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Buy Lumens, Not Watts

We typically buy things based on how much of it we get, right? When buying milk, we buy it by volume (litres). So, why should light be any different? For decades, we have been buying lights based on how much energy/power they consume (watts) -- no matter how much light they give us (lumens). Lumens measure how much light you are getting from a bulb. More lumens means it's a brighter light; fewer lumens means it's a dimmer light.

Lumens let you buy the amount of light you want. So when buying your new bulbs, think lumens, not watts.

For example, a 40W (power the bulb consumes) incandescent bulb gives a lumen (light it gives us) of 500. Where as a CFL 9W bulb will give the same 500 lumen output and so will a LED 6W bulb.

Therefore, to get the same light output of 500 lumens, you can either use a 40W incandescent bulb, a 9W CFL bulb or a 6W LED bulb. Additionally, while a 9W CFL bulb from Philips may produce 500 lumen, a CFL bulb from another manufacturer may require higher wattage (aka power consumption) to produce the same lumen. 

 

Bulb Technology  Power Consumption (Watts) Light Output (Lumens)
Incandescent 40 500
CFL 9 500
LED 6 500

 

An LED bulb consumes on average at least 50 per cent less energy than CFLs and around 80 per cent less than mercury. A simple multiplication using the above table with the number of households in India (i.e. 19.27 crore) shows that the country can save up to 675 MW. Simply put, this power saved is enough to meet the peak demand of five Chandigarhs or one-sixth of Delhi.

How much money do I save?

While getting better quality of light, an individual will benefit by substantially lower electricity bills. Incidentally, mercury has also been recognised as environmental hazards, given the poisonous effects of mercury.

  60W Traditional Incandescent 43W Energy-Saving Incandescent (Halogen) 15W CFL 12W LED
Energy Saved (%) - ~25% ~75% ~75-80%
Annual Energy Cost* Rs. 312 Rs. 227.50 Rs. 78 Rs. 65
Bulb Life 1,000 hours 1,000 to 3,000 hours 10,000 hours 25,000 hours

*Based on 2 hrs/day of usage, an electricity rate of Rs. 7.15 per kilowatt-hour, shown in Indian Rupees.