More Musings of an Energy Nerd
Builders and developers who claim that their homes are “green” have always been skirting with greenwashing. Here at GBA, we’ve certainly struggled with how to define green building. If we truly cared about the environmental impact of our shelters, we’d all be living in tents. Of course, most of us don’t want to do that.
Eleven years ago, in an article called “Who Deserves the Prize for the Greenest Home in the U.S.?”, I discussed the irony that many houses touted as green were either huge, expensive, or both. I quoted from several magazine articles claiming to have found the “greenest house in America”; these featured houses had an average size of 4,186 square feet and an average cost of $2.3 million. (A recent example of this type of article was published by the New York Times on May 7, 2023. The article, “A House that is as Green as it Gets,” describes a 7,477-square-foot house built on a $2.6 million lot in California.) The “greenest home” claims unintentionally pointed to the elephant in the room for the green movement: the fact that Americans consume a disproportionate share of the world’s resources.
The temptation to overinvest
American builders focusing on energy efficiency, high performance, or green features have been getting things wrong for years:
- In the 1980s and 1990s, builders got sidetracked by misguided obsessions with solar thermal technology, excessive south-facing glazing, and thermal mass.
- In the early 2000s, builders were sucked into a misguided focus on the Passivhaus standard.
- In the 2010s, many green builders were led astray by the fad for deep energy retrofits—a type of retrofit that was never cost-effective.
- These days, most green builders are led astray by focusing on operating energy costs rather than embodied energy and embodied carbon emissions.
The common thread linking…
Weekly Newsletter
Get building science and energy efficiency advice, plus special offers, in your inbox.
This article is only available to GBA Prime Members
Sign up for a free trial and get instant access to this article as well as GBA’s complete library of premium articles and construction details.
Start Free TrialAlready a member? Log in
47 Comments
It's always a pleasure to read Martin's blog posts.
E. F. Schumacher, "Small is Beautiful" (1973)
Good ideas have been around for a long time. We don't lack for very good solutions.
What a great article with intelligent and sage advice that is, sadly, difficult for so many of us to follow since most of us love to build and create. But you are totally correct that doing less, making less, spending less is best..... I think of the villages in rural Africa where my group (Kageno.org) works. The carbon footprint of the entire village is not much more than that of a large American family. Most of their materials are sourced locally and what they do import, is done frugally and carefully.
Several points to add to your piece: first, now that interest rates have increased, the lifetime cost of many capital intensive projects like deep energy retrofits have increased dramatically thereby making the economic calculation harder to justify. I often see people fail to calculate these costs of capital into their analysis of break even points on a project. Higher costs of capital auger for smaller, simpler structures and solutions.
Second, I would add to your list of things to do if you have to build: "use less masonry and steel wherever possible" . We have been building on wood pilings at the Jersey shore for 75 years and it works fine. Pole buildings in farm communities have been around even longer. And slab on grade is better than a full basement.
Please check out Skylar Swinford's article available at the Passive House Accelerator below. He does a deep dive into the embodied or upfront emissions due to thicker walls, triple pane windows and increased enclosure materials of Passive Building vs. the operational energy savings. He has created a open source tool called the 'Operational Carbon Embodied Carbon' (OCEC) tool. What he is finding is that if one zooms out to include the regional grid emissions and the reduced mechanical systems, specifically reduced amounts refrigeration the payback for the upfront carbon emissions is 'paid back' in a few years-- even with his example of an 'all foam' Passive building.
Of course, this isn't an 'either or' scenario and most thoughtful folks are combining low upfront carbon materials, often vetting them with the BEAM calculator and doing 'both and' operational savings of Passive or Pretty Good House level enclosures. Also, the Phius standard has been reducing its enclosure standards with each iteration based upon the source energy factor of the U.S. grid. As the grid gets cleaner and cleaner, the source energy multiplier goes down and the enclosure requirements go down, too. One should endeavor to set one's enclosure robustness with upfront carbon emissions and operational carbon emissions with a baseline of providing durability, health for occupants, resilience and comfort. This is the intersection to aim for.
Of course, your point of building smaller still stands. This should still be the first consideration.
https://passivehouseaccelerator.com/articles/new-tools-for-assessing-upfront-and-operational-emissions-no-passive-house-emissions-backfire-found
This is an excellent point. If you are coal powered, you are at 1kg CO2/kwh consumed. Natural gas around 0.5 kg/kwh. Hydro/Nuclear/Wind/Solar are estimated at 0.05kg/kwh. If you look at the BEAM estimator article, they show the Go Logic house requiring 26,000 kg CO2 to construct.
For a hypothetical scenario - my HDD here in Zone 5 are around 6000 with a design temp of 5*. Say I have a 2,000 sqft house with a heat load of 48,000 btu. Per year, you are at around 10,000kg CO2 for coal + Heat Pump, 6500kg CO2 for a 90% furnace, and 5,000 kg CO2 for natural gas + heat pump. Change your heat source to Coal + Resistance heat and you can watch the glaciers melt in real time... 30,000 kg/year. This is napkin math, but gives a rough idea of the numbers.
I used to be a part of a traveling lab that taught Hybrid/electric vehicle courses to industry professionals. We operated out of the upper peninsula of Michigan. The drive was 550 miles to Detroit where most classes took place. We counted the amount of CO2 we produced on a trip once (2 semi trucks and a Tahoe) and were a bit surprised to say the least. 5,000 kg CO2 just to go teach people about how to design vehicles that produce less CO2.
Tim, your anecdote about driving vast distances to attend a meeting speaks to the other elephant in the room: that nobody can build anything green enough to overcome the consequences of urban planning or business policy.
During the pandemic I worked on a commercial construction project where the customer built a campus with green and employee-friendly amenities like micro kitchens, shuttles, bike lanes, and a park with a lake.
Even with a 2-day hybrid work schedule, that campus will induce the carbon costs of over 300,000 commutes every year for 3000+ employees, to say nothing of the carbon costs the county will incur to maintain the infrastructure serving this place.
I remember thinking to myself as I drove the 120 mile commute how the project design was unintentionally converging on a land-use paradigm COVID-19 finally made obvious to everyone: that the greenest, most employee-friendly office building in the world is an apartment block with decent internet.
I'm so sorry you had to drive so far to go to work!
Martin, if your concern is reducing carbon emissions in the near term, advising your readers to take their eye off operational emissions is bad advice. I believe you may have been misled by upfront carbon evangelists that incorrectly assume nearly zero carbon electricity in their operational emissions calculations.
I hope you will consider this very basic example below to bring some context to the matter. I've also attached a few graphs from a recent article I co-authored with Zack Semke on this topic. A link was provided to the article by an earlier comment, but I will link to it again:
https://passivehouseaccelerator.com/articles/new-tools-for-assessing-upfront-and-operational-emissions-no-passive-house-emissions-backfire-found
I would not so quickly dismiss the near term benefits of reducing operational emissions. An efficient home with more upfront carbon invested into the building enclosure can indeed have lower emissions over the next 10 years (even next year) than a less efficient code home with lower upfront enclosure emissions.
Below is a simple emissions comparison of a hypothetical all electric 2,000 sf home with an EUI of 30 vs. 15. This example assumes a project in 'low emission' Washington State.
The ASHRAE 189.1 Emissions Factors for the NWPP subregion is 0.936 lb/kWh (Based on EPA eGRID values w/ upstream emissions and transmission losses included).
Below are the projected operational emission values for the hypothetical 2,000 sf home for a single year using the ASHRAE 189.1 emissions factor:
Annual Emissions
EUI 30: 16,460 lbs CO2e/yr
EUI 15: 8,260 lbs CO2e/yr.
For some context, wrapping this entire home with 4" EPS would add <10,000 lbs CO2e based on values from the BEAM Estimator. Using low embodied insulation material rather than EPS could reduce this upfront embodied carbon by 10x. Upgrading to triple-pane glass would add <1,000 lbs of upfront CO2e emissions.
In reality, the grid is decarbonizing, and these emission factors will steadily improve in the future.
In 2021 NREL calculated Long-Run Marginal CO2e Emissions Rates for Washington State using their forward-looking emissions tool, Cambium, which projects future decarbonization of the grid and increasing load growth from electrification over a 20 year time horizon starting in 2024.
Based on the analysis from NREL, Washington State has proposed a statewide carbon emissions factor of 0.44 lb CO2e/kWh. This emission factor is averaged out over 20 years, so emissions in years 0-10 will be much higher than years 10-20. Efficiency decisions today and tomorrow do matter.
Below are the projected operational emission values for the hypothetical 2,000 sf home over a 20-year horizon with the 0.44 lb CO2e/kWh emission factor for Washington State:
20 Year Emissions (LRMER)
EUI 30: 154,748 lbs CO2e
EUI 15: 77,374 60 lbs CO2e
Even in 'clean' Washington state the operational emissions over 20 years could be nearly 40 tons less over the next 20 years with a low energy building.
Some more musings to consider.
Imagine if the less efficient home with an EUI of 30 had a 3 ton heat pump with 12 lbs of R410a refrigerant and the energy efficient home with an EUI of 15 had a 1 ton heat pump with 4 lbs of refrigerant.
R410a has a GWP20 of 4,340 and GWP100 of 2,088.
If the heat pump were to lose all of it's refrigerant charge over its lifespan below are the equivalent emissions:
3 Ton Heat Pump: 52,080 lbs CO2e GWP20, 25,056 lbs CO2e GWP100
1 Ton Heat Pump: 17,360 lbs CO2e GWP20, 8,352 lbs CO2e GWP100
The reduced peak loads and smaller heat pumps gained from a high-performance enclosure shouldn't be overlooked in the current era of high GWP refrigerants. There are also benefits to reducing future winter peaks on the grid to be considered.
I think you are correct to encourage building smaller. We should certainly focus on using lower emissions materials in construction, but we shouldn't ignore or discount the operational carbon reductions and lower peak loads that investing in improved building enclosures can provide in the near term.
To User 7833485 and Skylar Swinford,
I'm grateful for your calculations using the BEAM Estimator. I haven't yet had a chance to use that tool yet, and I don't pretend to be fully versed in the tool.
That said, I know that Michael Maines has pointed out that the BEAM Estimator "is not comprehensive--for example, they said there is little to no solid data on embodied carbon of things like plumbing fixtures and electrical wires. They could have used estimates or approximations but decided to stick with the things they have reliable data for, so you won't get a true accounting of the carbon impact of the entire house."
I assume that this means that there are more carbon emissions associated with materials purchased to build a new house than the BEAM Estmator captures. I also understand that it doesn't estimate transportation energy needed to get builders to the job site.
In any case, if any GBA readers are tempted to build a new Passive House-compliant residence, one of the first questions I'd ask is, "How much does it cost?" If it costs $300,000 or $400,000 -- and frankly, I suspect it costs $800,000 -- then my next question to anyone concerned with a "green" lifestyle is, "Is there somewhere else you might be able to live that won't cost you as much to buy? Perhaps a trailer?"
I know that triple-glazed windows don't make sense in Massachusetts from a cost-effectiveness point of view -- a PV array is a much better investment. And if you want to reduce your home's carbon footprint, it's hard to beat the old standbys: A PV array on the roof and a minisplit in the living room (along with inexpensive air sealing, of course). But if triple-glazed windows make sense from a carbon reduction standpoint in the Pacific Northwest, I'm surprised -- especially considering the fact that the more expensive windows need to be purchased now, when our atmosphere is ailing, and they are being manufactured at a time when none of us should be visiting a lumberyard unless we have a very strong reason to do so.
That said, I'm willing to eat crow if some of my statements don't hold water.
Martin,
(This is Josh Salinger-- my account is on the fritz)
I don't care to watch you eat crow! Rather I'd be advocating for a conversation over a balanced diet that includes some vegetables ;)
It seems you are missing the point on upfront and operational carbon per Skylar's argument. I agree that building smaller or not building at all is the first best way to address the climate crisis via the built environment. One can't argue that. But the energy transition is going to take a lot of building, not to mention that here on the west coast there is an affordable housing crisis that will require even more building. This is 'Green Building Advisor' and not 'Green Not Building Advisor' after all. With the building that needs to be done, we need to be clear eyed about how we go about it.
If you look at his argument, he is essentially showing that if one installs a mini split and PV on a code built home one is emitting more carbon over a few years time by trying to emit less upfront carbon via the enclosure choices. It will take some upfront carbon to get to the goal of a decarbonized economy. By investing smartly (bio based insulation, wood framing, etc. etc.) in more robust enclosures (even *gasp* triple pane windows when appropriate) the positive effects on carbon reduction move beyond just a single home and a short timeframe and can address problems such as peak loads on the grid and resiliency in the face of more frequent disasters, to name a few. Yes, more robust assemblies cost more money and potentially emit more carbon (depending on specific materials choices). This upfront carbon investment is a fraction of our remaining carbon budget and will pay back multiple times over as this investment does its part of the heavy lift as we transition to a cleaner and cleaner grid. Either we are going to pay for it, or we are going to pay for it. May as well pay for it now when it will cost less.
I will agree that if the grid was completely carbon free then we could set our enclosure targets to hit durability, health, resilience and comfort targets and potentially large swaths of the country may not need triple pane windows to meet these goals. I would argue that code isn't hitting all of these aforementioned goals at the moment (robust air tightness standards? balanced ventilation?). The grid isn't clean at the moment, either. Using more energy from our current grid now by just installing heat pumps and PV on code level homes will emit more carbon in a few years time due to more refrigerants and energy usage than the extra carbon needed for more robust enclosures. I agree that we need to address carbon now. We need to do it with low carbon building materials, smaller homes, leveraging the existing built environment and when we do build new- do it smaller and with more robust enclosures. It's a both and scenario.
J
Also, I re-read your critique of Passive Building from 2011. FWIW, the Phius standard anyways has addressed most of your demerits and may be worth revisiting.
Martin, while you quoted me correctly, I wish I had phrased my comment differently because it makes it sound like I don't think the BEAM estimator is valuable, which is incorrect.
No carbon-accounting tool available today can accurately calculate the full carbon impact of our buildings. Some use estimates for the highly variable emission categories but the developers of the BEAM estimator decided to focus on the categories and materials that we have solid, reasonably consistent data for. The BEAM estimator is excellent for comparing the things that we have the most control over. Most of the things that don't have accurate data are things that don't change significantly between most "green" homes and conventional homes, such as Romex wiring or Kohler plumbing fixtures.
Michael,
Thanks for your comment. I certainly had no intention of misrepresenting your position, so your clarification is important.
That said, the contention that it may be possible to build a new building that draws more carbon from the sky than it emits depends precisely on the math that we are, at this point, unable to do. So the issue remains an important one.
Martin, I agree that it's important to be able to measure all of the carbon that we use in buildings--IF the goal is to be net carbon positive. Until we can calculate that accurately, the BEAM estimator is still very helpful for doing the best we reasonably can. While being a building designer is a tough gig for an environmentalist, and I talk people out of doing projects regularly, people still seem to want homes and renovations and I don't see that changing anytime soon.
Im really struggling with the notion that above-code buildings allow smaller heat pumps to the extent that refrigerant accounting in its overall environmental footprint makes sense based on the size of the heat pump!
Holy cow! If that is true-- if small differences in the amount of system refridgerant has that much of an impact on the total buildings CO2e impact--surely that suggests using refrigerant based systems AT ALL is a bad move.
maine_tyler,
Some refrigerants in use today have extremely high gwp, often 2,000x that of CO2 (although the Kigali agreement is phasing these down). In some developing countries, only 10% of the refrigerant is recaptured after an appliance's end life. Here in the U.S. it is 70%, but even the 30% is nothing to sneeze at. Couple that with the fact that mini split and VRF systems use a lot of refrigerant it is a serious concern.
The refrigerant issue is part of the problem here, the other is that our current grid isn't clean. When those two things are coupled together, operational emissions right now, really matter in the short term. Again, this is a both/and scenario where we need to address upfront emissions with low carbon enclosures and smaller buildings.
Heat pumps are a good thing. Refrigerants are getting better. Heat pumps can be designed to use less refrigerant. Some heat pumps use CO2 as a refrigerant. Using packaged heat pumps or air to water systems reduces refrigerant use. Distribution via forced air can reduce refrigerants if the system is designed so the indoor and outdoor units are close together.
I worry that the opposition will latch onto this refrigerant issue and it will become the new birds in windmills talking point. I don't think we need to go full Henny Penny on refrigerants, but we do need to be strategic and smart about them.
Josh,
Thanks for the explanation.
It's not that I don't understand the large CO2e of refrigerants, but it's hard for me to intuit that downsizing a heat pump system (by virtue of above-code envelopes) would have as drastic effect as suggested (refrigerant recovery wise) in terms of a building's GWP over mid-range time spans. IF the arithmetic shows that to be true, than surely the same arithmetic would suggest that refrigerants are just so darn awful that we ought not to use them at all?
In other words, I have a hard time squaring those two sentiments; seeing them BOTH as being true. But perhaps it is simply that my intuition fails and the arithmetic truly does bear out both statements as being true...
Obviously the arithmetic depends heavily on many compounding factors, like 'how did the building surpass code' (wood based insulation, spray foam, etc.?) and how dirty is the grid, etc.
>"But the energy transition is going to take a lot of building, not to mention that here on the west coast there is an affordable housing crisis that will require even more building. "
I agree completely. East coast too.
Yeah, it isn't intuitive. This is where the data Skylar has crunched can provide the clarity. He did a nice webinar that was recorded at the Passive House Accelerator that is an easy to digest way to take in the numbers.
Of course we are at the leading edge of this thinking and more info, data or a casting of a wider net may lead to different results. That being said, my thinking is currently swayed by his work and endeavoring towards low carbon enclosures, low operational energy and reduced and better refrigerants seems to be pointing in the right direction...
Yes, but... I have been building cheaply for decades and used to hide the fact with euphemisms, such as workforce housing, achievable and cost-effective. Nowadays, I say cheap. I'm proud of it. Having lived in the third world, I know that poorer people and a cheaper lifestyle reduce your environmental impact by magnitudes--and your stress levels, too. Spending a lot of money pretending you're doing good when you're just indulgent is stressful. In the USA, you cannot just ride a bike. You must ride a special bike with a titanium frame and disc breaks and wear a stylish helmet, racing tights, a windbreaker--and a serious expression. It's all competition. I am greener than you. When I was accused of saddling my buyers with high fuel bills, I asked the utility company to see if it were so. It was not; the utility bills on my little, highly affordable, cheaply-built, vinyl-clad houses were among the lowest in the city. There is a reason BEES is building for environmental and ECONOMIC sustainability. Money is a measure of energy. Learn to spend less, and you will greatly reduce your carbon footprint. Thank you for such a clear and cogent expression, Martin. And for illustrating the article with some of the most cost-effective homes on the market, manufactured units.
The local green home tour coming up has one straw bale home built for $300k (in the good old days before the pandemic) that follows these principles, but all the other homes are over $1.3 million and a few over 5000sqft. I just don't see what's 'green' about that. Sure, the operating costs are probably less than comparable mansions, but they're also probably higher than my 900sqft millworker house from the 40's. It's a tough battle, as the builders putting in the extra effort want to get paid for it.
I think the principles valued on this site just need to become more common, as most of them are not inherently difficult and don't require expensive materials. Once PGH type methods are ordinary, maybe the premiums charged will drop. The public needs to demand it.
Stirring the pot Martin!
I think there are (at least) two approaches that can be separated:
1) The environmental* cost benefit analysis of any given action (building a certain way)
2) How to best spend ones resources to combat climate change.
*It's REALLY important for number 1 not to use simple economic payback, because that can be extremely off for a variety of reasons (externalities).
In case 1, it's basically, 'how long of a payback for a given choice'. And, 'what is an acceptable payback period?' This can of course get quite complicated when we consider the systems approaches, such as how the current and future energy grid will interact with the thing we are building.
Case 2 is indirectly concerned with externalities, but the primary analysis is economic. It asks how we should devote resources to 'reducing' our climate impact (or 'improving' the situation). Is devoting those dollars to triple pane windows as environmentally worthwhile as buying your neighbor a used EV (as a random example).
I'm not convinced case 1 would lead one to the conclusion of this article (as other commenters have pointed out), but I think case 2 might.
If you forgo triple pane windows because it 'doesn't pay back quickly enough' but then upgrade your stove with the savings, you've made negative progress!
Where should we, as a society, devote resources to on this issue? And unless the answer happens to be 'in well-to-do people's homes', we need to find a way to redirect capital so it can get to those places. Gasp! socialism! Put an American bullet in it now.
Maine Tyler,
Well stated. Thanks for your comments.
You wrote, "I'm not convinced Case 1 would lead one to the conclusion of this article." Let me state Case 1 in simple terms: Code-minimum levels of insulation (and code -minimum specifications for windows and other envelope details) are set, more or less, as the consensus level of reasonable investment for new homes, based on the economic payback of these features' performance over the next few decades. True, this is based on economic rather than environmental payback, but in almost all cases, improving these specifications entails increased carbon releases for manufacturing more expensive materials than the code-minimum materials.
What matters for our planet is whether we are going to make it through the next 15 or 20 years without an environmental catastrophe. If, through some miracle, our planet's inhabitants reduce our carbon emissions enough in the next 15 or 20 years to avert a catastrophe, it will be because of a massive effort to decarbonize the grid. If we succeed in that decarbonization effort, we'll be able to breathe a little easier, and (perhaps) start building our homes with thicker insulation and quadruple-pane windows, because our factories will, at that point, be powered by wind turbines and PV arrays.
But the real trick is getting through the next 15 or 20 years.
Martin,
I guess the question that keeps coming up for me is whether it makes any difference? Would an unprecedented collective change in building practices in North America towards less consumption, appreciably affect global carbon emissions?
That is of course a separate question from whether morally we have an individual obligation to act whether it makes a difference or not?
Malcolm,
Your question may be pertinent, but I'm not particularly interested in the answer. My main point is that most new American homes -- including (and perhaps especially) homes with above-code levels of insulation and triple-glazed windows -- shouldn't be called "green."
Fair enough. Philosophically I tend to be a consequentialist, so it still leaves me wondering: If what we do collectively as builders doesn't make a difference to whether there will be enough changes in the next 20 years to combat climate change, who cares which houses are green and which aren't?
Malcolm,
I suspect that all of us, even on our death beds, will have no idea whether our actions made a difference. Yet each of us, every day, makes choices. This is the universe we were born into. The only life you get to lead is your own.
"I guess the question that keeps coming up for me is whether it makes any difference? "
Doing the right thing is always the right thing to do, regardless of whether it makes a difference. We also need to keep in mind that there may be other more important things we (or others) need to do. But even our small efforts contribute to the solution. In fact, though we need to do the big things, our small efforts may be what put us just over line to success. Also, there's "moral authority". If we don't do what we can, we have fewer tools to pressure others to do what they can.
Malcolm,
Are there other actions you have in mind that would be more consequential (or some examples of possible actions)?
While there are of course actions that may carry more weight than other actions, in the end, it is the sum of many small actions that constitutes the whole.
I'm not sure you are suggesting this, but your type of question seems to be the type that can lead certain peoples to conclude that no action is worthwhile because there's always someone else somewhere else doing something bad.
The classic example is when people say North Americans have no responsibility to act because, China...
Meanwhile, China is probably thinking, "we have no responsibility to act because 'the west' has been at this game for decades before we even arrived, and are just waiting for us to make sacrifices (oh the arrogance!)."
It's a game of chicken but everyone is a loser simply by playing the game.
I actually don't think this issue has anything to do with a sort of moral responsibility. It's simple math.
5 x 1 billion is 5 billion. 5 is a tiny fraction of 5 billion (inconsequential we might conclude) but if the 1 billion is a set number, our leverage point is to have the 5 become smaller.
maine_tyler,
No. I'm not disputing Martin's correct assertion that "green" should be reserved for low impact interventions. My question is quite narrow: Will these actions appreciably aid in reducing climate change in the short term?
Just like any other project involving the physical world, I think we need to be clear-eyed about what the aims are and whether what we do is going to achieve them. Helping build a small dam to protect a village, when there is a large dam upstream about to burst and overwhelm the whole valley is pointless. And I don't agree with Jollygreenshortguy's assertion that we are morally obliged to take actions we know have no chance of success just to stake out the high moral ground.
There are countless good reasons to to do what Martin is suggesting - there always have been. I don't think expensive boutique green projects have ever made any sense (nor can I remember Martin ever advocating for them). My point is simply that if you are going to hang the justification for living a certain way on combatting climate change, it needs to be effective, or it is pointless.
Malcolm,
Of course we all wrestle with the question you raised (even though I told you that I'm not particularly interested in the answer). I'll rephrase your question, however, and provide a few thoughts: To what extent is humankind's response to the climate change crisis necessarily a governmental response rather than an individual response? We definitely need system changes -- changes in taxation, changes in electrical generation, and changes in transportation options -- that are hard for individuals to effect.
It can even be argued that powerful and wealthy people who profit from fossil fuel burning are happy to see individuals dither and argue about lifestyle choices -- because it distracts us from engaging in political and economic revolution. The powers that be want to avoid mobs with pitchforks.
Martin,
I agree entirely - and I think that answers Maine-Tyler's point about what other actions would be more consequential.
It reminds me of an interview with Noam Chomsky some decades ago when he was asked what the consequences of deciding not taking part in the consumption that is inherent to living in Western Capitalist economies. He answered that from their perspective, you simply don't exist. You are dead.
Malcolm,
>"Will these actions appreciably aid in reducing climate change in the short term?"
I'm not entirely sure what will. Certainly building new code min houses is not 'aiding' in the fight against climate change at all. It's (at Martin's suggestion) *less bad* than building fancy passive houses, of which those fancy passive houses are *less bad* than extravagant energy hog mansions.
>"if you are going to hang the justification for living a certain way on combatting climate change, it needs to be effective, or it is pointless."
True... but how we determine was is 'effective' depends a bit on how we parcelize the analysis. If by effective we mean that humanity has collectively reduced total emissions by some action, than nothing anyone has ever done has been effective because we have never reduced emissions vs raised them from one year to the next. I believe Covid's economic slow-down maybe had a noticeable turn-down for a short time. Basically anytime the economy tanks, emissions go down a bit.
If we instead parcelize to the building industry, then we should ask what has allowed that industry alone to reduce it's overall emissions (even if there hasn't actually been a net reduction). And in that light, enacting energy code that everyone adopts is certainly more effective than relying on consumers to make personal choices-- especially given that energy costs are subsidized by the environment.
We could further parcelize and start to see 'improvements' at certain scales, even if those small scaled improvements seem trivial.
I take your point (and agree) that there are levers that will have much more prominent trickle down effects than every individual making individual decisions. E.g. when the Montreal Protocol was enacted we saw real improvement of the Ozone depletion. Unfortunately, I'm not sure there is an equivalent step to take in this case given the scope of the problem.
"Code-minimum levels of insulation (and code -minimum specifications for windows and other envelope details) are set, more or less, as the consensus level of reasonable investment for new homes, based on the economic payback of these features' performance over the next few decades."
Assuming that is true, I would add that building to 'code specs' doesn't always dictate the materials or methods used to achieve compliance (to make an obvious statement).
In other words, one could likely build an above code house with LESS embodied carbon than a code min house based on materials and methods, not to mention local specifics like site location and supply chains. Perhaps not common, but possible.
Code also says nothing of structure type or size, or whether the occupants will need to commute 60 miles to work everyday (an 'operational' trait that could very quickly dwarf embodied traits). Obviously you know these things and have made points to the same effect; I'm just suggesting that perhaps what defines a build as 'green' or not has less to do with code and more to do with a host of other specifics. And maybe that's part of your point.
Insofar as we are comparing apples to apples (which is likely your intent), such as identical sites and materials choices, I can see the argument even in 'case 1' perhaps being true. Though I think there are many compounding variables that makes it tough to pin down as a blanket statement. I suspect that at least a few 'above-code' actions have respectable paybacks-- particularly the actions that don't cost a lot more to begin with, or actions that primarily add labor as opposed to highly processed materials.
Maine Tyler,
You wrote, "I suspect that at least a few 'above-code' actions have respectable paybacks."
I agree. One example would be to increase the thickness of the walls on a straw-bale house from an orientation that results in code-minimum R-value to a different orientation that results in above-code R-value. (Assuming, of course, that the amount of fossil fuel used to bale the straw and deliver the straw to the job site was not egregiously large. You get extra points if you live near a farmer who bales his straw, and if you can hire an Amish farmer to deliver the bales to your job site with a horse and cart.)
I agree with many of your other points as well. We probably agree on the following: it's better to rent an apartment in an old house near public transportation than to build a new house. If you must build a new house, build it close to public transportation, choose materials with low levels of embodied carbon emissions, and make the house as small and simple as possible.
Bud Barta,
Being an organic/sustainable farmer since the 1980s and an environmentally aware builder for the same time - I have an awareness that may be uncommon.
The top meter of the world’s soil contains three times as much carbon as the entire atmosphere.
Through photosynthesis plants absorb CO2 from the atmosphere – this carbon returns to the ground through decaying organic matter. This sequestered carbon becomes stable over time.
Agriculture is a process of mining the soil. Nutrients including carbon are removed – this process depletes the soil of nutrients - reducing the organic matter – thereby reducing the capacity to grow crops without the use of unsustainable chemicals and fertilizers. The more organic matter harvested off the soil - the more it is depleted. By depleting the organic matter in the soil - agriculture is contributing carbon to the atmosphere – making agriculture one of the largest contributors to climate warming.
If we further reduce the organic matter by removing (Waste?) and (sequestering?) it in buildings – we are contributing more carbon to the atmosphere than if we leave it in the soil. In other words – there is no such thing as agricultural waste – As much organic matter as possible should be restored to the soil.
The higher the organic matter in the soil - the more nutrients are available for future crops. The higher the organic matter in the soil - the higher the water holding capacity of the soil – so water will not run off but will remain in the soil to support future crops. The more organic matter in the soil - the more fertile the soil – the more crops can be grown with fewer inputs. – thereby generating more abundant and more nutritious crops.
Don't think that sequestering carbon in a straw bale building is helping the planet. Removing straw from the land to build “green “is not “green”.
It has been a challenge for me to build “green”, Though I have built straw bale houses – I have been disappointed in the carbon footprint – especially if you consider the above argument.
As I contemplate the Eco-friendly options – Building with reclaimed materials and earth/dirt -is as good as it gets.
Using reclaimed material can be quite attractive - for years I have been trimming and sometimes siding my projects with reclaimed materials. Sometimes we use reclaimed materials structurally. We have even taken down and re-stacked old log houses .
We have used 4ft deep washed gravel foundations to reduce the use of concrete. After 20+ years - still no cracks in the wall board.
As this article so clearly points out - often times - what we think of as green may not be green at all.
Thank you for such a great article - along with all the following discussions.
Budb,
Fascinating and important perspective. Your points about soil carbon are important, though I question your conclusion that no residue should be removed in order to maximize soil carbon uptake and structuring.
This is a complex topic worthy of several books. I wonder though if improving soil carbon doesn't require every last unit of above ground crop (including trees here) to decayback into the soil. More carbon is sequestered during growth via rooting than by decaying slash and chaff.
I'm not saying there aren't benefits to leaving debris as there definitely is. But I wonder if when we consider leakage (thre idea that if we don't take from one place, we take from another. I.e. we build with steel and concrete instead?) makes the equation a bit more complex and would allow for some removal of biomass. But yes, soil structure and ecosystem carbon sequestration should still be priority! But those things needn't be entirely compromised by (smart) removal of some biomass.
At least that's my current thinking.
Response to #23: The carbon in plant residue comes mostly from the air, not the soil. Sequestering it in buildings leads to MORE CO2 being pulled from the air, it does not add CO2 to the air.
I've always been a bit leery about claims that biomass based building products are somehow carbon 'positive' (not that you are explicitly making that claim).
For at least 2 reasons:
1) we still expend energy/carbon to extract and process the biomass into something useful, and
2) because of the net effect on the soil/ecosystem sequestration and storage capacity.
It's true that most of the carbon is sequestered from the air, but the capacity of the soil / ecosystem to sequester and store carbon can be affected by extractive processes. It's the drawdown of the other nutrients besides carbon and the lack of soil structure that can negatively affect future carbon sequestration and storage. In the case of really heavy logging cuts, an extreme example of this is physical loss of soil due to erosion and compaction. Less extreme examples are when nutrient rich components (like branch tips) are removed, or increased heating of soils from solar exposure, which can release carbon.
This doesn't mean removing above ground biomass inevitably leads to an unproductive ecosystem/carbon sequestration mechanism, but it is part of the equation that may affect the 'caron positivity' of storing these materials as durable goods in buildings. The *use* of the goods and the *production* of the goods are two sides of the coin, and the *production* side of biomass products doesn't get as much air-time in the building community.
If the notion that we could store biomass in buildings and come out carbon positive were true, than it seems the logical conclusion is that we should simply harvest as much biomass as possible from everywhere and put a roof over it.
This isn't to argue that wood and biomass building materials are worse than things like steel and concrete; only that they probably (most of the time) shouldn't be considered carbon 'positive.' I saw that claim in the recent "Do Deep Energy Retrofits Make Sense" article: the author claimed use of cellulose actually off-set use of foam. That's some sketchy logic imo.
To take this a bit further into the weeds:
Oil could also be considered a form of carbon in likeness to a tree in that if both get turned into a durable good, both are storing carbon. AND both were storing carbon before we came along and repurposed it.
Which implies that the main difference between the two (other than upfront carbon investments to extract and process the goods) is that one is pulled from an active growing/carbon cycle, whereas the other is pulled from dormancy. So it is apparent that the effect we have on the growing/carbon cycle of an ecosystem by any interaction or extractive process should be of utmost concern.
And it's complex. One notion is that younger regenerating forests sequester carbon more quickly than older more mature forests. Which favors the extraction of trees. However further readings suggests that this may be an overly simplistic analysis and that the carbon budget is dominated by below-ground portions (e.g. soil, root mass, and mycorrhizae) as well as how much site disturbance occurred. I have even seen claims that some cuts release significant carbon for many years post harvest. It's not something that is easy to generalize or summarize, but generally, careful entries into the forest are better than careless ones.
" it does not add co2 to the air." This is true - Plants absorb co2 from the air and the soil. So - you rob carbon from the soil and from the air, then incorporate it into a building - this seams like positive carbon sequestration. Removing the organic material however will diminish the carbon content of the soil and can result in negative impact on soil health and on the physical, chemical and biological properties of the soil. Also for example wheat straw contains a moderate amount of nitrogen and potassium. What is the cost to replace that with the synthetic alternative.
Again I want to suggest we include the amplifying effects of building organic mater in the soil and the cost of replacing the mined nutrition with synthetic nutrition - when we consider our options.
It is not as simple of an argument as one might expect.
I would be interested in reading more about how much CO2 for plant growth comes from the soil vs the atmosphere--do you know of any sources?
As an organic farmer, you know that nitrogen is also available in great supply from the air; all you need are nitrogen-fixing bacteria such as those that use legumes as hosts and enough time growing for them to do their job. Potassium is readily available in renewable form from seaweed, kelp or wood ash.
I agree that it's not as clear as it might seem, and that in an ideal world it would be best to have all inputs and exports stay on the farm. But the world needs building materials; what's the most sustainable (or least destructive) way to supply them, if not growing them?
" what's the most sustainable (or least destructive) way to supply them, if not growing them?"
I'm all for growing them (wood, straw, etc.) as well. But I'd like to point out that unburnt earth (adobe, rammed earth, cob, etc.) is a huge untapped resource that doesn't impact farms and has virtually no GWP if the materials are locally sourced, as they should be. Obviously no single material is the perfect solution for all situations. But unburnt earth is a grossly under-utilized resource. What's needed is an infrastructure to be put in place in regions where it's most viable. That could mean initial subsidies to materials manufacturers and training for contractors, just as we subsidize residential PV installations.
And by the way, it's use is far from limited to warm-dry climates. It has a very long history in various parts of northern Europe for example.
The CobBauge Project out of Plymouth, UK and Grenoble, France is exploring options of combining earthen materials with straw to develop better insulating walls. Hopefully projects like this will help spread its use.
Good point. I sometimes get a bit overly perfectionistic. You are correct - their has to be tradeoffs. However, incorporating the amplifying effects of soil building into our computations - will likely lead to vastly different results.
So - if we are building structures - in my case - mostly homes - What are the the building techniques that will provide the desired living environment with the least environmental impact?
My current thinking is to incorporate as much earth construction and reclaimed materials - as is practical.
I have done many thousands of brd ft of reclaimed projects, I have not done earth construction- but I intend to.
Where would the earth come from? Won't that entirely eliminate soil structure from the place the earth was mined?
I think this is highly location dependent.
Most likely the optimal solutions ARE going to be location dependent. It's highly unlikely some one generic solution is going to be best for all locations. If I were to imagine an ideal future for housing construction it would include the efficient use of locally sourced sustainable materials involving the least amount of processing to turn them into usable form, things like adobe, straw, hemp, wool, etc. That is likely how we would keep initial carbon cost at a minimum. Then of course those materials would also have to enable us to build energy efficient shells, to keep operating costs down.
By the way, one thing you don't want in your earthen mix is fertile topsoil. So prime farmland is not the place to look for material. Anywhere where excavations are already happening (highrises in cities, industrial sites ...) are potential sources for material. Then of course there are the usual clay pits and so forth. Yes, inevitably a certain amount of damage to the environment may result. But for a start, this can be controlled through careful choice of the resources. And second, the damage from using petroleum based products, products shipped over long distances, high energy consuming cements, are likely to be far worse.
This article seems to, at least at times, conflate "green" with "cheap". If we're talking about carbon footprint of a one-off building, I don't see how monetary cost as any bearing on it. The three "yes, but" examples are all based on monetary cost. Triple pane windows cost a lot, but do they use a significant amount more carbon to build and install? I don't know, I kind of doubt it, especially in comparison to the listed alternative, solar panels. The article doesn't make any attempt to justify the statement.
The summing up has similar inconsistencies:
"If you have to build something, make the building small, simple, and inexpensive"
The article failed to make any case that being inexpensive saves any carbon, now or later.
"If you want to reduce your home’s carbon footprint...install a photovoltaic array"
This flies in the face of the main thesis of the article, which is reduce carbon use now rather than later. I don't know exactly how much carbon is embodied in the building, transport and installation of solar panels and all the associated hardware and electronics, but it's significant. Meanwhile, just using the electricity from the grid could in fact be much lower if your grid is nuclear or hydro powered. So why do solar panels get a pass from this rule? Seems like just personal bias.
The idea that when trying to build green, you need to account for more than just ongoing energy usage is valid. But there really isn't a straight line between that and "build the cheapest home you legally can".
How true - for example - reclaimed materials might be more expensive - but have a lower carbon foot print.
This Page,
As I've written many times, the cost of building materials does not correlate exactly with embodied carbon emissions, and it behooves any builder who advertises his or her services as "green" to avoid materials with high embodied carbon emissions (especially concrete and steel). That said, I think there is a higher likelihood than you are willing to admit that there is a rough correlation between cost and carbon emissions.
Let's take the typical $800,000 house: in almost all cases, it will have more carbon emissions than an inexpensive 1,200 square foot home. Of course, a wealthy individual can hire workers to make adobe bricks or stack straw bales -- and that's happened. But it's rare. All the newly built earthen homes and straw-bale homes I am aware of have been built by poor hippies who get help from family and friends to provide unpaid labor.
Wealthy people who hire architects and a GC to build them an $800,000 home are almost always responsible for significant carbon emissions--unlike my Vermont friends who live in humbler homes.
Let's give praise where praise is due--to the forward-thinking green builders who are beginning to imagine new ways to build homes from dirt and straw. But let's not pretend these rare exceptions are the rule.
Martin,
You've sparked a great discussion here, and that alone is the worthy effort-- helping to educate and shift perceptions toward the importance of tackling this problem. I realize I'm a couple months late to the discussion but I hope some are still following.
From where I sit the article 'misses the forest for the trees'. I imagine you know your audience well; they're folks that DO really care about this issue. Thus, I take issue with this sentiment: "If possible, don’t build anything."
No. I couldn't disagree more. The folks reading this are not the audience that should stop designing and building. Construction and renovation are never going to stop, much as that may seem the sage advice. Do more. Inspire. Challenge the status quo. There's no way to calculate the embodied carbon one well-informed individual or group can save and sequester armed with the right knowledge and priorities empowered to do the right thing. No tool is going to do that. AI is not going to do that. Regarding the wasteful projects we all detest that shouldn't be built, no one working on those is bothering to read GBA. It won't happen. The way to best the biggest offenders is the influence a market shift. Consumers must demand better, and be well informed on what better can look like.
Thank you for the discussion. Skylar's response #5 with accompanying chart I found particularly insightful.
Best regards,
Jason
Also, why the obsession with ductless? The goal is electrification and efficiency, sure, so i get the encouragement of heat pumps. But I can't recall exactly how many regret stories I've heard and read about the lack of distribution being the cause of buying a SECOND minisplit. Wasteful. That extra fraction of COP is not worth sacrificing distribution unless you/the client are truly prepared to tolerate temperature differential behind closed doors. Spend that fraction of extra COP efficiency for a right-sized system and ductwork. Comfort expectations and demands prevail in my experience.
Log in or become a member to post a comment.
Sign up Log in