MILWAUKEE — Rather than warmth and good cheer, the twinkle and glow of homes festooned with holiday lights reminds Adam Siegel of carbon emissions and global warming.

Siegel insists he is not a Grinch, only green.

“You can have a beautiful display, a gorgeous display, you can even have massive display, but why do it in a wasteful way?” said Siegel, a blogger from McLean, Va.

There are signs that after several years of floundering holiday sales for energy efficient LED lighting, more people feel the same way.

Manufacturers and retailers across the country report sales that are surprisingly brisk even during an economic downturn. For example, light-bulb maker OSRAM Sylvania said it doubled its LED sales since last year to between 15 million and 20 million LED units.

LEDs, or light-emitting diodes, can be three times more expensive than traditional incandescent lights but they use 90 percent less energy, produce less heat and last longer.

Siegel has done the math on his blog, GetEnergySmartNow.com, which is not affiliated with any energy or lighting company. He calculates that an average string of LED lights saves enough energy to pay for itself in as little as a year.

Calculations by other independent researchers suggest the break-even point could be two to three years, depending on how long the lights are left on.

Regardless of who is doing the math, the upfront cost of LED lighting is almost always worth the investment, especially with more utilities throwing in additional incentives that can range from $2 to $4 per set.

Among the first to switch over to LED lights were large corporations or municipalities that stand to save the most.

At the Milwaukee headquarters of beer brewer MillerCoors LLC, a 200,000-light LED display using 15 miles of lights has been synchronized to music. Company spokesman Mike Jones said LED lights cut holiday lighting costs by 60 percent.

“This is a tough year but we don’t intend to cancel the holidays,” Jones said. “This is a gift to our employees, a gift to the community, and even better, we’re using half the energy.”

The government swapped out traditional lighting on the National Christmas Tree in Washington, D.C., which now has 37,000 LED lights. New York’s Rockefeller Center tree was decorated with 30,000 LED lights on five miles of wire.

LEDs are tiny semiconductors similar to computer chips, and are commonly used in traffic signals, track lighting and electronic devices. LED lights are more efficient because most of the energy in the circuit gets converted to light, whereas up to 90 percent of the energy emitted by incandescent bulbs is wasted as heat.

They’re sturdier, last up to 10 times longer than incandescents and, because they are not as hot, are less of a fire hazard.

Prices for the greener bulbs can still be a barrier for some. For example, Amazon.com sells a string of 100 multicolor LED holiday lights for about $28, while the incandescent equivalent is about $10.

Even so, 21 of Amazon’s top 25 holiday-light sales are LED products.

Christmas Lights Etc., based in Alpharetta, Ga., sold 25 million holiday lights this year, with LED sales up more than 50 percent over last year. Spokesman Aaron Hassen said many LED products sold out quickly.

“It did catch us off guard a little bit, but we’re all learning from the trend,” he said. “I think people are finally understanding what a difference these make.”

Sylvania spokeswoman Stephanie J. Anderson said LED sales will only grow as the technology improves. Companies may even employ solar technology, so that the lights would need no grounded power source.

Not everyone sees the need to deck the halls with an expensive alternative. Brian K. Nagatani, an employment attorney in the San Francisco Bay Area, said there’s no point taking a long-term view.

“I would just buy the cheapest one on the shelf,” said Nagatani, 33. “I mean, you only take it out once a year for, like, three weeks.”

Still, cities like Palm Desert, Calif., that must balance energy use year-round are pushing residents to make the switch.

The city last year offered a free string of LED lights to residents in exchange for traditional lights. Between 2007 and this year, the number of swaps has tripled from 568 units to 1,748 and counting.

“In the desert you can imagine energy use is high, like with air conditioning in August,” said Patrick Conlon, who directs the city’s Office of Energy Management. “We did this to stir up enthusiasm for energy efficiency, and we’re pleasantly surprised how well it’s worked.”

The program cost about $26,000 this year, he said, and the city might have to consider rebates next year instead of free replacements if interest remains so high.