In making their holidays merry and, above all, bright, some lighting fanatics have seen their electric bills spike $50 or more.
That's some serious green, although not the kind that this column is about.
For once, though, there is an eco-option born of technology, not sacrifice. It's time to deck the halls with LEDs.
Light-emitting diodes have always held the promise of massive energy savings. But the early versions were dim and expensive, and the colors weren't true.
Lighting experts are still tinkering with the technology to get LEDs that can replace the bulb in an end-table lamp. Meanwhile, they're increasingly common in traffic signals, brake lights and commercial fixtures.
The colored lights on the Cira Centre are LEDs. Ditto for Boathouse Row.
But where they really shine is in holiday lighting displays.
The breakthrough came in 2001, after a Yardley entrepreneur, Dave Allen, and his brother Mark, an engineer in California, figured out how to make LEDs work with a common household electric plug. Previously, they needed transformers.
The Allens' company, Fiber Optic Designs, licenses their technology to Colorado-based Holiday Creations.
Now holiday LEDs use a fraction of the energy needed for incandescents. Last year, the U.S. Department of Energy estimated that incandescent Christmas tree lights kept on 12 hours a day for 40 days would cost $23.95 in electricity. With LEDs: 54 cents.
Plus, LEDs don't get hot, which makes them safer around flammable greenery.
That also means the outside of the light can be made of unbreakable epoxy instead of glass.
And they last up to 30 times longer.
The pros have embraced holiday LEDs.
Last year, the national Christmas tree in Washington, the tree in New York's Rockefeller Center, and the Times Square New Year's ball all went LED.
This year, Philips Lighting is upping the ball's glitter quotient with more than 32,000 LEDs, digitally controlled to create 16 million colors - must be pretty subtle - and "billions" of effects.
GE Consumer and Industrial touts the Washington tree's 45,000 LEDs as "the most energy-efficient holiday display in our national history."
Closer to home, Longwood Gardens, whose annual display attracts 220,000 gawkers, has been gradually converting and now is 80 percent LED.
The King of Prussia mall just converted 300,000 of its half-million holiday lights. Marketing manager Mark Bachus saw some LEDs at a sister mall and loved how they made the decor "pop."
Having no idea they were so energy-efficient, he wondered how he'd get the bean-counters to go for it.
They found the energy savings would pay for the lights in one season.
Don't underestimate the energy impact of home displays. Americans go nuts over them.
In 2003, a Department of Energy report estimated that the little strings of cheer consumed 2.2 billion kilowatt-hours a year - enough to power 200,000 homes.
Last year, Home Depot alone sold 40,000 miles of Christmas lights - enough to circle the planet 1.6 times.
Spokeswoman Jennifer King wouldn't say how many of those were LEDs, but she did note that annual holiday LED sales were increasing by double digits. In one local store I visited, the shelves were split about 50-50 between LEDs and incandescents.
The LEDs are pricier - say, $9.99 for a string of 25 big bulbs, compared with $6.99 for incandescents - but you'll make it up in no time.
So I bought a string and draped them over my computer. One colleague says the light is a tad metallic. Another says the red is orangey, the blue nudging toward violet.
I think they look great.
What's astounding to me isn't that LEDs are selling so well, but that incandescents are selling at all.
And how fitting, with all the discouraging news of ice melting, that curbing energy use could benefit a place on so many little kids' minds this time of year: the North Pole.