In search of middle-hanging fruit

When I see an article offering advice on how to save energy or shrink your carbon footprint, I usually click on it, but without much hope or enthusiasm. I can be pretty sure that most or all of the advice in it will be about things we already do, such as:

• Replacing single-use water bottles, napkins, grocery bags, etc., with reusable ones 
• Eating less meat and dairy 
• Composting 
• Walking or biking for short trips, instead of driving
• Washing laundry in cold water and drying it outdoors
• Taking shorter showers and/or using a low-flow showerhead
• Setting the thermostat lower in winter and higher in summer
• Insulating your home and sealing up leaks
• Switching your electricity supplier to one that uses clean energy (or, better yet, community solar)
• Upgrading your old, inefficient light bulbs (honestly, is there anyone who hasn't done this yet)? 

Occasionally, these articles also recommend some bigger changes we haven't made yet, like getting solar panels, driving an EV, or swapping out your furnace for a heat pump. But in every case, we've already considered these ideas and concluded that they just don't work for us at this time. We can't get solar panels because our home electric usage is too small to meet the minimum size requirements for a solar array. We don't want to replace our only car with an EV until we feel confident that it will be practical for long trips. And we aren't prepared to spend $24,000 on a heat pump that would probably increase, not decrease, our winter heating bill.

At first glance, our problem appears straightforward: when it comes to living a greener lifestyle, we've already harvested all the low-hanging fruit. If it's cheap and easy to do, we've already done it. Our house and our car are about as efficient at this point as anything running on fossil fuels can possibly be. To improve any further, we need to reach for the higher-hanging fruit that involves more hassle and/or expense. And that's only to be expected.

But in fact, it's more complicated than that. It's not just that we've already done all the easy stuff; by doing so, we've actually reduced the value of doing the harder stuff.

Take the heat pump, for example. According to the EPA, the 295 therms of gas we burned for home heating last winter produced about 1.56 metric tons of CO2. An electric heat pump would cost us about $24,000 and would last around 15 years, for a cost of $1,600 per year, plus another $100 or so in increased heating bills. That works out to over $1,089 per metric ton of greenhouse gas saved—far higher than the $190 a ton that the EPA under the Biden administration estimated as the "social cost" of carbon emissions. And the reason that cost per ton is so high is precisely because our current carbon footprint for heating is so low. If we hadn't already turned down the thermostat, insulated the attic, and bought a reasonably efficient gas boiler, we'd be doing the climate a lot more good by going electric. As it is, the benefit is pretty slim.

It's the same thing with the solar panels. Unlike a heat pump, a solar array probably would save us money in the long term—but because our electric usage is so small, we can't install one. And while there's nothing to stop us from buying an electric car, the maximum we could possibly shave from our carbon footprint by doing so is 0.21 tons, the carbon cost of the 219 gallons of gas we burned last year. (This year, with Brian fully retired, it will probably be even less.) The problem isn't simply that we've harvested all the low-hanging fruit, and what remains is harder to reach; it's that the higher-up fruit isn't worth as much to us because we've already filled up on the easy stuff.

So where does this leave us? Do we simply rest on our laurels with the fruit we've collected, or do we keep struggling ever higher up the tree in search of ever fewer and smaller apples? 

What I'm hoping is that I can manage to find a middle ground—a few fruits hidden amongst the foliage in the middle branches of the tree. For example, consider the induction burner we bought in 2024. It has taken over about half our cooking, shaving about 2 therms of natural gas use from our monthly bill and about an eighth of a ton from our carbon footprint. Assuming it lasts us ten years, that works out to 1.3 metric tons of greenhouse gas for just $89, or $68 per ton. (The burner also adds about $2.40 a month to our electric bill, but that's almost exactly equal to what we're saving on gas.) A full-size induction stove with an electric oven would cut our gas use by about twice as much—2.6 tons over 10 years—but at a cost of around $1,300 (and possibly several thou more to upgrade our electric panel to accommodate it). That works out to $500 a ton, which is a lot more bucks for the carbon-reduction bang.

So my goal at this point is to take the same kind of half measures with our other fossil-fuel-using devices—starting with our gas boiler. Last summer, after learning that we'd need to spend at least $20,000 (after rebates) on a heat pump that would completely replace the boiler, I speculated that maybe we could partially replace it by installing a through-the-wall heat pump in place of our old, inefficient wall AC unit. I've since dug into this a bit more and found a $1,200 unit that appears to be the same size as our current AC unit, which would allow us to swap it in with no need to cut a new hole in the wall. We'll have to pull the old AC unit out and measure the space to make sure, but if I'm right, we could probably install it ourselves, making that $1,200 (or say $1,300 with tax) the only cost. 

According to the description of the unit, it's sized for a space between 400 and 550 square feet, which is about one-third of the conditioned space in our home. So, at a rough guess, it might be able to cut our gas use for heating by around one-third. If it lasts 13 years, that would be $100 per year for about a half-ton reduction in our carbon footprint, or about $200 per ton. That's less than one-fifth the cost per ton for a full-sized heat pump. It's still a lot more expensive than a few LED light bulbs or a low-flow showerhead (especially since we got most of those for free), but it offers much bigger energy savings, too. It's a medium-sized cost to gain a medium-sized benefit—the perfect middle-hanging fruit.