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AskPablo: Green Holiday Lights?

| Monday November 26th, 2007 | 4 Comments

LED.jpgNow that turkey day is behind us the holiday season is in full swing. Despite my annual Grinch-like attitude, it once again looks like Christmas threw up inside my house (thanks to my wife — she says its an addiction she’s had since childhood) and there is no shortage of holiday lights. We all have a love/hate relationship with our 100-bulb strings of green wire that always seems to have one burned out bulb, rendering the whole tangled mess out of commission. This year there is an economical solution to the failings of the traditional holiday lights and our concerns over energy use: LED holiday lights. This week I am looking at the benefits of these energy efficient replacements.


A traditional string of 100 clear 2.5v/170mA lights are available from one online retailer for $13.95 although you can easily find lower-quality ones for less. They are made in China and come with a warning about the presence of lead. When a bulb goes out, the whole string might go dead, although newer strings feature an “always on” design that eliminates this problem. The bulbs are made out of glass and are easily broken. Along with their high energy demand (42.5 Watts) and low efficiency (94% heat) they even present a fire hazard, especially when multiple strings are connected to the same outlet.
LED light strings have traditionally been quite expensive but the price has come down significantly. This year Costco is selling two different sets of 100-bulb LED strings for $7.39 and $8.99. The benefit of the LED lights is that they last 200,000 hours, do not contain glass, do not burn out, and use much less electricity (between 2 and 4 Watts). This also means that they put out much less heat and do not pose as much of a fire hazard.
If you traditionally decorate your house with twenty 100-bulb strings you require 850 W. If you turn your lights on for 6 hours per day this adds up to 5.1 kWh per day. If you put your lights up a month before Christmas you will have used 153 kWh to spread joy into the world, not to mention heat and light pollution. At $0.15/kWh the cost for this would be over $22.
With LED lights you would only use 60 Watts, using 0.36 kWh per day, 10.8 kWh for the month, or only $1.62. For even further savings you could put the lights on a timer and only turn them on for 3 hours per day.
This year LED holiday lights are available at WalMart, Target, Ace, Amazon.com, and many other retailers. Since the price is finally right, perhaps it is time for you to trade in those wasteful old lights and start dreaming of a green Christmas…
Pablo Päster
Sustainability Engineer
www.AskPablo.org


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  • Werner

    A photocell timer makes it even more efficient.
    No moving parts and less power use by the timer.
    Great advise Pablo.

  • jankdc

    Let us know how they look. Earlier led xmas lights had a kind of strobe effect.

  • http://www.AskPablo.org Pablo

    Jankdc, AC electricity is supplied at a frequency of 60 Hz in the US. Since incandescent bulbs have a glowing filament which doesn’t cool fast enough between the alternating currents you perceive a constant glow. LEDs, on the other hand, are silicon-based and turn on and off with each oscillation, creating a barely detectable 60 Hz “strobing” effect. While this may be noticeable at close range, it is not detectable on the outside of a house. The light quality is also better so you get nice white lights, rather than a yellowish glow.

  • http://www.AskPablo.org Pablo

    Here is some new information about the lead in holiday lights:
    http://www.cnn.com/2007/HEALTH/12/10/christmas.lights/index.html