The practice of turning off lights when not in use has been used as an energy-saving measure since quite some time. It is pretty effective, although there are some studies that suggest that using energy-efficient lights is far more effective than turning off lights. The amount of electricity savings by turning off lights depending on the type of light used.
A typical incandescent bulb is the most inefficient bulb which uses only 10% of the electricity (or units consumed) for illumination and the rest is converted into heat. The number of units saved will be equal to the wattage of the bulb multiplied by the time (in hrs) for which it is switched off. But in summers it will also impact air conditioning load as putting lights off will generate less heat.
Energy savings for florescent lights (CFLs and tube lights) by turning them off is a little more complicated to evaluate. These lights are little more expensive than incandescent bulbs but are impacted by frequent switching on and off. The value of energy savings will depend on the rates of electricity in a particular area. In some areas, it may not be efficient to switch it off if one is leaving the room for 5 minutes and in some areas, it can be up to 15 minutes (depending on the rate of electricity). There is also a popular belief that fluorescent lights consume a lot of energy to start up, but actually, the start-up energy is much less compared to keeping the lights on for many seconds.
LEDs are the most effective lights and their life is not impacted by the frequency of switching on and off. So the energy savings by turning them off directly equals the wattage multiplied by the time (in hrs) for which it is switched off. It also does not emit any heat and thus does not impact the cooling of the air conditioners.
Motion Sensor Control of lights: In order to avoid switch ON of lights in corridor, verandah, open area etc. throughout the night, lights equipped with motion sensors are available which senses the motion and switch on the light and automatically after a time delay when the motion stops.
You may find few of the fixtures with motion sensor control as given in amazon are as under:
About the Author:
Abhishek Jain is an Alumnus of IIT Bombay with almost 10 years of experience in corporate before starting Bijli Bachao in 2012. His passion for solving problems moved him towards Energy Sector and he is keen to learn about customer behavior towards Energy and find ways to influence the same towards Sustainability. More from this author.