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Building Matters

Five Ways to Reduce Carbon Emissions in Your Home

Start by understanding the difference between energy use and embodied carbon and "now" and "later" emissions to set your priorities

There is much talk lately about how artificial intelligence will cause a job apocalypse. If you work in the trades, you’ll be glad to know that a recent study from Cornell University says that most construction-related jobs, from concrete finishers to stonemasons, are considered “occupations with no labeled exposed risks.” On the other hand, the study declared that my career as a “news analyst, reporter, and journalist” is 100% at risk. So when I was asked to write an article about how to reduce carbon emissions in homes, I thought I would check out the competition from AI. I asked ChatGPT the question to see how soon I would be out of a job. Here is the list it generated:

  1. Upgrade to energy-efficient appliances. Upgrading to energy-efficient appliances like refrigerators, washing machines, and air conditioners can significantly reduce carbon emissions in a home. These appliances use less energy to operate, reducing the amount of carbon emissions released into the atmosphere.
  2. Install a smart thermostat. A smart thermostat can help regulate the temperature in a home and save energy. It can be programmed to adjust the temperature automatically based on your schedule and can even be controlled remotely using a smartphone app. This can significantly reduce the amount of energy used to heat and cool a home.
  3. Improve insulation. Proper insulation in a home can reduce the amount of energy needed to heat and cool it. This can be achieved by insulating walls, roofs, and floors. Adding weather stripping to doors and windows can also help prevent drafts and reduce the amount of energy used to heat a home.
  4. Switch to energy-efficient light bulbs. Energy-efficient light bulbs like LEDs use significantly less energy than traditional incandescent bulbs. Replacing incandescent bulbs with LEDs can reduce the amount of energy used to light a home by up to 75%.
  5. Use renewable energy. Installing solar panels or wind turbines can help reduce carbon emissions in a home. While the initial cost of installation can be high, over time the savings on energy bills can offset the cost. In some areas there are even incentives and tax credits available for installing renewable energy systems.

Despite Cornell’s findings, I suspect that ChatGPT will not put me out of a job for a while. When it comes to carbon emissions in homes, some of its answers are out of date, and some need clarification.

Energy use and embodied carbon

The fundamental problem with the list generated by ChatGPT is that actions to reduce carbon emissions are not necessarily the same actions that one would take to reduce energy consumption; they are often different things. ChatGPT also seems to have no understanding of embodied, or upfront, carbon, which we can refer to as “now” carbon. Let’s look at its advice in greater detail:

  1. Upgrade to energy-efficient appliances. We are talking carbon, not energy, so the decision to upgrade an existing appliance has to be weighed against the “now” carbon emissions associated with manufacturing and delivering those appliances. If they are powered by fossil fuels on site, using less fuel will lower direct carbon emissions. If they are powered by electricity, which has indirect carbon emissions, then it may not reduce overall carbon emissions by very much because it will take years for the “later” carbon savings—those associated with energy use—to be greater than the “now” carbon costs of making them.
  2. Install a smart thermostat. When there are few “now” carbon emissions from the manufacture of a product to weigh against reduced energy use, energy efficiency can sometimes be seen synonymously with lower carbon emissions. Still, not all “smart” technologies are living up to their promise. A recent study from the National Bureau of Economic Research found that “smart thermostats fail to deliver the expected energy savings; our results show that such technologies have neither a statistically nor economically significant effect on energy use.” We need to look beyond a product’s advertising to make an informed decision.
  3. Improve insulation. Like appliance upgrades, this is an oversimplification at best. First, there is the cost of embodied carbon in the new insulation to consider. Second, insulation upgrades, like all home performance upgrades, need to be prioritized. An energy audit can help to determine where and how to upgrade insulation, which often must be preceded by air sealing. Also, some insulation upgrades are much more disruptive than others, and the more disruptive a project is, the more carbon intense it likely is as well.
  4. Switch to energy-efficient light bulbs. Sure, but hasn’t everyone done that by now? There’s nothing wrong with this advice; it just seems out of date.
  5. Use renewable energy. Finally, ChatGPT  is talking some sense, although home-size wind turbines have been proven ineffective.

A better list for lowering carbon emissions

ChatGPT didn’t do a terrible job answering the question, but as we learn more about climate change and how we can make an impact in our work, priorities have shifted. AI still gets its information from searching the internet, which is full of old news and lacks nuance.

Until we find a big chunk of low-carbon electricity to power the world, we have to continue to reduce demand. While we still can’t lose sight of operating or “later” emissions, we’ve learned more recently that “now” carbon emissions are critically important. This makes each design and building decision more nuanced than ChatGPT’s answers make clear.

Here’s my list of five ways to reduce carbon emissions, starting with the lowest cost and complexity, a sort of updated version of the classic Minnesota Power Pyramid of Conservation from 2008 (shown above). Some will cut energy consumption, which may reduce carbon emissions, directly if you are on gas and indirectly if on electricity. This is biased toward a northern cold climate, but much of it is universal.

  1. Get an energy audit. A blower-door test, thermal imaging, a duct test, and an educated visual inspection will help to determine how a house is wasting energy and how to prioritize upgrades. Otherwise, you are just guessing.
  2. Start with low-hanging fruit. Often the low-cost improvements have the greatest impact on energy upgrades, including changing our habits. Air sealing and weather stripping is affordable work to do and should come before insulation upgrades; you can use a clothesline instead of a dryer; and yes, if you haven’t already, switch to energy-efficient light bulbs.
  3. Mitigate heat loss. According to Harold Orr, after air leaks, uninsulated basements and poorly insulated attics are often the greatest sources of heat loss in our homes. Of course, your energy audit will tell the tale. Once you’ve tackled the low-hanging fruit, you can start insulating attics and basements, and I am a big fan of removable window inserts as a way of reducing heat loss from windows without incurring big upfront carbon impacts.
  4. Get off gas. Electrification is obviously one of the most important steps for reducing carbon emissions, but it costs money and comes with “now” carbon emissions. That’s why it should not be done unless you have tackled numbers 1–3, which will reduce heating and cooling loads, saving money on equipment and saving energy in operation. You want to get the smallest heat pump possible; they leak, and most refrigerants are serious greenhouse gases.
  5.  Sell the car. Seriously. Building emissions and transportation emissions are two sides of the same coin. As Alex Steffen has written, “There is a direct relationship between the kinds of places we live, the transportation choices we have, and how much we drive.” As transportation expert Jarrett Walker notes, “Land use and transportation are the same thing described in different languages.” In the United States, transportation is the single biggest source of greenhouse gas emissions. So find a house in a walkable neighborhood, get an e-bike, or if you absolutely need a car, get a smaller electric one. Where you live and how you get around have the biggest influence on your carbon emissions. As the British group Built Environment Declares noted, it’s one big picture. “If we are to reduce and eventually reverse the environmental damage we are causing, we will need to re-imagine our buildings, cities and infrastructures as indivisible components of a larger, constantly regenerating and self-sustaining system.”

We’re all just beginning to learn about AIs like ChatGPT. It’s a new world. Even though we’ve been emitting carbon for much longer than AI has been around, I think the same is true of our understanding of our role and its impact on our climate. No list is perfect for every person or every project, so putting these lists aside now, I’d encourage you to consider the relationships of energy use and embodied carbon, as well as “now” vs. “later” emissions in your decisions and your projects. And while I know AI won’t be replacing builders any time soon, I think there will be a place for writers and architects for a while yet too.


Lloyd Alter is a former architect and developer. His journalism career includes over 15 years as design editor at Treehugger.com. Today he teaches sustainable design at Toronto Metropolitan University. His work can be found at Carbon Upfront.

19 Comments

  1. user-723121 | | #1

    Harold Orr was in attendance at the 2007 Passive House Conference. Had the great privilege of sitting in with him and about a dozen others after the daily program to see his slide show on retrofits and all things related to residential energy efficiency. He and his colleagues made it work in the cold climate of Canada, timeless, quality information.

    Doug

    1. LLOYD ALTER | | #2

      I met him once when he was in Toronto; what a gem.

  2. Expert Member
    Michael Maines | | #3

    It's interesting how close AI's results were to being useful, yet how far they still are from being accurate.

    Your #5 suggestion is the most challenging to me--while I fully agree that most of us should be living more densely, for various reasons many of us end up away from city centers, where walkable neighborhoods or safe travel zones for e-bikes (or any bicycle) simple don't exist. It's a challenging problem. Do you have advice for people committed to living in rural areas?

    1. LLOYD ALTER | | #4

      An English study found that e-bikes can have the biggest impact in the suburbs and rural areas. "Electrically-assisted bicycles (e-bikes), if used to replace car travel, have the capability to cut car carbon dioxide (CO2) emissions in England by up to 50% (about 30 million tonnes per year).
      The greatest opportunities are in rural and sub-urban settings: city dwellers already have many low-carbon travel options, so the greatest impact would be on encouraging use outside urban areas.
      There is scope for e-bikes to help people who are most affected by rising transport costs." https://www.creds.ac.uk/publications/e-bike-carbon-savings-how-much-and-where/

  3. Jud_Aley | | #5

    Lloyd-
    What about regular old pedal bicycles? less costly than e-bikes and no battery issues.

    My office is 7 miles away from my home in suburban Norwalk CT. If I dont have any morning appointments I'll often ride my pedal bicycle to the office and back. A 14 mile round trip may sound like a lot to many people but after you do it a couple of times you will realize its really not that much effort, I ride at a very leisurely pace taking about 40 minutes in each direct. And i get some good exercise.

    My bicycle has a generator front hub that powers a LED head light and tail light and soon I will add a USB charging port to charge my phone while I ride. If anyone is interested in generator hub lighting systems look up Peter white Cycles in N.H.
    you will find everything you need.

    If you want to bicycle commute all year, in the winter, you can get studded winter bicycle tires. I have an architect friend who uses them for his winter bicycle commute.

    Having said the above I know most people will go for the E-bikes, the temptation of convenience and human nature to avoid physical exertion is to great.

    Great article, thanks for writing it. - Jud

    1. Expert Member
      MALCOLM TAYLOR | | #6

      The problem with both e-bikes and pedal ones in rural situations, it that even if the residents do white collar work, their trips to or from home usually involve moving cargo of some type.

      1. LLOYD ALTER | | #9

        The big change with e-bikes is that they are evolving for this; most people are buying "utility" designs that can carry a serious amount of stuff. They have smaller, fatter wheels that you would never have on a regular bike and can carry a lot of groceries or tools. A sheet of drywall is problematic, but my house renovation was done by a firm where the carpenters and labour who worked for the company biked here. Subs drove pickups. Look at this Rad bike, this is where the industry is going. https://radpowerbikes.ca/collections/electric-bikes/products/radwagon-electric-cargo-bike

        1. Expert Member
          MALCOLM TAYLOR | | #10

          Lloyd,

          Coincidentally, this morning our provincial government just announced a great rebate program for people buying e-bikes: https://www.cbc.ca/news/canada/british-columbia/e-bike-rebates-bc-1.6855065

  4. bob_swinburne | | #7

    Many residents in and around Brattleboro Vermont have adopted e-Bikes and cargo bikes to accomplish daily tasks including getting the kids to school and grocery shopping. For some, it is a year round thing and for others it is more seasonal. The local credit union has low interest rates on loans for purchasing cargo e-bikes. The steep hills and gnarly conditions on the back roads outside of town are at times too much for any sort of bike and most low slung cars but It doesn't have to be a year round thing to make a big difference.

  5. Jud_Aley | | #8

    If you have a lot of large hills or are hauling kids or Cargo an E-bilke would make sense..

    Where I live its relatively flat, I used to take one of the kids to school via my pedal bike pulling a tow-bike behind. It was not bad, but the biggest hill was only about a 2o' elevation and Jake's pedaling ac helped a lot.. Photo attached.

  6. capecodhaus | | #11

    I cant imagine how unsafe for a good majority of people the practice of biking to commute regardless of propulsion system the bike equipped. Most roads especially rural are not set up with any safety margin for pedestrian traffic, and most people that drive exhibit reckless behavior short on time and patience. That last thing a person cares about on the road is another person/pedestrian.

    Before touting the benefits of near carbon free travel, calculate the footprint for the ambulance and clean up crew that has to collect the remains of a person from the roadway. I've cleaned up plenty of toes, fingers and bits of cranium left behind from accidents, the pieces too small get hosed off into the ditch for the crows to pick at. Maybe we should stop supporting building mega mansions etc, before resorting to splitting hairs to save a few pounds of carbon.

    1. Expert Member
      Michael Maines | | #12

      One simple solution is to pave wide shoulders. I wish the roads around me had paved shoulders, but it's simply not safe to ride a bike here. There is a cost, both financial and carbon, to paved shoulders but it would go a long way toward solving the safety issue.

    2. joenorm | | #13

      It's in all likelihood statistically safer to ride a bike on a shoulder than to drive that same road in a car. I don't have any stats to back so it's just a guess.

      1. Expert Member
        Michael Maines | | #14

        The shoulders here are narrow and soft, and large pickups with wide mirrors are the most common form of transportation. Statistically you might be right, but sometimes it's just not possible to ride on shoulders, at least not at more than a crawling pace. When I was a kid, growing up nearby, we biked on the roads but drivers were slower and more respectful, and vehicles were much smaller. A small group of kids has been riding on the road in front of my house and every time they go by--following the rules--they get honked at. There's a culture issue as well as an infrastructure issue, especially for those of us living away from cities and suburbs.

        1. maine_tyler | | #15

          It depends on the specific roads. I'm also in Maine (central), and I have family and friends who are avid recreational road bikers. Some roads are great, others they stay off. Its depends not just on large geographical regions or urban vs rural, but road by road. They do know how to ride on the road with cars— it takes discipline and understanding, especially with the, um... culture, that you mention.

          I occasionally biked to school back in elementary (about 4 miles one way). I now live in the same town, but I could not possibly bike to work, for which I drive all around the county. Maybe an electric motorcycle, but I would need to figure out how to slim down my traveling tool kit by quite a bit.

          1. Expert Member
            Michael Maines | | #16

            If I recall correctly, you're on the other side of the Kennebec River from me. The roads are different, perhaps partly a result of the higher per capita income on your side of the river. Try riding the back roads of eastern Kennebec County, Waldo County or Lincoln County.

          2. maine_tyler | | #17

            I don't doubt it Michael. Ultimately, whether riding a bike for commuting (or other) purposes is practical/safe just depends on lots of very local factors. Fortunately, for many Americans, it probably IS safe, even if not for all of us. Whether it's practical is probably a different matter. Our society moves at a clip, powered largely by oil. We will need to make significant cultural changes to accept a slower pace of business.

  7. jollygreenshortguy | | #18

    I am pleased to see comments regarding bicycles. I "straddle" the fence in that I am unable to ride one due to physical limitations, but also very much advocate for their widespread adoption.

    It is true that bicycles are not the one perfect solution for all our problems. (There is none.) But communities could do vastly more to accommodate them and encourage their use, and in doing so, have a positive impact on our environment.

    So, whether or not they are the solution for us personally, individually, let's recognize that they are indeed a solution for many and should be encouraged.

    1. Tim_O | | #19

      Do I remember right that you are temporarily living in France? Some of the European cities have done a great job of adopting bike culture. I imagine the cities in France have as well. Last summer, we travelled to the Netherlands, where bikes rule the road. There were so many, it was amazing. In cars, you have to be constantly vigilant, but people there are. You yield to the biker, no questions asked. As noted in some of the above posts, American drivers have some sort of disdain for bikers.

      By me, there are a few roads where bike lanes have been added as an extension of the road. People treat them like it's a turn lane for cars.

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