This episode originally aired on December, 15, 2020.

Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall. 

Today, we have a question from our very own Fatima Husain.

Fatima Husain: When I was looking to buy holiday lights, I saw incandescent  and LED options — and I wondered, which type should I buy? Is there really a big difference between the two?

We had Isha Chawla from our Possibly team help Fatima figure it out. Welcome, Isha and Fatima!

Isha Chawla: Hi, Megan!

Fatima Husain: Howdy!

Megan Hall: So Fatima, what made you ask this question about holiday lighting?

Fatima Husain: Well, this is the first year I’ve put up lights for the holidays at my own place. But also, my family is Pakistani…

Isha Chawla: …And I’m Indian. So in our corner of the world, we usually string up A LOT of lights this time of year for weddings. 

Megan Hall: Ok, so, there are lots of reasons to buy lights this time of year! What are all of my options? 

Fatima Husain: We don’t have time to talk about every type of light out there, so let’s focus on the most common two for now: incandescent lights and LED lights.

Megan Hall: Ok, tell me about incandescent lights. 

Isha Chawla: Incandescent lights are the type of lights most of us imagine when we think of outdoor or tree lighting. 

Fatima Husain: They work by pumping electricity through a filament, that thin little wire in each bulb. When the filament gets hot, it emits light in all directions. 

Megan Hall: How are incandescent lights when it comes to using energy?

Fatima Husain:  Not great. They’re actually pretty inefficient. Most of the electricity pumped into those bulbs gets wasted. Nearly 90% of their energy is lost as heat

Isha Chawla: And you can imagine that fiery hot bulbs pose a safety risk at home, as well.

Megan Hall: Yeah, putting a hot bulb next to a dry Christmas tree doesn’t sound like the best idea. What about LEDs?

Fatima Husain: LED stands for light-emitting diode. A diode is an electrical device that emits light when you run a current through it. 

Megan Hall: Does that create heat, too?

Isha Chawla: No, LEDs don’t lose any energy to heat, which is why they are so much more efficient than incandescent lights.

Megan Hall: How much more?

Fatima Husain: To find out, I bought some incandescent and LED string lights to compare. I busted out the old pen and paper and calculated how much energy each set of lights will use during the holidays. 

Isha Chawla: You can do this math at home with your own string lights, too, because every set of lights should be labelled with its electrical ratings.

Megan Hall: So, Fatima, what did you find?

Fatima Husain: Per season, my incandescent lights use over 6 times the amount of electricity than my LED ones. 

Isha Chawla: And according to the U.S. Department of Energy, LEDs use about 75% less energy than incandescent bulbs.

Megan Hall: Wow. That’s a big difference! But, LED lights are also more expensive than incandescent lights, and I only use them for a few weeks in December. Is it really worth it to make the switch?

Isha Chawla: Incandescents might be cheaper at the store, but they don’t last as long. 

Fatima Husain: A string of LEDs will work around 25 times longer than incandescent bulbs!

Isha Chawla: And don’t forget your electric bill! It costs about $10 to run incandescent lights on an average sized tree during the holiday season. 

Fatima Husain: Megan, take a guess: How much do you think it would cost if you used LEDs instead?

Megan Hall: Hmmm… I don’t know! How much?

Fatima Husain: 27 cents.

Megan Hall: Really? Just 27 cents? 

Isha Chawla: Yes! And those numbers add up, especially for folks who might leave their lights on ALL the time during the holiday season, making the initial investments in LEDs really worth it!

Megan Hall: Great! Thanks, Isha and Fatima! 

That’s it for today. For more information, or to ask a question about the way you recycle, use energy, or make any other choice that affects the planet, go to the public’s radio dot org slash possibly. 

Possibly is a co-production of the Institute at Brown for Environment and Society and the Public’s Radio. 


Fatima’s Calculations for this Episode

A single incandescent bulb in my string lights draws 0.425 Watts per bulb, while a single LED bulb draws 0.068 W. I multiplied those numbers each by 250, because that’s how many lights I have in each string. 

Then I calculated the kiloWatt-hours of each circuit assuming I keep my lights on for only 4 hours per day, and then multiplied that number by 30 since I usually keep my lights up for a month before taking them down.  

This math comes out to: 


0.425Watts/bulb x 250 bulbs/string x 1kWh/1000W/h x 4 hours/day = 0.425kWh/day

0.425kWh/day x 30 days/season = 12.75 kWh/season


0.068Watts/bulb x 250 bulbs/string x 1kWh/1000W/h x 4 hours/day= 0.068kWh/day

0.068kWh/day x 30 days/season = 2.04 kWh/season

The post What kind of holiday lights should I buy? appeared first on TPR: The Public's Radio.