Lighting 101: Math – Can’t Argue With Numbers
It’s time for a lighting upgrade, but you can’t decide if the initial cost of LEDs is worth it, or if they are everything they are claiming to be. LEDs have the reputation of saving energy and money, and the numbers sure don’t lie. The two math problems below will show you the savings you could have by replacing your old, outdated lighting with LED technology.
Math Problem #1
LEDs operate at about 80 percent efficiency, meaning 80 percent of energy is distributed as light and 20 percent is lost as other forms of energy, such as heat. Incandescent light sources, for example, operate at about 20 percent efficiency. Using this knowledge, let’s assume you have an electric bill of $100 and you are currently using incandescent lighting in your home. $80 of your bill is used to heat the room, not to light it. Now say you switch to LED – your previous bill of $100 turns to $20 (wasted energy) and you save $80 (amount of light dispersed).
LED lighting generates the same amount of light at less than 50 percent of the operating energy costs as traditional fluorescent tube school lights. Current fluorescent lights also run on an average of 32-40 watts, while LED replacements for those tubes run on an average of 12-18 watts.
Math Problem #2
Based on the above information, if the cost per kWh (kilowatt-hour) is roughly 12.67 cents (average for 2015), and the difference in fluorescent and LED annual kWh is 236.52, the facility would be saving roughly $29 with just one bulb.
12.76 cents X 236.52 kWh saved = $29 per tube
Now if we look at a facility with 100 fixtures with 2 tubes per fixture (using the same numbers as above):
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