class roads. Hence 120W LED fitting providing 13,800 lumens are proposed for such roads.

            On the other hand roads with lesser traffic and those roads in commercial and residential   are termed as ‘B’ (B1 and B2) and ‘C’ class roads respectively. It was observed some of these roads are provided with highly illuminating lamps resulting in light pollution in those areas. Hence fittings with less illumination are proposed. They solve two purposes,

  • Reduce energy consumption
  • Eliminate light pollution

The below table provides the details of how new energy efficient lamps are selected against the existing conventional lamps,

Existing Lamp type Total Output Lumens of Existing Lamp

(in lm)

Proposed Lamp type Total Output Lumens of the proposed Lamp

(in lm)

Justification for choosing the Energy Efficient lamp wattage
SVL 130W 11040 72 W LED 8280 7500 lumens output is sufficient for the ‘B2’ type road whereas the existing conventional lamps produce more lumen output resulting in light pollution
SVL 250W 12800 90 W LED 10350 10000 lumens output is sufficient for the ‘B2’ type road whereas the existing conventional lamps produce more lumen output resulting in light pollution.


Based on the above considerations, LED lamps are proposed as replacement for the conventional inefficient lamps.

* HPSV 130W and 220W   luminairies  are already provided with the ESM equipments for Energy saving under the PPP mode ESCO project. These  conventional lamps which are to be retrofit. 

Need for new (additional Lamps):

            Tiruppur being a growing city, the boundary of residential and commercial areas keep increasing day by day. As a result of which there is a growing demand for street lights simultaneously. To meet out the requirement the corporation provided the additional lamps under the smart city mission  adopted the following methodology.

20W energy efficient lamps:

            These lamps are proposed in the newly developed residential and tiny knitting units interior  areas of the city, where the roads are of type ‘C’.

72W energy efficient lamps and 90W energy efficient lamps:

            These lamps are to be installed in the arterial roads which are connecting NH and SH roads and commercial and industrial transport   of vehicular traffic importance. In general these roads falls under category ‘Type B’ of classification of roads.

120W energy efficient lamps:

            These lamps are to be installed as centre median lights in the ‘Category A’ roads which are connecting business cities in the corporation limit and are not covered by street lights.

200W energy efficient lamps:

            These lamps are a part of high mast lamps which are to be erected at the crowded main junctions within the corporation limits.

New Lamps and ESM equipments are Provided under smart city mission:

S.No Lamp Type Quantity
1 20 W LED Lamps 2397
2 72 W LED Lamps 220
3 90 W LED Lamps 150
4 120 W LED Lamps 416
5 200 W LED Lamps 80
6 ESM equipments (Street light controllers) 239
7 ILM (Individual Lamp Monitoring) devices 3263
Total lamps 3263

 It is evident that even after the increase in lamp quantity; there will be a considerable reduction in the load demand after the implementation process. The lamp quantity has increased from 31,950 to 35,213 whereas the connected load has decreased from around 2.40 MW to 2.05 MW.

The energy efficient lamps which will be replacing the existing convention lamps or energy efficient lamps which will be installed newly will be integrated with existing street light monitoring controllers. New street light controllers will be installed wherever required.

  • In addition to this the street light controllers in high mast lights are proposed with dual timers – one for switching ON/OFF the entire high mast lamps, another for cut off of partial load during off peak hours. This will result in additional 10% savings in those services.

Operation and Maintenance:

Operation & Maintenance of newly erected ESM Equipments: The contractor shall operate and maintain the new ESM Equipments up to the year of  2024.


Project Cash flow statement:

Return on investment from smart city project


Year Implementation period (2018-19) 2019-20 2020-21 2021-22 2022-23
Capital investment* 611.12 504.62 389.60 265.38 131.22
Energy savings per annum 128.70 128.70 128.70 128.70 128.70
O&M cost savings per annum** 15.18 15.18 15.18 15.18 15.18
Return of investment 467.24 360.74 245.72 121.50 -12.66

Savings achieved  per annum from PPP mode scheme:


Assured guaranteed energy savings  –   42.68 %

Assured O & M expenditure savings  –  15.67 %

Name of the


Year of Implementation  Saving amount in Cr. 2017-18 Saving amount in Cr. 2018-19 Saving amount in Cr. 2019-20 Saving amount in Cr. 2020-21
PPP Mode 2016-17 2.38 Cr 2.87 Cr 2.57 Cr Under scrutiny
Energy saving in % 46.27 % 43.88 % 42.87% – do –
O&M saving in % 15.73% 15.76% 15.72% – do –