Are My Christmas Lights Costing Me a Fortune?


Holiday lights decorating the house.


Are my Christmas lights big energy wasters? How much do they impact my energy bill each year? I was curious to find out, so I went to Kmart, wrote down the figures listed on the boxes, and then plugged them into my computer. It turns out that the old style Christmas lights cost the most money to run by far. On the other hand, the newest bulbs add a lot of festive sparkle for very little cost.


Three Types of Christmas Lights


I don’t know about you, but I’m old enough to recall the 1970’s and the strings of big screw-in, colored bulbs that graced every home in the neighborhood. They were about 3 inches long, bright, and comforting in a way—I could even feel heat from them if I held my hand close. Some people still use those old lights, but each bulb is 7 watts. If I were to use six strings of lights with 25 bulbs on each string, I would end up burning more energy than ten 100 watt light bulbs. Quite a bit of juice!



In the 1970’s, the newer strings of “mini-bulbs” began to appear—the tiny colored lights. They were smaller and dimmer, so more were packed onto a string—typically 100 bulbs on a 25 foot string. Like the old bulbs, these were incandescent—they gave off light from a heated filament inside. But they were so small they used much less energy  than the old bulbs, under half a watt each.


Christmas lights.This was all well and good, until the first bulb burned out. The whole string went dark and I couldn’t tell which one was bad.  I had to change each light out one by one until I found the culprit.   It took a few years, but the wiring was finally redesigned to eliminate this annoyance.  That’s when I really came to love these colorful little bulbs.


At about the same time, the LED was invented—that is, the “light emitting diode”. LED’s are solid state lights that are made in much the same way as computer chips. There is no heated wire in them, so they waste little energy and have a very long life span, typically 20,000 hours or more. Until recent years, the problem with LED’s has been their high cost. Now they are so cheap they can be used for most kinds of lighting. In fact, on my trip to the store I discovered that LED light strings are more common than the others, and often nearly as cheap to buy. Christmas is going semiconductor.


Calculating the Cost of Each Type


Based on the figures I gathered, it was not hard to calculate the energy cost of each type of bulb—for the whole house and for the season. To do this, I made several assumptions. For example, I assumed the lights would be plugged in an average of ten hours each day and for one month each year—from after Thanksgiving to about New Year’s.


Why ten hours per day? I considered two scenarios. Sometimes I plug in the lights in the late afternoon and leave them on until the following morning—perhaps 15 hours. Other times I plug them in after work and unplug them before bed—maybe as little as 5 hours per night. If I do these two things about equally during the season, I will average about 10 hours per day.


The final cost for each type of light is shown in the table below. If the time you burn your lights is different than 10 hours a day, it is easy to adjust those results in proportion. For example, if you burn your lights for 5 hours a day instead of 10, the final energy cost will be half what is shown in the table. In case you would like to experiment with all of the factors yourself, here is a formula showing how I got these answers:


Christmas light cost calculation.
The table below shows the energy cost for all three kinds of bulbs, using strings about 25 feet long. I assumed a typical house would require six strings, and also that the cost of electricity would run 12¢ per kilowatt hour, a common figure in the U.S. today. Here again, you can adjust the cost in proportion to your own figures.


Holiday light cost.


Are LED The Best?


Though I like those warm, old style bulbs, it turns out they would cost me about $38 per year for energy. For that kind of money, it would be easy to afford switching to a newer style of lights. If I switched to the incandescent “mini-bulbs”, I would spend less than one-fourth as much on energy, only $9 per year.


However, my biggest savings would come by switching to the new LED lights. By doing this, I would spend twenty seven times less on energy each year, or only $1.40. For this kind of savings, I could even afford to go “hog wild” and buy more lights. Then again, I could probably snap up some new lights at half price for next year if I wait for an after-Christmas sale.


This exercise is a great example showing the Power of Zero.  By making a conscious choice to analyze something we seldom think about, I found there are real savings to be had by upgrading to new lights.  In addition, if I take it a step further, I can see an incredible reduction in the power I consume—all the way from 52.5 kwhr down to 1.944 kwhr.  Using a percent change calculator,  this turns out to be a 96.3% reduction in energy use!  My simple lifestyle upgrade therefore saves money, saves power, and is better for the planet. In a case like this, Less is More.



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