Two common misconceptions about Lighting System:

    1.  Purchase price of a bulb is the real cost

People must also consider the operating costs over its lifetime. Lifetime costing can show that a bulb or tube that appears cheap can be much more expensive in the long run. Usually the initial cost is 10-25% while operational cost is 75-90% of life cycle cost In context of lighting it is the incandescent bulb which is cheapest but costly to operate.

    2.  Watt is a measure of light output. A 100 watt bulb is brighter than 60 watt bulb. Isn’t it?

Actually watts are measure of electrical consumption and lumens are measure of light output. If our goal is buying light (and not electricity) then we should buy light which gives more lumens and consumes least wattage.


How to save?

The design, control and automation of large building lighting system is a complex process. These goals can be achieved by an intelligent monitoring system with automated features. Automated features means the control system reads, understands, and is ready to adapt to external conditions, needs and habits of occupants. EnergyLogicIQ – Energy Intelligence Platform’s primary goal is to work in unison with the automation of a client’s existing Building Management Systems (BMS).

Read about the saving potentials of efficient lighting system:


Basic Terminologies in Lighting System:

  1. Flux emitted by lamp (Lumens): Measure of the total amount of visible light emitted by a source
  2. Luminous Efficacy (Lumens / Watt): Measure of how well a light source produces visible light. It is the ratio of luminous flux to power
  3. Illuminance (Lux): Equals to one lumen per square meter
  4. Colour Rendering Index: Ability of a light source to reveal the colors of various objects in comparison with an ideal light source


Types of Lamps

Type Wattage Lumens Efficacy CRI     
Incandescent 100 1380 14 90
Fluorescent 40 2400 60 60-90
Mercury Vapor 250 13500 54 70
Sodium Vapor 250 27000 108 80-90
Metal Halide 250 17000 68 70-90
CFL 20 1200 60 70-90
LED 20 2000-2500 100-120 80-90



Key points for Energy Saving in Lighting

1. LED are most energy efficient

  • High color rendering - 85
  • High Efficacy 120 lumens/W
  • Life of 50,000 hours
  • Ideal choice for new projects – can be used in Control Room, Lab, Office etc

2. HPSV lamps are good for areas like Godowns, Storage Yards, Flood Lighting and Street lighting

3. Use a lighting distribution software to estimate location and height of lighting. (Ask your lighting vendor to demonstrate this are per ASHRAE standards)

4. Use a dedicated lighting transformer with different tap settings that drop the voltage to 205-210 volts.

  • Most lamps have rating of 210 Volts
  • Reduction in voltage by 11% drops power consumption by 20%
  • Causes insignificant drop in illumination level (<2%)
  • Increases life of lamps

5. Make maximum use of natural light

  • Use combination of day light and lamps
  • Use natural light controlled by motorized blinds
  • Sensors to detect natural light and switch on-off artificial lighting
  • Provide smooth transition from natural light to artificial light
  • Use timer control switches for outside lighting system

6. Use occupancy / movement sensors, dimmer control systems wherever required. Most ideal locations for using occupancy sensors are lobbies, meeting rooms and washrooms.

7. Proper grouping of lights (panel) and lighting control system

8. Consult IS 3646 and ASHRAE lighting standard


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