There are a lot of options when it comes to how you heat your water at home. But not all of them use energy efficiently, and some methods contribute to a substantial amount of greenhouse gas emissions. In this episode, we break down the differences between water heaters and why you might want to consider a heat pump water heater.

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 a listener:

Tom Chun: I’m Tom Chun, I live in Barrington, Rhode Island, and I’m an emergency physician.

Megan Hall: Recently, Tom’s water heater stopped working...

Tom Chun: And, it’s winter. I felt like I had to make a quick decision.

Megan Hall: Tom didn’t have time to spare, so he just went with the water heater his plumber recommended. But now, he’s wondering if he should have bought something else. Are there more efficient water heaters out there that are worth the price?

Megan Hall: We had Max Kozlov and Fatima Husain from our Possibly Team look into this question. Welcome, Max and Fatima! 

Max Kozlov: Hi, Megan! 

Fatima Husain: Hello! 

Megan Hall: So, before we start talking about Tom’s water heater options, how worried should he be about the amount of energy these appliances use?  

Max Kozlov: Water heaters are actually pretty big energy hogs. In the average US home, they’re second only to home heating when it comes to household energy use. 

Fatima Husain: Right -- more than refrigerators, air conditioners, and lights! 

Megan Hall: I didn’t realize water heaters used so much energy. How exactly do they work? 

Max Kozlov: Pretty simply. Most conventional ones heat water by burning fossil fuels — either oil or natural gas — and store that hot water in a tank until you need it. Some use electricity to do the heating.

Fatima Husain: But it takes a lot of energy to keep that water warm all day, every day, especially if that tank isn’t well insulated. And all that energy use means higher greenhouse gas emissions.

Megan Hall: How much?

Max Kozlov: Again, it depends on the water heater and the source of your energy, but the average 50-gallon electric water heater releases nearly forty-five hundred pounds of carbon dioxide each year.

Megan Hall: Is that a lot? 

Fatima Husain: Well, the average car releases around 10,000 pounds of carbon dioxide each year.

Megan Hall: So, the average electric hot water heater makes almost half the emissions of a car?

Max Kozlov: Yep. 

Megan Hall: Does Tom have any other options?

Fatima Husain: Yes! Some of the most popular alternatives are tankless and heat pump water heaters.

Megan Hall: What are those? 

Max Kozlov: As the name suggests, tankless water heaters don’t use energy to keep sitting water warm. Instead, the heater warms that water in real time and only when you need it.  

Megan Hall: Does that save a lot of energy?

Fatima Husain: Well, these heaters are slightly more efficient, but they’re not perfect — quickly heating water requires a lot of energy. So, at the end of the day, they only use about 10% less energy than a conventional heater.  

Megan Hall: Okay, so that’s not great either. What’s Tom’s other option?  

Max Kozlov: He could get what’s called a heat pump water heater. You can think of these appliances as like reverse refrigerators. Instead of creating the heat, they use electricity to capture it from the air.

Megan Hall: How much do they cost?

Max Kozlov: They’re roughly 1,000 dollars more than the cheapest traditional heaters.

Fatima Husain: But they’re much more energy-efficient. According to the US Department of Energy, it would only take you about 3 years to pay back that amount with your electricity savings.

Max Kozlov: Heat pump water heaters also release less than half the emissions of your average conventional water heater.

Fatima Husain: And, once more people are able to get their electricity from renewable sources, those emissions will go down over time! Which can’t happen with any appliance that runs off of gas.

Megan Hall: Ok, but what about people like Tom, who has a conventional water heater? Is there anything he can do to be more efficient?

Fatima Husain: Tom could just try to use less hot water in general. That could mean taking shorter showers, using the dishwasher instead of hand washing, or washing clothes with cold water.

Max Kozlov: But the next time he’s in the market for an energy-efficient water heater, his best bet is going with one that runs on a heat pump.

Megan Hall: Great! Thanks, Max 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. Or subscribe to us wherever you get your podcasts. 

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