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Thrifty Thursday - Upgrade to LED Bulbs

Here’s a hack with a high percentage return.  If you pay your own electricity bill, chances are your use is metered and charged by the Kilowatt hour (kWh).  A Watt (W) is measure of power, or energy per second, so a Kilowatt hour is just using 1,000 Watts of power for one hour.

For example, a common household incandescent light bulb uses 60W of power.  If you left this light bulb on for 3 hours a day for a year, it would use 65.7 Kilowatt hours: $$Total\ Energy = Power * Time$$ $$Total\ Energy = 60 W * {3\ h \over day} * {365\ days \over year}$$ $$Total\ Energy = {65,700\ Wh \over year} = {65.7 kWh \over year}$$ Since Thomas Edison invented the incandescent bulb in 1879, however, there have been some improvements to the technology.  The latest is the LEDLight Emitting Diode bulb.  An LED bulb can create the same amount of lightTypically measured in lumens. as an old incandescent light bulb using much less power.  For example, an LED replacement for a 60W incandescent bulb would typically use only 9W.  This creates a savings of 51W per bulb.

To find out exactly how much of a monetary savings this is, you first need to know how much you are paying for your electricity.  You will need to check your bill or electric company’s website, as this typically varies by area, with some of the South and Midwest having the lowest rates, higher on the coasts, and Hawaii topping the charts.  My electric company also charges me more in the summer, when everyone is using their air conditioners, and less in the winter.

For example, let’s look at an average rate of $0.10 per kWh.  Again, let’s assume a bulb we use for 3 hours a day.  Therefore, reducing the power of that bulb from 60W to 9W leads to a savings of: $$Annual\ Savings = (Old\ Watts\ – New\ Watts) * {hours \over year} * {1\ kW \over 1,000\ W} * Energy\ cost$$ $$Annual\ Savings = (60W\ –\ 9W) * {3\ h \over day} * {365\ days \over year} * {1\ kW \over 1,000\ W} * {$0.10 \over kWh}$$ $$Annual\ Savings = {$5.10 \over year}$$ In this example, if the new bulb costs less than $5.10, we’d make the money back in less than a year.  If your energy rate is higher, the payback will be quicker.  Bulbs in locations that are used more often are more obvious candidates for replacement.

These days, prices on LED bulbs have come down so much you can get them for under $2 per bulb, meaning the bulb in the example would pay for itself multiple times over in one year and continue to pay “dividends” for the next decade.  Where else can you get that kind of investment return?

LED bulbs use less energy and last longer than both incandescent and Compact Fluorescent (CFL) bulbs. Prices have dropped enough so the payback time is under a year for many applications.


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