Wednesday, December 14, 2016

LED Light Bulbs

When we first moved into this house 10 years ago we started replacing all incandescent light bulbs in the house with more energy efficient fluorescent light bulbs (the curly ones).  It took a couple of years as we waited for each bulb to go out before replacing it.  As the years have past, light bulb technology has changed and fluorescent light bulbs are being phased out by LED bulbs.  LED bulbs look more like incandescent light bulbs in shape, but use less energy than fluorescent light bulbs and last longer.  For typical standard use, the manufacturer states a lifetime of 13.5 years, compared to 7 years for fluorescent light bulbs.

A standard 60 watt incandescent light bulb uses 60 joules of energy each second.  The equivalent fluorescent light bulb uses 13 joules of energy each second.  The equivalent LED light bulb uses 9 joules of energy per second.  Assuming a light bulb is on 3 hours per day (considered standard usage), I computed the following annual energy usages for each style of bulb.

Incandescent = 236,520,000 Joules = 65.7 kwh

Fluorescent = 51,246,000 Joules = 14.2 kwh

LED = 35,478,000 Joules = 9.9 kwh

Assume an electricity cost of $0.10 per kwh of energy use and you find an incandescent light bulb costs $6.57 per year, a fluorescent light bulb costs $1.42 per year and an LED light bulb costs $0.99 per year to operate.  My house has about 75 light bulbs.  It seems high, but walk around your house and count up the number of light bulbs.  You'll probably find just as many, if not more!  For my home, annual costs add up to:

Incandescent = $492.75

Fluorescent = $106.50

LED = $74.25

I don't know about you, but $74.25 is a LOT less than $492.75.  Not too mention the frequency of changing light bulbs is drastically reduced and much less energy is used!  The moral of this story?  Go out and purchase LED light bulbs for your home! 

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