With the basic building block of the light bulb, people like Jerry Fink turn the lengthening nights into something to look forward to.
"Up on the hill there we have the manger scene, three wise men, shepherd, sheep, the donkey," he says, surveying his yard in South St. Paul. "They all light up."
Jerry walks from outlet to outlet, bringing his South St. Paul yard to life. Dozens of fans start blowing, and lumps of canvas lurch upward from the lawn.
"Looks like everything's starting to move," he says, as SpongeBob Squarepants and the Nutcracker rise up side-by-side. "Outside of that, I have 135 plastic figurines. Each one lights up."
Just how many bulbs are involved in the whole project?
"We have about 15,000, I counted up."
Jerry's holiday spirit comes at a price. He figures he's got about $8,000 in decorations. It takes him 100 hours to string all the lights. And for the first time last year, Jerry actually ran the numbers on how much power he was using: $500 extra on the bill between Thanksgiving and New Years.
Now, with 15,000 bulbs and an army of inflatables, Jerry makes the papers. Buses and limos pass by on tours. But for every Jerry Fink, there are thousands of more modest displays drawing extra power from the grid. Like mine.
Here's the math on my own St. Paul display:
Two strings of icicle lights across the front awning with 300 mini-bulbs on each one. Add another two strings inside the front porch and about 300 more on the Christmas tree, also in the porch. That's 1,500 half-watt bulbs for a total of 750 watts.
My timers keep them lit seven hours a day or about 250 hours from Thanksgiving to New Years.
Right now my power company charges $0.072 per kilowatt hour (or $0.000072 per "watt hour". That's 750 watts times 250 hours, multiplied by $0.000072 -- $13.50.
That seems like a small price to pay for Christmas joy.
But what about pollution? My power company makes 83 percent of its electricity from coal and natural gas. This is pretty standard for the U.S. Coal puts out two pounds of carbon dioxide for every kilowatt hour of electricity; gas about one pound. Apply these ratios, and it turns out my modest display of holiday spirit accounts for 252 additional pounds of carbon dioxide Santa and his reindeer get to fly through on the way to my rooftop.
Turns out that's not as much CO2 as I spew from my tailpipe burning one tank of gas, as I tool around town looking for the perfect gift.
But with global warming a generally accepted fact, those extra contributions this time of year do add up. Putting aside the massive commercial and municipal displays, let's say one in 20 U.S. households has a display as large as mine. That's $75 million of electricity and 1.4 billion pounds of carbon dioxide.
To be thorough, there's one more cost worth asking about: Light pollution, which can confuse nocturnal animals and dulls our view of the night sky, which matters a lot to some people.
Josh Nollenberg is a professor at the University of St. Thomas -- and an astronomer, "which means I study levels of light," he says. Josh brings a light-output meter on a visit on to St. Paul's Rice Park, where we approach a giant tree said to have 50,000 lights on it.
The reading: 20.6 microwatts.
Putting that in context, Josh says, "that's not a lot of power. But remember that's just the power from the photons that are coming from the tree itself."
In addition to this tree with 50,000 bulbs, trees all around the park are strung with thousands and thousands of white bulbs, in a spot that is otherwise pretty dim this time of night. Should we care about that at all?
"There is a lot of light pollution already, and it's what gives you the diffuse orange glow that you see over cities," Josh says. "Holiday lights do add to that. But, on the other hand, certain types of lights are better than others."
Our astronomer is a fan of LED Christmas lights, which are getting a big commercial push this year. While the standard incandescents throw their light off in all directions, LEDs are directional. That means if they're set up in a mindful way, much less light escapes up into the sky, where no one can enjoy it anyway.
LED lights are also a revolution on the electricity front. Each bulb gives more light with just a fraction of the power used by an incandescent.
Homeowner Jerry Fink is starting to make the switch and hoping it'll make a big dent in his $500 power charge.
But LED strings are pricey -- more than $1 per foot. It'll be some time before they replace the bargain lights most people still use. So what is an environmentally-conscious holiday light addict to do? I called up a particularly conspicuous homeowner: Alek Komarnitsky in Boulder, Colorado, with 15,000 Christmas lights and several inflatables.
"We've got three Webcams so that people on the Internet can not only view those Christmas lights and decorations, but they can actually control them," Alek says. "They can turn them on and off with the click of a mouse."
Alek soothes his conscience by paying extra to his power company to support wind energy. And each holiday season, he calculates his carbon emissions and makes a compensating donation toward alternative energy research.
"I don't want to raise the flag and say, 'blah blah blah, I'm such a great guy, I'm Al Gore's buddy' or whatever. But it just seemed like the right thing to do," he says. Alek has also used his Web site to raise more than $15,000 for research into an autoimmune disease that affects his two sons.
Apparently, his lights put people in a giving mood.
In the end, there is no easy way to complete the math equation on holiday lights. We can measure the costs in dollars, carbon, or adding to the dull orange glow that surrounds our cities and towns. But until someone figures out a scientific measurement for holiday cheer and the goodwill it inspires, the benefits will be much more difficult to pin down.