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Green Building Blog

A Look at Low Carbon Homes

Brian Hayes and Michael Maines are among a small number of building pioneers who are beginning to consider embodied carbon in their projects

“If you are building a house in 2019, all of the embodied energy gets burned this year, which means that all of the carbon associated with that embodied energy is going into the atmosphere this year.”—Martin Holladay

Still abuzz after our recent Building Science Summit, I’ve recommitted to a rallying cry I haven’t sounded loud enough. I’m not alone in that department. Though the dialogue around embodied carbon is starting to attract more attention, the green building community is still primarily focused on the operations-related environmental impacts of our houses, so efforts are centered around energy efficiency over the carbon emissions associated with residential construction.

At the summit, designer/builder Michael Maines talked about The Pretty Good House 2.0; he described Bruce King’s book, The New Carbon Architecture, as his building bible. I ordered a copy immediately and have been thoroughly engrossed ever since. I spoke with Maines about the subject, and during our conversation he mentioned Brian Hayes, owner of Bellwether Craftsmen in Huntington, Vermont. Because Hayes is committed to low-carbon building materials and methods, I called him up to hear his thoughts on this budding movement.

Hayes began his career erecting barns and farm buildings before moving into the residential sector. He is an expert timber framer and is Passive House- and CPHC-certified. In other words, he is a craftsman with a conscience. “My motivation for low-carbon, high-performance, natural building is socially and environmentally based,” he says. “It’s just the right thing to do on so many levels. We know better. We know we are doing bad things, and we are doing them because of exploitative economics. I’m not into it.”

One of the driving principles behind a low-carbon home is that it should be small. Maines has specified 1000 sq. ft. for one person, 1500 sq. ft. for two, 1750 sq. ft. for three, and 1875 sq. ft. for four. “If it is well designed, people can fit into a lot less square footage than they believe,” Hayes notes. “There’s a whole client education piece to this. We tell them: ‘We can build you a high-performance, natural, healthy building that is going to be durable and sustainable but to get there, we have to reduce square footage.’”

Hayes strongly believes the 30-year standard and the code minimums based on it are sorely insufficient, and essentially produce “disposable housing.” He designs and builds homes with a lifespan of 75 to 100 years using roughly 90% natural materials. He cites vapor permeability as critical to a building’s performance, saying it has the biggest impact on durability. Hayes advocates for vapor-open assemblies that can dry in both directions, and says that natural buildings omit the impervious surfaces that result with synthetic materials. He does, however, concede to relying on synthetics for membranes and air-sealing adhesives—because there aren’t any natural alternatives. Pro Clima products (Intello to the inside, Solitex on the exterior) are his current go-to. And 475 High Performance Building Supply is a regular source.

Hayes demonstrates the success of his approach by recalling two projects that had him competing with SIP construction, which promises a level of performance Hayes matches. “Our projects met the standard for Efficiency Vermont 2.0. We went up against a SIP assembly with our 2×6 wall, cellulose cavity insulation, and Gutex exterior fiberboard. That’s all plant-based material—except for the membranes,” he says, adding that plant-based building materials exceed petroleum-based systems in terms of durability and performance. They also create a carbon bank that reduces atmospheric carbon counts.

Operationally speaking, Hayes’s shop runs on solar energy; he builds modular components as much as possible, which limits vehicle trips back and forth to the site; and five of his employees live in the same town as the shop—the sixth has a 20-mile commute. “Using our shop is our best option for keeping daily emissions down,” Hayes explains, adding that he also uses local sources for timber and siding, thereby cutting shipping emissions. “We are lucky to have just about every material we need right here in Vermont,” he says. “We try to use local wood species for everything, and we trace materials that come from outside Vermont—such as FSC-certified fiberboard and cellulose.”

Asked what technologies, if any, he finds useful for building low-carbon homes, Hayes names the Passive House Planning Package (PHPP) and WUFI energy-modeling software. “They are great tools but I think they need to be developed to be user-friendly and a little more available to builders.” However, he questions whether or not further technological advances would be beneficial. “I don’t think we necessarily need more technology,” he explains. “We need more education around the technology we have. And we need to make it standard and regulated—if we do that, then prices will come down, and people will be more familiar, less apprehensive. There will be better executions, better products, and healthier people and buildings.”

So, what exactly is a low-carbon house?

According to Maines, a low-carbon home should:

  1. Be as small as possible—ideally with multi-family or multi-generational occupants.
  2. Be PV-ready or include photovoltaic panels. PV-ready means designed, built, and sited in such a way that a reasonably sized photovoltaic array can handle all of the home’s energy needs on an annual basis. (PV panels pay their carbon debt in 2-4 years.)
  3. Be simple and durable. Simple shapes are easier to air-seal and insulate. They perform better in harsh weather, and require fewer materials and less maintenance than more complicated buildings. If you need to bring in a structural engineer, your design might be too complicated. Invest in the parts that are hard to change later.
  4. Use wood and wood-derived products as construction materials. Just make sure the wood is sustainably harvested—locally, if possible. Otherwise the trees are better left to remove CO2 through photosynthesis. In general, the more materials are processed, the higher their carbon footprint.
  5. Use air-source heat pumps. Mini-splits can be efficient to -15°F or below. They are affordable—especially for the sizes needed in a Pretty Good House 2.0—and they are relatively simple to install. For those who can’t stand the look of an appliance on the wall, there are slim-duct, ceiling cassette, and floor-mounted versions. However, the wall-mounted units are the most efficient, so learn to love them. Heat-pump water heaters are a no-brainer for most homes.
  6. Invest in the envelope. Insulation and air-sealing should be good enough that heating and cooling systems can be minimal, with indoor air quality and comfort levels that are very high.
  7. Be affordable, healthy, responsible, and resilient.
  8. Reflect the “KISS” principle (Keep It Simple and Safe). The house should be easy to operate and understand. Owner-proof systems should omit operator influence and/or error.
  9. Consider time-tested sensible strategies such as planting deciduous trees to shade the south and west walls (in the cold months, the leaves drop, letting natural light in), cooling with fans and natural convection rather than air conditioners, heating water with a wood stove, and air drying clothes.
  10. Be part of a sustainable community. Having access to community solar, jobs, and services nearby minimizes driving and enables the sharing of infrastructure costs. A home in the middle of the woods often comes with a bigger carbon footprint than a community-based home.

Hayes says the 1800-sq.-ft. house pictured here meets the great majority of all ten requirements.

Additionally, Maines says a low-carbon home should minimize or avoid:

  1. Concrete, which contributes 10% of man-made global warming emissions, partly through fuel to heat and move minerals, but 60% from release of carbon dioxide (CO2) from limestone (CaCO3) to get calcium oxide (CaO) for Portland cement.
  2. Foam, especially HFC (hydrofluorocarbon)-blown closed-cell spray foam and XPS (extruded polystyrene) rigid insulation. When building a new house there should be no need to use foam above grade.
  3. Combustion appliances, especially those that burn fossil fuels.
  4. Unhealthy materials.

In Hayes’s house, items 1-4 have been addressed, as the structure is slab on grade with frost walls. “This particular home is largely comprised of natural carbon-sequestering materials—wood, wood fiber, and stone,” he says, adding that he is waiting on the results of a pending carbon analysis for this house, as well as another constructed last year.

It gives me hope that a few builders, like Hayes, are having their projects analyzed for embodied carbon. Because carbon is the next frontier.

-Kiley Jacques is design editor at Fine Homebuilding magazine. If you have a project that might be of interest to our readers, please send a short description and images to [email protected]. Photos courtesy of Brian Hayes.

For more on embodied carbon:

58 Comments

  1. User avater
    Jon R | | #1

    I completely agree that we need to move away from focusing on energy and think about environmental damage, embodied and operational. Current energy focused building codes allow one to install a coal fired furnace and XPS insulation.

    > what exactly is a low-carbon house? ...

    Much more accurate than a list of generalities is a house where you calculate the carbon and it is low. How many tons for the above house? What $/ton was used to determine where to stop?

    Note that focusing on the house alone leads to inefficient allocation of money to reducing environmental impact. Compare your $/ton to other options.

    1. User avater
      Michael Maines | | #2

      Jon, I agree that actually counting your carbon footprint would be a good approach, and when my article on the Pretty Good House appeared on the NESEA website, engineer and energy expert (and author of the "Thriving on Low Carbon" blog) Marc Rosenbaum had a similar comment. But as I'm sure you know, accurately determining the carbon footprint is no small task, and when most builders and homeowners find code minimum to be a stretch and even architects who profess to be "green" still don't know the differences among closed-cell foam blowing agents, I'm not sure your approach is realistic.

      The appeal of the Pretty Good House concept seems to be in its simplicity. If there is an easy and simple but accurate way to find your carbon footprint, compare options and the relative costs of all the variables, I would like to know what it is. In the meantime, generalities are a lot better than nothing.

      1. User avater
        Jon R | | #3

        > generalities are a lot better than nothing.

        More environmental impact optimization software (eg, BCopt vs BEopt) should help the "I can't be bothered with math" designers. Just click the "XPS" box and see the tons go up. IMO, it doesn't need to be very accurate to beat generalities.

        1. User avater
          Michael Maines | | #4

          That's a great idea, Jon. I know there are carbon-accounting websites but I don't know of any that would be comparable to BEOpt. There's a business idea for someone!

    2. Peter L | | #6

      We are nowhere near being able to calculate, let alone enforce, how much carbon it takes to build a home.

      I have to disagree with you that we, "need to move away from focusing on energy and think about environmental damage, embodied and operational". Your killing the horse that will pull the cart. It's hard enough to get local building codes to even enforce better energy efficient building methodologies.

      Commercial airplanes will generate 43 gigatonnes of pollution in the next 20 years. Solution is simple, people need to stop flying as much. Reality is that people will not stop traveling and flying. If anything, it will only increase over time.

      Point is that the building industry is slow to change. Getting them to get on board with just making homes more efficient has been a decades long battle with little to show for the effort. Even so, progress was made and to scrap that and to up the standard to some type of carbon-based calculation when building a home is beyond the scope of any local building department or 99% of contractors out there. Geez, we can't even find good carpenters, skilled labor and tradesmen in 2019, as they are in short supply since everyone is moving towards the IT marketplace.

      1. User avater
        vap0rtranz | | #9

        >Solution is simple, people need to stop flying as much. Reality is that people will not stop traveling and flying. If anything, it will only increase over time.

        I and my team travel for work and a coworker's daughter, whose in her late teens, rebuked her mother (and indirectly everyone on the team, including me me) for flying so much. Her daughter's reasoning was simple, and needed no math: why were we flying around weekly given what we now know about drilling and combusting fossil fuels?

        I'm not convined that future generations are like past generations when it comes to the environment.

        History has some precedence. It does take a long time, usually many generations, for society to change direction, but it does change. My parents, for example, grew up in segregated public schools -- they did not socialize with "those people" -- and that was a commone experience for many Baby Boomers in the US. That's a completely foreign experience compared to my time in public schools, which were very colorful. And my father has no issue burning a gas or oil furnance and driving a diesel truck -- he gives it no thought -- but I switched to heating with mini-splits and a plug-in electric car -- small changes that our household could make that we believed were better long-term. I'm not blind to the fact that EV batteries still present challenges in mining and recycling, or that the refrigerant in heat pumps isn't eco-friendly, but it's an incremental change for the better. Those differences between my father and I are just one generation of change. My coworker's daughter is the next generation.

        So we aren't on the perfect track but we have made incremental changes, that are accelerating. For example, I push back on my manager, and question whether our team really needs to make another trip to be onsite; and when I do have to be onsite, I find compromises like: taking the train instead of a plane, even if only do-able for certain legs of trips, and car-pooling when onsite instead of everyone getting a rental car, etc. We are in the "IT marketplace" that you've accused of stealing jobs, but it is IT that has heavily pushed for remotees and home offices and to get away from problems that factories and offices created, like everyone driving a single occupancy, fossil fuel combusting car to work.

        IT and technology has many, many problems but has pushed society to getting folks _back_ to working from home offices, like past generations had done, so that we're not stuck in traffic commuting to work, so we gain more time to garden or cook at home, less time at the "factory" or commuting to the office also means more time with the family, or friends, etc. I expect the next generation will go further than my generation has and will push us to change more rapidly than we expect.

        1. John Clark | | #16

          Co-workers daughter is naive due to a lack of life experience. Like Greta in Sweden she has no clue what it takes to cultivate long lasting business relationships which support the standard of living she's accustomed to.

          Typically when these young adults become disgruntled they blame someone other than themselves and elect politicians to redistribute the resources of others.

          1. User avater
            Michael Maines | | #20

            Or perhaps she has a valid point--many of us do just fine with minimal air travel. Every action has consequences, some bigger than others. Perhaps one of every three site visits could be replaced with a virtual meeting.

          2. User avater
            vap0rtranz | | #57

            John,

            Well sure, it is naive to think that global travel just began with the advent of an aeroplane. History tells us that even John Adams sailed to France to establish diplomatic relations. And was it caravans before ships?

            Her point is the footprint, not the human connections. John Adam's ship _sailed_ -- that's wind power. Sure those ships back then were built from timber, but after that build it needed no mining for coal or drilling for oil to ferry folks across the pond. Much cleaner option than today's fuel efficient turbine aircraft. That's the point.

  2. Kristin Green | | #5

    That is a beautiful house! I'd love to learn more about the foundation and insulation used. The benefits of slab-on-grade vs. carbon costs of concrete is a discussion that interests me. Are those TJIs (Larsen Trusses) I see on the roof? What was used to insulate them?

    1. User avater
      Michael Maines | | #32

      Kristin, I believe the foundation is more or less a typical slab on grade with turned-down footings, insulated with recycled XPS. The carbon accounting for slabs vs. other systems is complicated, and Advantech, the subfloor most builders I know prefer, has a significant embodied carbon. My rule of thumb is that the lowest cost system for a high performance home is a slab on grade with exposed concrete floor. When clients don't want a concrete floor it makes sense to look at alternatives.

      The roof is framed with traditional large timbers, sheathed with solid wood planks, insulated with Gutex wood fiber insulation, strapped for ventilation, and then sheathed with OSB as a base for the metal roofing.

      1. Kristin Green | | #34

        I love the look of the large timbers with solid wood planks on the inside! However, I was asking about what is on top of that.

        In picture #5 above, the Gutex is unfinished on the right side of the ridge and exposes what look to be TJIs beneath. That's what I was referring to. Pics #2 and #3 make the roof look too thin to have anything between the wood planks and the fiberboard... that's why I asked. If you did use TJIs, did you dense pack with Thermofiber?

  3. Nick052157 | | #7

    Wow! These are beautiful well thought out houses. The level of preparation and craftmanship is stellar. I love the idea of local materials and eliminating as many synthetic materials as possible, particularly plastics, given the health concerns. Also love post and beam and your siding choices. The only suggestion would be to consider moving away from concrete slabs and stem walls to wood piling or posts with a wood floor a few feet above ground, or if you don’t like treated wood, use thin concrete piers on smaller footings.

    I presume these homes are not in the price range of most young people? . I would encourage you to think about the possibility of taking some of these ideas and incorporating them into lower priced homes so they can have a wider impact. I have been toying with th idea of using pole barn style buildings converted into efficient homes. I like the idea that the initial envelope can be mass produced and then modified on site. Imagine a hybrid, where talented builders like you could create a local factory ( ie a larger “shop”) and build the envelopes from local material. Then deliver to the site and construct them. Other less talented subs could then do the interior finish work. If this model replaces even 10% of the track housing going up in the vicinity, it would have a significant impact on reducing emissions in that community.

  4. Russell Miller | | #8

    Wonderful article!

  5. Rick Evans | | #10

    "Just make sure the wood is sustainably harvested—locally, if possible".

    I am intrigued by using locally sawn green lumber. I remember reading a post on GBA by Robert Riversong about how full dimensional green lumber is considerably stronger than KD lumber.

    Does green lumber shrink considerably? Can you nail plywood sheathing to it and tape it? Will drywall crack as the green lumber dries out? Still use a PT mud sill?

    Thank you and great article!

    1. Malcolm Taylor | | #11

      Rick,

      I'll let Kiley or Micheal comment on the house and framing, but to Riversong's assertions about green-wood:

      Of course full dimensional lumber is stronger than nominally sized pieces, but kiln drying doesn't affect the strength of the lumber - at least not in a negative way. Controlled drying avoids cracks and twisting that can reduce the strength, and in any case all the framing lumber, whether green or KD, will over time reach the same level of moisture in equilibrium with the ambient conditions.

    2. User avater
      Michael Maines | | #12

      Rick, we'll be talking about using locally-sourced wood and wood products at our BS* + Beer (*building science) discussion group in Liberty, Maine on 12/19. Robert Riversong lives nearby and sometimes attends; I bet he'll come to this one.

      Green lumber does shrink, but it's how most US buildings were built before kiln-drying and trucking long distances became a more affordable alternative. Eastern hemlock in particular is famous (among wood nerds) for being easy to work with when wet, and "locking in" fasteners as it dries.

      Fully saturated wood is somewhere between 25-30% moisture by weight, typically kiln-dried to 18-22% partly to reduce fungal damage but mainly to reduce shipping weight, and in New England will eventually end up at 6% to 14% moisture, depending on the season. In Bruce Hoadley's book, "Understanding Wood" there are formulas and constants for shrinkage rates of different species and flat sawn vs quarter sawn lumber. I'd estimate a typical rough-sawn 2x6 stud might shrink 1/4" to 3/8" and a 2x12 about 1/2" to 3/4" as it goes from fully saturated to equilibrium with ambient conditions. Movement is primarily across the grain; wood moves little along the grain. So yes, drywall cracks could be an issue if you don't wait for at least some drying to occur.

      When calculating the stiffness of framing lumber, usually the most important measure of strength, the values for wet lumber (such as deck framing) are derated compared to dry lumber--called the "wet service factor." Plus kiln-drying changes the properties of the perimeter of a board, called "case hardening," which makes the wood more brittle but stiffer. So dry lumber is essentially stronger, in the ways we care about for house building. The main difference is that green lumber is typically full dimension, and the depth of a framing member has a large impact on the stiffness of the member.

      All of the images Kiley used are of a house designed and built by Brian Hayes/Bellwether Craftsmen. And I should add that my only personal experience framing with green lumber is a garage I helped my father-in-law build a long time ago; others have a lot more hands-on experience.

    3. User avater
      Jon R | | #15

      > Will drywall crack as the green lumber dries out?

      For green or partially kiln dried wood, I'd add the question "will the air sealing that looked so good during the blower door test be degraded?". For example, that 1/32" inch caulked crack that expands to 1/8" is beyond caulk's rated range.

      1. User avater
        Michael Maines | | #19

        That's a good point, Jon. The high performance homes I have seen that use green lumber also use high-tech membranes and tapes for airtightness, not the structural sheathing as we can do when using kiln-dried lumber.

        1. Brian Hayes | | #28

          Great question Jon, and Michael you are correct we do use vapor smart primary air barriers to achieve our airtightness targets. Details that account for timber shrinkage over time as well as seasonal movement avoiding reliance on caulk joints especially at timber interfaces are mandatory.

  6. Rick Evans | | #13

    Michael, Malcolm,

    You guys bring so much to this community. Thank you!

    Its funny- I've seen "Wet Service Factor" in lumber span calculators. I always assumed it was referring to wood structures (like pergolas) that were located outside and subject to weather lol.

    Glad to hear Riversong is still engaged in the community. Thanks as always for sharing your wisdom, Michael!

    1. User avater
      Michael Maines | | #14

      Thanks Rick. You are correct, "wet service factor" is intended mainly for outdoor structures, but as I understand it, one reason it's there is because saturated lumber is not as stiff as dry lumber. The other reason is that even rot-resistant wood will eventually decay, so the WSF provides a bit of insurance. The second reason is likely more important.

  7. John Prospect | | #17

    I am late to the comments but had a couple questions about Gutex insulation. From what I can see, it seems to perform a bit like a rigid board of 'cellulose' insulation? My concerns are:

    - For fire resistance, what kind of treatment are they using? Borates or ammonium sulfate? Wet ammonium sulfate off-gassing is not much fun. The PDFs on the Gutex site that I looked at say Euro class 'E' fire rating, which is quite flammable.

    - For water absorbancy, does it act like cellulose (hydrophillic) or rockwool (hydrophobic)? The differences may be important when used as exterior insulation in a humid climate.

    - What is the carbon impact of shipping low-density wood fiber from Germany to North America?

    I enjoyed the article. Even if this solution is not perfect for everyone, I think aspirational projects help us all think more about what we are doing.

    1. User avater
      Michael Maines | | #18

      John, here is an article I wrote as an overview to wood fiber insulation: https://www.finehomebuilding.com/2019/05/08/284-in-favor-of-wood-fiber-insulation. Scott Gibson wrote this for GBA at about the same time: https://www.greenbuildingadvisor.com/article/fiberboard-insulation-developer-takes-step-forward.

      To answer your questions:
      The rigid product (comparable to rigid foam) and batt product have no added flame retardant. It is intended for use in otherwise fire-protected locations. There is also a loose-blown product, similar to blown cellulose or fiberglass, that includes a flame retardant. The blown product about to start being made in Maine will have a borate additive, the same as high-quality cellulose. Wood itself is rather flammable, and I have caught XPS on fire on a few occasions when soldering copper pipes nearby. I would be leery of using exterior wood fiber in a fire-prone area, but it really shouldn't be a concern in most places.

      The wood fibers are hygroscopic and hydrophillic, but when used in rigid panels they are combined with varying amounts of paraffin wax that provide water resistance. The panels are also vapor-open so if the insulation gets wet it can readily dry.

      Gutex and Steico are both made in Europe using well-managed forests within 50-80 miles of the factory, rendering it a strongly carbon negative material when used in Europe. When shipped to the US in bulk and used close to the port of entry, as a primary insulator (meaning it's doing a lot of insulating, not adding R-5 to a wall that's already well above code-minimum) it can still be carbon negative. Once you start trucking it around the US you lose the carbon-negative status but it's still a lower-carbon choice than most of the alternatives.

      I still have not installed it myself, but hopefully will this spring. Builders I know who have used it say that the rigid product is easier to work with than foam, and has other advantages as well.

      1. John Prospect | | #29

        Michael, thank-you for the links and information. Anything that is able to use wood more efficiently has to be a good thing, if forests are managed well. Good news that someone is now making it in Maine.

        Unfortunately, I live in a place with serious wildfires:
        https://en.wikipedia.org/wiki/2017_British_Columbia_wildfires

        That year an area about 13% the size of Maine was burned. The next year even more area burned, but in less-populated areas (luckily). I am also not a fan of foams. For fire resistance, my first choice is rockwool, even if it requires some energy input for manufacture.

        I will be curious how the rigid panels perform over time. Blown-in cellulose seems to be a better (down-cycled) product for in-wall use, and I am cautious about exterior use of wood-fiber from both a fire and moisture standpoint. I would happily be proven wrong, though!

        Keep up the great work.

        1. User avater
          Michael Maines | | #30

          John, wood fiber insulation has been around since the 1930s, in regular use in Europe since the mid-1990s, and now has about 8% of the European insulation market. While it's always safest to wait 50 years to see how a product really performs, there is enough of a history in Europe to make me comfortable in most situations. I would be careful in fire risk areas or high moisture areas.

          I'm a big fan of cellulose, but the product quality and availability have been going downhill for a few years--news print is not a growth industry! And from what I understand, carbon footprint calculations for cellulose typically start with the newsprint as a zero-carbon material, when in reality it took energy (and carbon emissions) to create the paper. Most of the newsprint used in cellulose manufacturing is post-industrial waste, meaning pre-consumer waste. With enough post-consumer product to have serious contamination problems. Wood fiber skips the step of making the paper, saving carbon in the process, and logic would suggest that it should be easy to get a consistent product.

      2. Burninate | | #49

        Did the math on trucking the other day; It seems getting something from Los Angeles to Maine via truck (5000km) is on the order of 20 tons of CO2 per 40 tons of freight. Getting it from Europe to Boston via ship runs about 1 ton of CO2 per 40 tons of freight. Getting it from Europe to Hong Kong to Los Angeles is around 3 tons of CO2 per 40 tons of freight.

  8. Irene3 | | #21

    An obvious way to make more affordable and even greener options is to use the same techniques in multifamily buildings -- duplexes, triplexes, semidetached or row houses, etc.

    1. User avater
      Michael Maines | | #22

      Irene, I agree, and that is meant to be part of the #1 Pretty Good House item: "Be as small as possible—ideally with multi-family or multi-generational occupants." But I understand if the full intent was not clear.

      1. Brian Hayes | | #27

        Absolutely agreed Irene. We really work hard to keep budgets in line for a single family residence using these techniques, but it is possible. With that said I believe these materials and methods would be particularly beneficial for multifamily dwellings.

  9. James Morgan | | #23

    "He designs and builds homes with a lifespan of 75 to 100 years"

    What does this mean exactly? Will the house magically disintegrate like the marvelous one horse shay when its allotted time is up? The reality is that ANY code-minimum house built today should have no problem lasting that long if the land they are sitting on does not become more valuable as an empty lot, while a well built, decently designed and wisely located home should be capable with simple maintenance and modest periodic upgrades of retaining its purpose and functionality for hundreds of years. Why do we set ourselves such a low bar?

    1. User avater
      Michael Maines | | #24

      James, I've talked with Brian about this a bit, and I think he was somewhat misquoted. Today's production, code-minimum homes are designed to last 30 years. Obviously the frame and foundation will last longer, but all of the interior and exterior finishes, the roofing and windows, and all of the equipment will need to be replaced within a 30-year span. Some components only last a few years. I've done a lot of remodeling and rarely (or never) find a house without moisture damage of some sort.

      Brian, on the other hand, builds so everything about the house is durable, and if it does need to be replaced, the frame can stay intact. Assemblies are vapor-open in both directions so no matter what happens with climate change the walls will be ok. (In 75 years, New England's climate will likely look a lot like Virginia does today, which will wreak havoc with assemblies that only dry outward.)

      1. Brian Hayes | | #25

        The notion of a 75-100year build standard is an aspirational target predicated on two main objectives: design and construct with the intent to meet or exceed replacement life span for fibrous material inputs for any particular structure, and disrupt the exploitive economic dynamic pervasive throughout the industry that has promoted, possibly encouraged, the manufacture of poor quality, inefficient, and unhealthy housing contributing toward injustices both social ( occupant and worker health ) and environmental ( highly persistent toxic building materials ). From my perspective the path is clear, emphasize the use of plant based materials, de-emphasize the use of materials with high counts of embodied carbon, toxicity, and environmental persistence. While I certainly do not have all the answers, striving to always learn and evolve, my experience has shown me that properly detailed vapor open assemblies contribute significantly towards durable healthy buildings and the environment. If we can increase the service life expectation for our structures, address the points of occupant health and comfort, while delivering a high performance building using sustainable practices and materials, my feeling is the service life cost analytics or value to cost ratio, would be a stark contrast to the multiple 30 year loan terms assumed for homes constructed under current build standards and practices.

      2. James Morgan | | #33

        "all of the interior and exterior finishes, the roofing and windows, and all of the equipment will need to be replaced within a 30-year span"

        This is a wild exaggeration based on building for the duration of a standard thirty year mortgage. It's like saying my car has a design life of five years because it'll take that long to pay off the note. Roofing I'll give you. Asphalt shingle roofs are expected to be replaced regularly like the tires on my car. As for mechanicals, in even the best built homes no one expects a heat pump to last more than thirty years and after only ten or twenty years a replacement unit might seem attractive if it uses half the energy. Other components: kitchen and bathroom cabinetry, tile and equipment are more likely to be replaced on account of fashion than failure, yes even a home as well built as this can expect such makeovers under subsequent owners with different tastes. And the reality is those so-called thirty year homes are extremely likely to be there for generations. I look out my office window at a row of cheaply built millworkers' cottages from the 1920's that despite long periods of neglect and deferred maintenance and despite being built only a foot off the ground with wildly overspan floor and ceiling joists and rafters have never gone out of use and continue to be highly valued. In the surrounding neighborhoods are hundreds of developer-built homes from the 1950's, 60's, 70's and 80's, from brick ranches to two story mock colonials and transitionals. All of these are well past their throwaway date according to this thinking, most them built to a lower standard than contemporary homes, to less stringent codes or to no code at all, and all still vibrant, fully occupied and attracting ongoing investment in upgrades and additions. Single pane windows will be replaced with better performing insulated units that were simply not available at first build. Incandescent lighting will be replaced with LEDs. Roll in showers will be installed because of the needs of aging and infirm occupants. The reason for the ongoing vitality of these homes is not how well they are built but where they are built, as part of a sustainable and healthy community. There are no throwaway houses: there are only throwaway unsustainable developments. I thoroughly welcome the focus in this particular new build project on the issues of embodied energy and embodied carbon emissions in new construction, both of which tend to be undervalued in the gallop toward better energy performance in use, but let's not forget that the greenest brick is already in the wall, and also let's not forget that our most important task is not building houses or even building homes, but doing our part in building connected physical communities that have a fighting chance of sustainability. It's going to take more than electric cars and super low carbon homes to deliver us from the pernicious effects of exurban sprawl.

        1. Brian Hayes | | #35

          James,

          25 year design life applies to most U.S. windows, all asphalt shingles, vinyl siding, on and on, etc. . I am willing to bet the older resilient houses you describe share an important attribute as originally constructed : the ability of the building assembly to dry -- speculating a bit further I would wager they also share a lack of comfort for the occupants, poor indoor air quality ( health issues ) , low energy efficiency, mold, mildew, environmentally persistent and toxic materials, etc. I have certainly paid my dues over the years working on buildings from the 1750's to present. While I have certainly not seen it all, one clear observation in hindsight is that older buildings comprised of mostly natural materials and having the ability to dry are indeed long term durable... 50 -200 + years...nothing like learning from the past. The problem with these old durable buildings is lack a of comfort and energy efficiency ( think operational carbon ). In this way we are fortunate to have the knowledge and materials to sustainably design and build our additions, remodels, retrofits, and new structures while improving occupant comfort, health, with positive inputs to the environment. While I do believe there is wisdom in the notion of " there is no greener home than one already built " we have to admit there is plenty of room for improvement moving forward, especially in regard to the use of environmentally persistent toxic materials. It is important to note that most of our sustainable materials embody or sequester carbon. I say this after a day of working on a 9 year old home, designed from the principle perspective of net zero energy efficiency, enclosed using a synthetic thermal assembly, currently in a substantial state of failure and dysfunction. The really hard truth is that this scenario is not uncommon. I stand by the assertion that our current construction standards and conventional materials serve the economic interests of the building industry at a detriment to our social and global environments. Simply put we can and should do better. Assuming regulation and corrective action is not going to intervene anytime soon, the onus falls to those who are compelled toward change. I personally commit, advocate and work towards alternative arrangements and standards in support of the people, the planet, and profits in that order with the understanding its not a good fit for everyone. I agree with James that it will take a whole lot more to deliver us -- Integrating holistic considerations to our design parameters and building strategies must be a worthwhile step in the right direction.

          1. James Morgan | | #39

            Substantial failure and dysfunction after nine years. Wow, I feel your pain. This is why I am extremely cautious of whizz bang 'innovative' solutions that promise miracles. I'm currently looking to establish partnerships with younger contractors as my long trusted and highly experienced building partners are aging out, and again and again I find their answer to any insulation and air sealing issue is to spray foam everything.

            I could not agree more about the remarkable durability of drafty old buildings, and building or renovating to contemporary comfort and energy performance standards without compromising that durability is challenging.

        2. Burninate | | #50

          Three points:

          * We're building out of more moisture-sensitive materials than previously

          * We're building for far more energy efficiency than previously, and energy efficiency increases moisture management concerns

          * You're talking about houses that have seen abundant work done to address problems. When a roof leaks, you patch it. If you fail to patch it, you might have to replace the roof. If you do: Did the roof last X years? Would you say the house lasted X years? There's a Ship of Theseus issue here (or if you prefer: My Grandfather's Axe).

          Those houses are well past the timespan when important things about the house are going to have to be replaced. That's all it means. This only corresponds to a "throw-away-date" if you have zero/negative population growth, like Japan - where indeed, houses are a relatively inexpensive, depreciating asset, and most people buying new single-family homes do complete teardowns.

          If you have rapid or even moderate population growth, it's nearly always worthwhile for somebody to try to capitalize on sunk costs and try to make the house habitable. In this environment, even if the house is built in someplace that's entirely socially useless, like a West Virginia mining town on the site of a closed mine, you can probably fix it up and sell it to some retiree looking for a place in the country, or someone willing to put up with a three house commute. Depopulating this sort of town as a social service, and erecting a town-sized neighborhood in a walkable city with a functioning economy, is one thing that's probably necessary for a low-carbon future (due to transportation CO2), and it's entirely taboo in American politics.

  10. Tyler Keniston | | #26

    It's nice to see a nod to 'where to build' for efficiency.

    I sense people are a bit 'over' the hippy-commune mentality, but I do wonder if we'll come at least partial circle to the notion of community-scale living and begin reinvesting in the mid-sized towns that once thrived with localized production.
    Perhaps its at least a weight on the scale when deciding if retrofit work, despite the labor and sub-optimal baseline, is worth undertaking vs building new manicured homes in the suburbs or sticks.

    1. User avater
      Michael Maines | | #31

      Tyler, I'm seeing the reinvestment in mid-sized towns here in Maine (where we call a village of over 15K people a city). Augusta, Waterville and Belfast, all economically depressed mill towns until a few years ago, are seeing an influx of investment as people from other places realize that a small city can offer most of the benefits of a big city, without the congestion.

    2. Burninate | | #51

      Mid-sized towns that once thrived with localized production were built in a time when transportation was inordinately expensive, international transportation on a large scale was essentially impossible, vast untamed wilderness was available to build on, and production was labor-intensive and largely unskilled.

      That's no longer the case. The way the global economic system works now means that the smallest functioning economic unit is a large city, and the largest is a megacity. Everything else is either a land-intensive industry like agriculture (which is heavily mechanized / low-labor nowadays), a resource-specific extraction industry (which are now also heavily mechanized / low-labor nowadays), or some kind of drain on the national coffers that is kept alive mostly through redistribution of the economic productivity of a city. This is a balance of payments argument (which you saw illustrated so well in Germany vs Greece vs the Euro); Different regions functioning on the same currency will eventually lead to that currency accumulating in the region where it is most productive, absent some form of non-market redistribution, labor migration, or remittances.

      Whole states no longer make much of any economic sense to live in, but we haven't noticed because we have lots of redistribution going on. Lots of Medicare to hand out, lots of hospitals to build, lots of SSDI checks going out, food stamps to spend and supermarkets to spend them in. Carbon taxation is not strongly progressive, and impact rural areas dramatically more than urban areas. This is part of the reason that the Green New Deal is such a broad policy constellation: Because depending on the texture and specifics of carbon policies these places could easily be made either impossible to live in (causing a massive protest / civil war like the Yellow Vest Movement), or far too attractive to live in (causing a vast expansion of CO2 emissions). The GND should ideally gradually shift this population by providing them both incentive and a degree of compensation.

      1. Tyler Keniston | | #54

        "The way the global economic system works now means that the smallest functioning economic unit is a large city"

        Really? Can you expand upon what constitutes a unit and why a small city or large town is not even particulate to the global economy?

        To add a bit to my 'mid-sized' town comment: I didn't mean to suggest we go 'back' to a production model, only that the scale may be utilized with a new economic model.
        A layout (if one were to design this) that seems sensible to me is a somewhat European one where there are more but smaller cities surrounded by resource 'green' zones and interconnected by efficient mass transit. I understand the 'per capita' energy use benefits of a city, however I don't see why they need to be the 'big' cities for this benefit to occur?

        I might have somewhat of a personal issue insofar as I don't find living in a massive concrete jungle desirable. I appreciate the arts, a good restaurant, etc, but home to me includes something block to block asphalt, concrete, metal, and glass don't offer. I'm not yet convinced we all have to suffer that fate in the name of global warming.
        I'm open to hearing more about why its really the only way to go, but calling cities the 'smallest economic unit' feels a bit hollow.

        A small question: where do you feel 'value' comes from (either economic or otherwise)?

        1. Burninate | | #55

          Note: "City" here includes suburbs, to a degree.

          Big cities just function better for humans at the stage of labor specialization that the modern economy currently employs, and at the stage of market specialization that people aspire to enjoy.

          As the tide of general manual labor tasks recedes, you end up with a number of very specialized roles which require a lot of training. In a small town, for these roles, there are likely zero local applicants already in place; So every hiring event has to fly in interviewees, import an employee from somewhere else, and effectively buy them a house in the town. Once in place, they effectively own the employee: He cannot get hired for that role elsewhere unless he wants to move. So there's no reason for that raise. If he finds his new boss to be unacceptable, there's no way to move to another position in another company, because the next company that employs his niche skills is six hours drive away. He has to move. Again. Let's say he's happy with the company: Now his specialized skills are locked in to that company's particular setup, and he gets no exposure to anybody else in his role, ever. For him, every town is a company town. There is effectively no easy labor market for him to operate in. Let's say he's a bad employee and the company wants to fire him: They have to find a replacement who's ready to live in the middle of nowhere and dramatically harm his career prospects. This is not cheap. So the goods and services that the company provides are more expensive, and may even cease to be competitive. Let's say that after being fired, our ex-employee doesn't want to move (his kids are in school), and wants to restart his career as a sushi chef, his true passion. Turns out there literally aren't enough people in town that eat sushi to operate a restaurant in it, much less operate a competitive market of restaurants where a sushi chef's skills have a market rate. If this guy had just stayed at his specialized-skills job in the city, and he'd gotten fired, he could have been interviewing the very next day for a similar position at another company across town, or optionally a selection of fifteen sushi restaurants, two of which actually have openings.

          Scale of settlement matters for human opportunity, and for business competitiveness, and to a degree, for value of consumer goods & services provided. Cities are the engines of the post-industrial economy.

          In San Francisco you have a labor market that can accomplish things with software that the entire continent of Europe couldn't accomplish with software. It's a labor-market specialization of that city. In Los Angeles they have a streamlined industry dedicated to filming movies; If you're trying to set up a film operation, you're not going to find a seasoned key grip who just happened to be available for work in Galesburg, Illinois. You're also probably not going to set up a specialty camera lens business there. In Shenzhen they can do things in an afternoon with consumer electronics hardware prototyping that would take a firm in Tampa, Florida months and months of back and forth; They can iterate in Shenzhen because the people they are working with and the supplies they are using and the employees who are making the decisions are all within 30 minutes of each other; A remote assignment to a new supplier might be a lunch hour's train ride away, because fifty million people live within that radius.

          Cities in the US don't get to keep all of the federal and state tax dollars made in the city. A large fraction of those dollars don't get spent in the city. Instead, they get spent propping up entitlement programs in rural areas. When we talk about a lot of American small towns in 2019, we are talking about places that don't really export much of anything. They still consume food, fuel, consumer goods, a whole host of things. They still trade a little bit within the town. But mostly, their dollars are very rapidly draining away to manufacturers of things they are importing, and to corporate owners of retail businesses which have set up a franchise within their limits. The towns are bleeding money, and descending into poverty, unless they have some patrons which export widgets to the rest of the global economy (and the widget builders have to get their hair cut somewhere, and have to buy gas somewhere, and it all trickles down in theory with local spending). All the town has to offer to businesses to locate there after a while are signs of decay - cheap real estate, a low minimum wage, tax breaks which decimate the budget. Walmart is especially bad with this, and once they've set up most of the other businesses close down, and the town stops trading with itself (its economy shuts down) in favor of trading with a corporate patron which takes some off the top of every interaction.

          So instead, a city with a host of functional businesses that brings plenty of money into the area from abroad gets heavily taxed, and a portion of that tax gets funneled to the small town. Let's call it food stamps. The city agrees that poverty is bad, and it covers $100 of everybody's tab at Walmart in the small town. Walmart makes enough money to continue to employ as many people as they employed last month, and it pays enough employees to continue to keep the cycle stable. A town on life support.

          A group of friends who work at a bank in the city retire together, and move into the town to inhabit some of the cheap housing. They're drawing good pensions from the bank now, which gets injected into the economy to counter some of that bleeding, and also they're going to die soon. They're all on Medicare now. When they die, in the last few years of their life, they're going to spend half of the money they'll ever spend on healthcare in their lifetime. Money is going to fall from the sky into this town as if from a strategic bomber. It's going to go to a system of hospitals, doctors, nurses, and care providers. And then it's going to trickle down into the rest of the economy.

          These places were mostly built when we had an extractive, agricultural, or domestic manufacturing economy in this region. For the most part, we don't any more. People spread out into them because people could make a living in them, off the sweat of their own brow. The only reason anybody still lives there is cheap, old, inefficient, spread-out housing. They only reason anybody can afford to is that we've invested trillions of dollars into making fossil fuels and personal automobile transportation appear to be cheap-bordering-on-free, and we are continually robbing Peter to pay Paul. The reasons you can't just move to a city are that we've heavily restricted housing supply in the city, and tried to tie people down into homeownership with artificially-created long-term mortgages and expensive tax breaks for same... which has blown up prices.

          As far as 'massive concrete jungle' with modernist glass boxes and poor street life - that's a problem that's not endemic to the idea of cities, and which many cities around the world don't have. It's a problem Jane Jacobs devoted a book to half a century ago, and people have been speculating about at length ever since. I will leave you with this: Tons of Americans visit Paris or San Francisco or New Orleans or Georgetown and wonder why most American cities aren't built like that, why they can't have that kind of place for themselves. Mostly the reason is that American cities have been heavily redesigned and rebuilt for the purpose of expanding the use of automobiles, rather than for the inhabitants. Older pre-automobile cities with wide sidewalks, trees, and row-houses or low apartment buildings, with corner stores and other mixed uses? Even walkable small-town style development with a dense main street and then small lots on a grid pattern extending out from that? Americans tend to really like those these days. In the postwar building boom and for almost the entire time since, this sort of urban landscape has been very difficult to get financed and constructed.

          Value (economically) comes from trade. The more we are trading goods and services, the more value comes. I don't, personally, enjoy this part. I'm not the 'markets' guy at the table in policy. Nonetheless, it seems to be quite valid that an extra few percent of economic growth can provide a greater amenity to a population than a sizable array of programs to improve their living conditions through other means. In a currency union, value cannot be obfuscated or compensated by rates of exchange that inflate or deflate assets; the US dollar is the same everywhere. That means that if we were to stop the above social programs, the population of many rural areas of the country would quickly find themselves unable to feed and clothe and fuel themselves, experiencing a dollar shortage (see again: Greece's low productivity vs Germany's high productivity). I argue that keeping them afloat with subsidies should be carefully compared against simply providing aid to move their population to a city, where their children can actually live productive lives in a functional labor market. I argue that restrictions on growth in cities are economically and socially disastrous. I argue that carbon pricing is going to be an enormous drain on rural areas that so heavily depend on fossil fuels for every good and service they consume... and we might just as well skip the public panic about their crisis and pay them to demolish their houses and come live with us. It's probably cheaper for us in the long run. It helps the climate. And we make good sushi.

          1. Tyler Keniston | | #58

            This is an interesting, but also endlessly complex subject.
            Thanks for the picture you painted.

            I agree, in large part, with your analysis of the rural economic crisis.
            I think I differ on where I see possible solutions. I don't have the answers, but I also have skepticism that a massive relocation effort to large cities makes sense, for a multitude of reasons. That feels a bit like a 'throw your hands in the air' kind of solution. 'They should just come to US!' I can't fathom how that could even work, save for over quite long periods of time (likely generations).

            I have a feeling that our perspectives are inextricably linked with our own sense of place. Your use of language like 'come live with us...cheaper for us' and 'The only reason anybody still lives there' etc, indicates where your viewing station is (which is totally fair). The tone of your piece almost has me picturing your view of rural america as this sort of vast wasteland of tumbleweed and Walmarts, ripe with fat, lazy, and stupid welfare recipients. To be fair, I may indeed share a view of certain places as being 'other', far-away, and removed.

            In many ways I am actually arguing, like you, FOR cities. I am simply saying that we could consider having more of them at smaller scale, so that the rural expanses of the country develop their own centers of innovation. I don't view these 'centers' as isolated, and in-fact I think they need interconnections with each-other.

            It is generally felt that part of the issue in Maine is that people (specifically young, educated people) are leaving the state for the city. Yes, largely due to the opportunities of the city you speak of, but it also generates a self-fulfilling prophecy by reducing the base of educated work force. There is currently quite the labor shortage, which would seem to suggest that the work is here (and could probably grow) if people were willing to stick around.

            Obviously historical precedent can only be extrapolated so far in an ever changing world, but when we look to history at the ability of communities to self-sustain on far smaller scales than our nations megalopolises (with trade links to other communities of course), I can't help but feel we ought to be-able to work out solutions that can tie the modern economy successfully to smaller communities than said mega-cities. I fully realize the way these past communities survived will differ from how they would today.

            Ultimately, the case you've made for the economic success of cities doesn't feel unique to massive and sprawling environments. It simply speaks to the need for interconnectedness, education, and more intelligent economic models that integrate human and environmental needs.

            Many of the economic issues you raise (and tie directly to decaying rural communities) feel like issues with the economic model, not inherently the scale of living. While there are degrees of truth that non-city dwelling folks are being propped up on welfare and Walmarts, the top dogs of Walmarts, and other corporations, are getting unfathomably rich and keeping those funds, by and large, in pockets outside of these communities. It feels a bit backwards to say that the issue is the people on the sharp side of the stick and not the people with the handle. I'm aware that you weren't defending corporations so much as pointing out the ways communities are undone by them. But I can't help but feel like your solution seems to skip over the accountability part. Also, I can't speak accurately to the poverty and welfare issues of large cities, but a fair few of them seem to have significant problems in this regard (as you alluded to).

            It is worth mentioning, as an aside, that our outsourcing of resource extraction and production to other parts of the globe has simply put that aspect of our economy out of sight (and oftentimes mind). In this way, I question if the post-industrial economy of which your argument is based should not be reconsidered for the ways in which it embraces externalities and displaces adverse environmental and human impacts.

            Final note: developments in energy storage, transportation efficiency, and the internet based economy are seemingly rapid and likely to throw a wrench in the way we currently view economic opportunity. I do feel the argument for complete rural speckling of the landscape is weak, but I would think smaller city centers in regions of 'rural america' could do well with these changing parameters, if we're smart and intentional with our actions.

  11. User avater GBA Editor
    Martin Holladay | | #36

    There continues to be a lot of confusion over the meaning of "embodied carbon" -- with some builders assuming that the use of wood products for new construction must be good, because "the carbon is sequestered." That's not the case.

    In general, builders should, if possible, stop building, because new construction is associated with carbon releases. No one wants to hear this truth, so we often pat ourselves on the back for building timber-frame homes. I'm not sure we should do that.

    Would our forests be healthier -- and would carbon emissions be reduced -- if we left the large trees in the woods where they are, so that they can continue growing, instead of sending loggers to the woods with chainsaws to cut the trees down, removing the tops and allowing the tops and roots to rot, skidding the trees to a landing, trucking them to a sawmill, and sawing them into large timbers for an expensive timber frame? I suspect the answer is yes.

  12. Tyler Keniston | | #37

    I enjoy seeing disagreements among experts (I'm not being sarcastic) because it shows how complicated things are and hopefully humbles us all.

    The issue with larger timbers you raise, Martin, is an interesting one I've struggled with for awhile. My line of work is more related to land management than the production of housing.
    It seems the debate over wood as a building material hinges largely on timber management practices.
    One line of thought concerning the use of higher-quality wood is that if the demand is higher for larger and more mature trees, than forests will have economic incentive to be managed for such—as opposed to being managed for mow-down sized forests that are processed into chips for engineered products. This might require some patience and diversified investments on the part of large-scale timberland owners.

    Timber frame sized trees aside—for that seems a bit rife with uncertainty— I'm curious why wood products in general should not be considered sequestered carbon? The best case scenario, I agree, is to reduce demand altogether, and a tree left to grow in the forest is better than a tree cut down. The issue I see is that it becomes a matter of 'what do we use instead.'
    In other words, if we're inevitably going to build, if we don't use wood-products, are the alternatives actually better even if we consider the trees left in the forest.
    The other issue is, in today's economic environment, can we find incentive to protect forests in lieu of a 'working' status. I think the answer is becoming more and more 'yes', but probably not to the degree that a 'working' status can leverage.

    1. User avater GBA Editor
      Martin Holladay | | #38

      Tyler,
      Q. "I'm curious why wood products in general should not be considered sequestered carbon?"

      A. Almost all wood fiber used in residential construction eventually rots or burns, releasing the carbon into the atmosphere. At best, building homes with wood delays rather than avoids this carbon release.

      As you clearly understand, the issue isn't really whether preventing the rot of wood for 40 or 60 years is good -- the issue is whether the tree used to make the wood under discussion should ever have been cut.

      There are several other critical issues connected to this discussion -- the most important of which is the "front loading" problem inherent in any new construction occurring during the next 10 or 20 years -- critical years for the survival of many species on the planet. Even if a wood frame is "less bad" than CMU walls, new construction involves the manufacture of electric wiring, roofing, fasteners, flooring, appliances, and HVAC equipment -- and the manufacture of those items during the next decade is bad news for our planet.

  13. User avater
    Dana Dorsett | | #40

    >"Timber frame sized trees aside—for that seems a bit rife with uncertainty— I'm curious why wood products in general should not be considered sequestered carbon? The best case scenario, I agree, is to reduce demand altogether, and a tree left to grow in the forest is better than a tree cut down."

    Wood used in construction generally IS considered sequestered by most analysts' thinking, at least for the lifecycle of a house, which could be decades or centuries. Some insist that only documented sustainably harvested wood be considered sequestered wood (and not things like ipe decking culled from an Amazon forest before the rest was burned to make way for grazing.)

    That extends to cellulose insulation too- it's usually considered to have a negative carbon footprint despite the amount of energy used in the making of paper pulp due to the fact that it's reclaimed/recycled material that is being sequestered for the lifetime of the building.

    It's not always the case that a tree left to grow in the forest is better than a tree that is cut down. As trees become mature the growth rate and carbon-accumulation becomes much slower than adolescent trees. As long at the forest is being managed well, cutting down the mature trees and thinning the younger trees for optimal sunlight/growth can result in more (and more rapid) carbon sequestration, not less, as long as the mature trees being cut aren't used for fuel at sub-50% thermal efficiency. Cutting adolescent trees in their prime growth years to be turned in to 2x4s wouldn't necessarily be the best practice from a carbon management point of view.

    Trees are just one of the most-obvious carbon sequestration and atmospheric carbon reduction species, but more optimal management of GRASSES can have a bigger and more immediate sequestration effect, with most of the carbon ending up in the soil. Grasses go through a growth and carbon sequestration spurt when cut to some optimal level (which varies with species), rather than letting grow to hay-mowing (or longer) lengths. Some grass-fed beef ranchers are up to this level if management, rotating the grazing acreage to get optimal feed & carbon sequestration out of it, and argue that their beef is really net carbon negative, unlike the rest of the beef industry. I haven't checked their math, but the notion that most of the biological mass of not-irrigated grasses is usually below the surface.

    Most prairie grass species have roots extending 8-10' and beyond below the surface:

    https://www.nationalgeographic.com/photography/proof/2015/10/15/digging-deep-reveals-the-intricate-world-of-roots/

    1. Tyler Keniston | | #41

      Dana,
      I plan to look more into this grass subject (I recall you bringing it up before).

      I've recently been involved in discussions regarding managing fields for pollinators (i.e. bees). It would be interesting if a carbon sequestration model could be integrated alongside this objective. It seems prairie grasses are the focus of the topic, and I'm not sure how species native to New England compare.

      As far as trees... I completely agree that well managed can come out ahead of untouched, by many metrics. Mature trees will, after all, die and release their carbon from the forest as readily as from a rotting house. Of course, there are other considerations such as wildlife habitat, retaining seed and mother trees, returning carbon to soil, and intrinsic values. It's all about balance.
      In some ways we're talking ideals here; we just need to keep moving the needle towards thoughtful management of our resources and lands, in addition to reducing our demands altogether.

    2. User avater
      Michael Maines | | #44

      The best book I've read on the subject of what's happening in the soil is this: https://www.chelseagreen.com/product/the-holistic-orchard/. It's ostensibly about fruit orchards but the soil biome is the basis of beyond-organic farming and the author, Michael Phillips, goes into detail on the topic.

      I've been trying to find how studies that assume wood left to "rot" in the forest measure the release their carbon to the air. I believe that a lot of it is (or can be) taken up by fungi and redistributed to nearby trees, if the trees are selectively cut (or naturally culled) and the forest is allowed to remain healthy and intact, but I would like to see solid research either way.

      While I generally agree with Martin that timber-framing sized trees should be left standing to capture carbon, among other benefits, there are situations where they are best culled. I have a woodlot with a lot of eastern Hemlock (tsuga canadensis) of all ages, but many of them are at a mature size where their growth has slowed, their core becomes brittle and at least one big one falls in every wind event. Foresters say that within 10-30 years the wooly adelgid beetle will have killed them all, and climate researchers say that within 50 years our Maine climate will be too warm to support cold-climate species such as hemlock. (We are already losing hard maples and balsam firs as the climate warms.) So are those hemlock trees really better left to mature, or should they be cut and allow another species to grow? This is not a rhetorical question; I want a healthy, future-friendly forest, and wonder when (and if) the hemlocks should be harvested. If they are harvested, what is their highest and best use? Should a clear 30" hemlock be turned into 2x4s, large-dimension timbers where they can be seen and appreciated, or left on the forest floor?

      1. User avater GBA Editor
        Martin Holladay | | #45

        Michael,
        Your approach to forest management is admirable, and in the woods around my house, I try to apply the same logic you do. If I need to cut a tree, I try to select a tree that is near the end of its life, or needs to be removed for a reason other than my need for a saw log or firewood.

        That said, very few timber frames are produced from logs meeting the criteria you describe. Some are -- and my hat is off to the foresters and sawmills that think the way you do. The average owner-builder developing specifications for a retirement home, however, will probably find it difficult to purchase a timber frame from a forest managed like your woodlot.

      2. Tyler Keniston | | #46

        Michael,

        Hemlock groves are one of my favorite forests as far as the 'feel' of them. I feel like a gnome in them.

        In regards to Adelgid and Hemlock, these documents may be of interest: https://extension.unh.edu/resources/files/Resource005573_Rep7772.pdf
        https://masswoods.org/sites/masswoods.org/files/pdf-doc-ppt/HWA_Silvicultural%20Options.pdf

        A few points that seem relevant: It doesn't generally seem recommended to do a preemptive cut of uninfested forests in the name of the threat alone. I think the same applies to Ash concerning the ash borer. Some trees may prove resistant in both cases.
        If a cut is performed (for other reasons, or if it is infested), apparently doing so between August and February is best to avoid spread of the adelgid.

        The maturity of the trees might be seen as a separate factor, and may be reason to do some cutting. Forest management plans can be a good way to ensure a well-thought out, long-term strategy.
        The breadth and depth of these big picture management questions makes it hard to move forward with absolute certainty. Fortunately, doing nothing for a while isn't the worst thing in this case since the forest continues to grow without us.

        I recently installed b&b hemlock siding. Also used some as deck joists. We'll see how it holds up. As i'm sure you know, it is a bit prone to shake, and I think that becomes more common in maturity.

        I guess for me, I just want to be sure that if a preservationists mentality of forest management is taken, we aren't simply subscribing to NIMBYism and displacing our impact to other (often impoverished) regions of the planet. I'm not against trading of resources plentiful to specific regions, so long as environmental and economic burdens are not exported.

      3. Burninate | | #52

        At some point the naturalistic goals and the climate science goals diverge.

        Mature old-growth forest is a rare, treasured thing in ecology. It functions quite differently ecologically from an even-aged stand, especially a monoculture (a tree plantation). It usually has a much greater species diversity. The downside is it's hard to live in, because trees falling down and being left where they fall is hard for humans to accept. This is actively helpful, because many species flee human-inhabited areas.

        From a climate perspective, you want three things: You want to get carbon out of the air, you want to minimize any production of methane, and you don't want to spend a lot of carbon on the machinery to do whatever it is you choose to do. Monoculture tree plantations work fine for this. It doesn't matter what you do with the wood - you could turn it into charcoal and bury it (terra prieta), you could build a house with it, you could build furniture with it, whatever. You just need to not burn it, and you need to not let it rot. Rotting wood (and for that matter, rotting leaf & branch litter) emits some methane. Decomposer methanogenesis has a CO2 impact far higher (30 times more over 100 years, 80 times more over 20 years) than just burning the carbon. The exact biomechanics of how much methane is produced is a difficult thing to study. A mature forest probably emits much more of it than a rapidly growing forest, however. A mature forest has stopped adding to its living biomass - what carbon it fixes is deposited right back onto the forest floor and either emitted as CO2 by decomposers, emitted as methane by decomposers, or fixed medium-term in the soil in an inorganic form (negligible in most situations). https://hubbardbrook.org/online-book/forest-biomass-and-primary-productivity

        Mature forest is where big, expensive logs come from. Since cutting down nearly all of the mature old-growth forest outside of the PNW, we started building out of much smaller studs grown on lumber plantations. If you have uniquely large clear logs, the way to make the most money out of it is to cut, and use it for expensive furniture. Spend the money on solar panels or something.

        A compromise position is to thin a forest gradually, planting a mix of seedlings at a high stocking rate (if left undisturbed they would rapidly kill each other off), harvesting the smallest examples for firewood for the first couple decades, then for studs for a few decades, and then a mature phase where you harvest a little bit at a time for expensive furniture wood, with replacement planting of numerous seedlings spread out over the area. This at least slightly resembles the tree felling process that occurs in a mature wild forest, but with less methane and much more human benefit. The downside to this strategy is that it's labor-intensive, slow-payoff (which is a massive challenge when you could cut it all down now and ride the market), and a great deal of the logging infrastructure is optimized for clear-cuts, so not only may this be challenging economically, it might even be challenging in terms of how much CO2 you're emitting to cut & transport logs.

      4. User avater
        vap0rtranz | | #56

        Michael,

        A book isn't needed. American's love affair with turf lawns, pitted against prairie grass and other naturally occuring vegetation, and how soil naturally gets "made", has been studied many times over. Here's the one done with NASA that doesn't do the topic justic except that I did not know there were any incentives around for people to ditch turf grass lawn: https://www.huffpost.com/entry/lawn-largest-crop-america_n_55d0dc06e4b07addcb43435d

        But to get back to GBA: this is one reason I disagree with many folk's (including the infamous Joe Listurbek) giving LEED a bad rap. Sure it's imperfect but at least LEED for homes attempted to get at a more holistic view, like rainwater runoff, invasive species, etc., in addition to the house itself. PASSIV or whatever criteria Green building folks prefer should follow in LEED's footsteps, or improve on its holistic view, because it is in the homeowners perview to have a local, direct impact on the environment right in their front yards!

        Ornimental and horticultural varieties introduce by homeowners ARE often invasive and causing more problems for biomes. Kentuck bluegrass? Not native to anywhere in North American and is assisted by humans into becoming a monoculture species when planted as turf lawn. Burmuda grass: same thing, not native, outgrows natives when assisted by humans into become a monoculture, where monocultures are blockers to biodiversity and biodiversity is a sign of healthy biomes. The biome includes the natural "making" of soil, if that wasn't obvious; though what may be less obvious is that, in the context of invasive vs native species where some plants are not native and local, not all soils are made the same in a geographically defined biome.

        I'll admit that transitioning from a traditional American turf lawn to a more naturally diverse yard is tough. Your neighbors may stare more, and not in the envious "oh wow, I want THEIR yard" way :) Your home's "curb appeal" may take a hit. But I hope more GBA readers and commenters will take another look at their lawns, like the grasses that grow there, and make decisions for similar reasons that they made green decisions about their home.

  14. Darren Adams | | #42

    @ Martin & Dana: So, planning to relocate after retirement, I'm now wondering whether it is better to build my compact dream PassivHaus, or to buy and "fix" an existing ranch via gut deep energy retrofit to between Pretty Good and Passive levels, i.e. to the extent feasible. When I read the above, we should all just stay put and try not to consume, meaning don't build at all, just turn down the thermostat and ride a bike?

    Not being sarcastic, this is a serious question. I've pretty much decided that while I would like to, I can't afford to "fix" the stupidly large house we temporarily inhabit (work transfer) based on prior experience of an expensive energy retrofit on our last one despite fully knowing I would not recoup the (very large) investment. I understand "we" (all of us) would do better to first improve the current housing inventory rather than build a bleeding edge technology demonstration project, when considered from the perspective of the looming climate crisis. This will take some intentional investment: Time and Money.

    Recommendations? I'm guessing best would be to fix at least one small one, and if I still have the energy and cash then maybe one more for somebody else to live in?

    Willing to step up and do my part with the years left, but step in which direction .... ?

    1. User avater GBA Editor
      Martin Holladay | | #43

      Darren,
      The questions you raise are ones we all face in today's climate crisis -- and there are no clear answers. Your family's response to this crisis will be intensely personal and will blend issues of morality and politics -- so my own answers may not match yours.

      Many of us are struggling with the question of what combination of lifestyle changes ("don't build at all, just turn down the thermostat and ride a bike," as you put it) and political action (including, for some people, participation in voter registration drives, campaigning for political candidates, or nonviolent civil disobedience) are required at this unprecedented stage of human history.

      1. But Why? | | #47

        President Obama's deep moral conviction to addressing climate change led to him closing on a 7,000 square ft SECOND home in Martha's Vineyard

        1. Burninate | | #48

          ... And if the Republicans had permitted his policies to get anywhere, said home would be more than made up for.

          So?

          This "The advocates of not burning it all down must be paupers because they must be examples to us all before telling us what to do" and "Al Gore shouldn't be able to travel to make speeches on the climate because travel emits CO2. Checkmate liberals." positively reeks of "YOU'RE NOT THE BOSS OF ME YOU HYPOCRITE". Global climate is getting progressively more screwed up and you want to harp on the personal choices of the nouveau riche? As if that will help?

          But no. You don't want to help. You just want to troll. The climate presumably means nothing to you because the future means nothing to you. Like a child.

    2. Burninate | | #53

      If your house is stupidly large, maybe fix it up and turn it into a multifamily dwelling? If you open up the prospect that somebody paying rent might be factored into your financial payoff period, understand that it will also probably help the climate (depending on how urban your house is).

      My designs for plausible family housing are all stupidly large, because building a house to use less energy and last longer and be more accessible all supply incentive to add non-living space. "Don't put anything in the attic but insulation" say they - so I say "I guess I need some storage rooms". "Keep your ducts in a ventilated space" say they - So I say "I guess the mechanical room needs to be that much bigger". "Don't try to condition your garage" say they - so I say "I guess I need a workshop room". Thick walls and great sound insulation subtract from liveable space. A wheelchair-accessible first-floor bedroom (in a 'forever home') adds a huge amount to the footprint of both first and second floor. Using a "big shoebox" design is cheapest and hardest to screw up from an efficiency & moisture perspective, but it means that the second floor matches the first. The concrete, foam, and landscaping required to make a basement function versus the payoffs of using a basement are similarly daunting; Since the recent emphasis on embodied carbon even slab on grade is coming into question (with helical piers being the suggestion?). No attic bonus room (no dormers, vented attic) or above-garage room also expand the demands made of the first and second floor.

      If you want to project into the future - ask yourself "What would my financial choices look like with a $50/tonCO2 carbon tax?" Because that's what seems to be in the ballpark for even modest reductions in emissions: https://www.vox.com/energy-and-environment/2018/7/20/17584376/carbon-tax-congress-republicans-cost-economy

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