Don’t Be a Grinch When It Comes to Holiday Lights
Unless you keep them up until March, it probably doesn’t make sense to replace your holiday lights with LEDs.
We bought them more than a decade ago. Several sets of Christmas lights. Every year we decorate the tree listening to Willie Nelson’s Pretty Paper, the greatest Christmas album of all time. We have two boxes, adding up to a whopping 800-count of little white incandescent bulbs. They put out a beautiful warm yellow light and have survived 10+ seasons of use and storage.
But they must use a horrendous amount of electricity, right? Are these lights ancient history, like the bulb in Catherine Wolfram’s basement? Should I be a Grinch and put these out to pasture? Is it time to replace these lights with LEDs?
I still have the original boxes, but they don’t say anything about electricity consumption. No problem. This is why everyone needs a “Kill-A-Watt” at home. I plugged the first set of lights into the Kill-A-Watt and, bam!, 51.5 watts.
This is for 200 lights so the full set of 800 lights (36 feet) draws 206 watts. This is a lot of electricity. But we only have these lights plugged in about 50 hours per year. Just a couple of hours each evening for about three weeks. By January we are usually pretty sick of Willie Nelson (sorry Willie!) and we pack everything up and put it away.
So 200 watts multiplied by 50 hours yields 10 kilowatt hours annually. We are on Pacific Gas & Electric’s “Time-of-Use” rate and most months in the third-tier so we face a price of about $.30 per kilowatt hour. Thus our annual expenditure for Christmas lights is $3.00. Wait. Only $3.00? Yep. The lights are electricity-intensive, but on for so few total hours each year that it probably wouldn’t make sense to replace them with LEDs.
But what about externalities? How much carbon dioxide are we emitting? PG&E customers emit 0.391 pounds of carbon dioxide per kilowatt hour, so my 10 kilowatt hours lead to about 4 pounds of carbon dioxide emissions. Valued at $36 per ton, this is only about 7 cents per year. Even if you assume a social cost of carbon of $200 per ton, the damages are only 39 cents per year. In fact, the $.30 per kilowatt price is already higher than social marginal cost unless you think the social cost of carbon is stratospherically high. And keep in mind that those new LED lights would require resources too, for manufacturing, packaging, and shipping.
Economics tells us that we live in a world of finite resources, so investments must be made where they yield the greatest return. With energy this means the big ticket items: car, furnace, home insulation, perhaps refrigerator — but not holiday lights that are used only a few hours each year. Unless your house looks like these homes below or you leave your lights on until St. Patrick’s Day, then it probably does not make sense replacing your lights with LEDs either to save yourself money or to save the planet.
So go forth and enjoy your holiday lights! Crank up the Frosty the Snowman and enjoy this holiday season with your family and friends. We will be back next year recharged and ready to engage once again on the world’s most pressing energy challenges. Happy holidays from the Energy Institute!
The blog will be on vacation next week but will return on January 4.
Suggested citation: Davis, Lucas. “Don’t Be a Grinch When It Comes to Holiday Lights” Energy Institute Blog, UC Berkeley, December 21, 2015,
Lucas Davis View All
Lucas Davis is the Jeffrey A. Jacobs Distinguished Professor in Business and Technology at the Haas School of Business at the University of California, Berkeley. He is a Faculty Affiliate at the Energy Institute at Haas, a coeditor at the American Economic Journal: Economic Policy, and a Research Associate at the National Bureau of Economic Research. He received a BA from Amherst College and a PhD in Economics from the University of Wisconsin. His research focuses on energy and environmental markets, and in particular, on electricity and natural gas regulation, pricing in competitive and non-competitive markets, and the economic and business impacts of environmental policy.
Thanks for embedded link (391 pounds of CO2 for a MWh of electrical generation (2015 est.) to PG&E’s post!!!!:
“Greenhouse Gas Emission Factors….”
PG&E’s emission factor is going to drop to 290 lbs CO2/MWh by 2020. A 25% drop in 5 years is rather amazing.
I started converting pounds to grams back in 70’s (which makes it much easier to use our analytical balance to weigh out small quantities of reagents for our home winemaking efforts). I stuck the PG&E data you linked to into an excel spreadsheet to see how many grams of CO2 would be released from using our 1000 Watt ceramic heater for 10 hours (to heat up my office yesterday). I used 10 kWh to heat my office yesterday which released 1.775 grams of CO2 (assumes no line losses per PG&E’s paper).
Math: 391 pounds of CO2/1,000,000 kWh *454 grams/pound=177,514 grams per1,000,000 kWh * (10 kWh/1,000,000 kWh)=1.775 grams of CO2 per 10 kWh of PG&E generated power
It is my understanding that PG&E has been allocating cap and trade CO2 fees to their customers for a few years so your usage already includes some allocations for CO2.
Thanks for posting all the great links!
Lights on inside the house will add heat to the house. The incandescent bulbs’ great inefficiency is in the heat generated. In the Northern Hemisphere, this holiday of lights comes when the weather is cold, and heat is often needed in a house. So the $3 in your estimate is missing the positive externality of reducing the energy demands of the other heating system you use to heat your home. Plus, my experience suggests we have preserved/extended the useful of lights by using them indoors, too. Good solstice post!
These are small nuts — it would be instructive to compute how much carbon was ’emitted’ in the preparation for and travel to the Paris COP21. And there really is no credible way to compute the methane produce by everyone there.
It is not so much how much electricity the lights consume [now that the ‘cost’ of production has been fully amortized], it is the ‘junk’ we will all buy [mostly made in China].
50 hours a year? From 5pm to midnight for 20 days is 140 hours, and my wife compalins that I wait until December to put up the lights. Don’t think it alters the conclusions. Also replacing usable incandescent lights with LEDs wastes energy through manufacturing new items and disgarding usable items, assuming no secondary market.