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A big source of carbon pollution is lurking in basements and attics » Yale Climate Connections

Dear readers,

Like many of you, I’m working to make my life more climate-friendly. So this month, I’m offering the first in an occasional series in which I’ll share the research findings and lessons that I’m applying at home. Got questions? Send them to [email protected].

— Sara

When the air conditioning at my home died in mid-summer, the time of year when the conditions outdoors in central North Carolina are at their most torrid, my first reaction was dismay. But with every crisis comes opportunity: in this case, a once-in-a-decade chance to slash my household’s carbon pollution.

When I purchased my home not long ago, it included several machines that run on natural gas: a water heater, a furnace in the attic, and a gas package or “gas pack” unit that consumed natural gas in the winter to warm the house and electricity to cool it in summer. The last machine is the one that broke.

In its reliance on natural gas, my house is not atypical. Half of U.S. homes burn natural gas for space and water heating. But though the word “natural” can give natural gas a pleasant connotation, it is in fact a fossil fuel composed primarily of methane, a potent planet-warming gas. Found deep beneath Earth’s surface, natural gas is often obtained by the controversial practice known as fracking and transported to American homes via a vast, leaky, occasionally explosive network of pipelines. And burning natural gas produces carbon dioxide that will warm the atmosphere for the next 300 to 1,000 years.

Natural gas has been portrayed as a “bridge” fuel because its combustion creates less carbon dioxide than that of coal or oil. Still, burning it at my home produced about 5,000 pounds of carbon dioxide in a 12-month period, or roughly 40% of the total carbon pollution from my household that year, according to the EPA’s carbon footprint calculator. That fraction would be smaller in a non-pandemic year — more driving, less working from home — but even so, it would remain a substantial portion of my household’s contribution to heating the planet.

The secret to cutting your carbon footprint: Make a few decisions well

To take action on climate change, we’re often urged to make small changes: recycle, replace our light bulbs, carry reusable grocery bags, and so on. I’ve written about my ambivalence toward such messages, which can obscure the role that governments and large companies play in the climate crisis.

I also find those admonitions frustrating because they’re a form of misdirection. They draw your attention toward a large number of behaviors you’re asked to perform frequently — switching off the lights when you leave a room, remembering to set the washing machine on cold water, taking shorter showers — and away from a small number of choices, made rarely, that are actually responsible for the bulk of your household carbon pollution.

“You just need to make four or five big decisions well,” explains Saul Griffth in “Rewiring America: A Field Manual for the Climate Fight,” a 2020 handbook available as a free download. “Make them well and you can pretty much forget about the day-to-day hand-wringing. These infrequent decisions are the ones that lock us into using either a lot of energy, or a little, and into spewing carbon dioxide, or not. If we design our personal infrastructure right, we will be able to live our lives without sweating all the small things.”

One of those big decisions, if you’re a homeowner, is replacing your broken-down gas- or oil-burning furnace or HVAC system with an electric one. (Another biggie, if you can afford it, is making your next car an electric vehicle.) 

Think about it: The lifespan of a gas pack unit is roughly 10 years. If I had decided to replace the old machine with a new one just like it, I would have committed my household to burning natural gas from now until approximately 2031, producing tens of thousands of pounds of carbon pollution in the process.

And the coming decade is a crucial one for cutting back on that pollution. As the Intergovernmental Panel on Climate Change put it, absent “a sharp decline in greenhouse gas emissions by 2030, global warming will surpass 1.5°C in the following decades, leading to irreversible loss of the most fragile ecosystems, and crisis after crisis for the most vulnerable people and societies.”

The case for heat pumps

So I chose a different option: an air source heat pump, which can heat and cool my home year-round running entirely on electricity. That electricity is provided by my local utility, which produces 60% carbon-dioxide-free electricity. Most of the zero-carbon electricity in that mix comes from nuclear plants, with renewable sources expected to see continued growth this decade.

The anticipated expansion of renewables is a key point: Unlike a gas pack unit, which is guaranteed to burn fossil fuel every day until it dies, the electric heat pump has the capacity to get cleaner each time a wind turbine or solar panel hooks up to the grid. That makes a heat pump a crucial investment in a climate-friendly future. (For more on the advantages of electrification, see this 2017 post from David Roberts.)

Even if your utility’s electricity mix still contains fossil fuels, it’s likely that a heat pump is better for the climate than an old-fashioned gas- or oil-powered heating system. In fact, a 2020 study published in the journal Nature Sustainability found that in most regions of the world, heat pumps are less pollution-intensive than the fossil-fueled alternatives.

The Rocky Mountain Institute published similar results in a 2018 report by that looked at the result of switching to heat pumps in four U.S. cities: Oakland, California; Houston, Texas; Providence, Rhode Island; and Chicago, Illinois: “Electrification already reduces carbon with today’s technology and electric grid in all but the most coal-heavy regions.”

The cost of heat pumps

But there must be a catch, right? You might expect the climate-friendly option to be substantially more expensive than fossil-fuel systems, but a local HVAC company quoted me equivalent prices for new gas pack units and heat pumps. I went with an energy-efficient option and smart thermostat that qualify for utility rebates and a federal tax credit; the net price for the unit plus labor was $7,175.

Because I already have ductwork in my home for a forced-air system, the process was simple. Workers installed the heat pump in a few hours, capped the natural gas line, and hauled away the old unit. They also completed minor electrical work because the heat pump will require more electricity on cold winter days than the old natural gas system did.

What about day-to-day operating costs? I’m expecting to pay less for natural gas but more for electricity during the coming winter. Based on present-day electricity and natural gas prices, my back-of-the-envelope calculations suggest that with the new heat pump, I’ll pay $27 extra per year in heating costs. I’ll monitor my bills during winter 2021-2022 and report back in this space if that estimate turns out to be wildly inaccurate.

Under many scenarios, consumers actually see savings with heat pumps. Building new gas mains is expensive, so in new construction and retrofitted homes without existing gas service, lifetime costs are often lower with all-electric options, according to the Rocky Mountain Institute report.

Individual consumer choices, of course, are no substitute for government and corporate action to cut carbon pollution. Renters don’t get to select their HVAC systems, to name just one barrier to widespread adoption of heat pumps. Financing is another obstacle. “Most Americans don’t have much in savings for an emergency, so they rush out and buy the cheapest air conditioner when theirs breaks,” Griffth said on a May 2021 episode of the Energy Gang podcast.

But if you can make a heat pump work for you, I recommend it. I am absurdly proud of mine.

Got a question about climate change? Send it to [email protected]. Questions may be edited for length and clarity.

Tom Toro is a cartoonist and writer who has published over 200 cartoons in The New Yorker since 2010.

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