How Do You Calculate Efficacy Of Lumens?
Light bulbs are given an efficacy rating for how much light they give off that can be seen by the human eye (luminous efficacy) per watt (or radiant flux) of energy they use. This is called LPW or lumens per watt. The higher a light bulb’s efficacy rating, the less it will cost you to use it. Some bulbs, like fluorescent bulbs, have a higher efficacy rating. To calculate the efficacy rating of a light bulb, you need only to do some simple division. Remember, the higher the rating the lower the amount you’ll owe on your electricity bill. Discover the wattage of the bulb either by looking on the box or at the actual bulb. Discover the number of lumens the bulb produces by looking on the box. This may be written as lumen output. Divide the lumens from Step 2 by the wattage from Step 1. This is the LPW.
