Earth houses are easy to change and adapt as well as maintain. What happens with these when you need to make alterations? I see David Bergman is speculating along the same lines....
One of the great strengths of the pre-carbon buildings systems is that they are well understood by the people living in them - indeed, they probably helped build their house, and know it intimately. And when you need them, the repair materials are right there. You don't need to buy anything; no one is making a buck, they are just getting somewhere to live that they can afford to look after. Is that why they fell out of favour in the market-obsessed Global North?
No, it's because they don't offer standardized comfort. Between being vulnerable to deterioration, infestation with bugs, and changes in humidity affecting living conditions inside, you have a home that is in constant disrepair, dirty, and not to modern standards of comfort and consistency—especially if you want to sell your house to someone else.
Actually, the opposite is true: the ‘traditional’ solid wall materials and constructions which were universal before the Industrial Revolution are superb moisture and temperature buffers, and the maintenance was very simple. They are cool in hot weather, and were in the past also comfortable in cold weather because of the integral furnishings used to slash radiant heat loss (chiefly cloths hung on the walls to act as radiant barriers). Indeed, the traditional methods for creating thermal comfort in winter were so effective that people were able to keep their shuttered windows open even in winter, as we can see from the medieval illuminations. They have far fewer problems of damp and mould than most recent construction.
The lost fixtures and fittings are still critical to vernacular architecture in the Global South, but we forgot about them as we became addicted to using fossil fuels to try to solve all our problems. And to minimalism and the open plan, with acres of glass!
Those of us advising on historic buildings of ALL ages find that older structures tend to be very simple to care for. Particularly vernacular buildings: architects have done odd things at all points in history cf parapet gutters! In our experience, the problems for traditional construction pretty much all stem from the wrong materials being used for care and repair. Cement, plastic paints… these actively stop good systems working.
Regular lime washing is pretty much all you need for earth, whatever the climate; that and the proverbial ´good hat and a good pair of boots’! But you DO need lime washes and lime renders. Another modern fashion that has caused infinite problems has been the neglect or active removal of lime finishes, to reveal the underlying material. That’s a great way of creating a moisture problem.
We have ample proof of how well the traditional approaches work : for example 600 year old cob cottages in wet Devon that remain delightful places to live. And since they are very like subSaharan buildings, they should be able to cope with climate change!
We really do have to let go of the idea that we are better at constructing and managing buildings now than they were in the past: we’re not. Proof of the pudding is in the eating…
And, when it comes to ‘standardised comfort’: one has to ask « standardised for whom »? When? For which task? Comfort and health alike actually demand variation in conditions, and people-centred control. We do have some nice modern things to add here, such as ceiling fans: much better than a punkah-wallah. But there’s also a lot for us to relearn from 30000 years or so of pre-carbon practice.
"Actually, the opposite is true: the ‘traditional’ solid wall materials a the maintenance was very simple"
It was simple but very time consuming and as we all know time is money. Hence maintenance on them tends to be very expensive compared to something like a modern prefab.
"Indeed, the traditional methods for creating thermal comfort in winter were so effective that people were able to keep their shuttered windows open even in winter, as we can see from the medieval illumination"
Hold on that's not correct at all. They had the windows open because they ran fires 24/7 even in summer. They did it not because of the heat but to cause a steady draft of fresh air through the properties.
'They have far fewer problems of damp and mould than most recent construction."
Again, that's because they had constant current of air running through their properties. For example, UK Victorian properties were originally ventilated by keeping coal fires running and drawing in air and exhausting up the chimneys
When central heating was installed in the 60's and the properties were sealed (even if not very well) is when damp and mold problems started.
I am sure Lloyd would have something to say if we ventilated our houses Ike they did in 1920.
'Those of us advising on historic buildings of ALL ages find that older structures tend to be very simple to care for. " I have seen the numbers for some places - simple but eye watering expensive.
"Regular lime washing " - expensive!
I will give you a hint (before VB jumps in) why earth buildings will continue to be nothing other than interesting fare for TV programs and that is because modern people do not want to live like medieval peasants in mud huts.
" But there’s also a lot for us to relearn from 30000 years or so of pre-carbon practice."
There is literaly nothing for us to learn from back there.
I'm a conservative believer in the printing tech. I'm an outright hater on the 'concrete ink' being used. Rael has the right idea with 3d printed adobe/cob/earth. The Cobbauge project is another interesting approach. There are questions of scale, (can a city be built within the footprint of the amount of sub-soil it would need to take), and questions of durability and pests. It also takes you into bizzare economic circumstances, with material that is nearly free, machinery that is very expensive up front, and labour costs that are still uncertain. BUT it looks to be more flexible and wet weather tolerant than rammed earth approaches.
"Have I been wrong about 3D printed houses?" No. End of article.
It really could be that short. About a year ago there was a much longer article in The New Yorker, which could have been equally short: "Can 3-D Printing Help Solve the Housing Crisis?" No.
I was however glad to read your criticism about ⅔ through, about embedded carbon but mostly that the typology they are building is all wrong. We should not be celebrating anything that is developing single family car dependent houses. Especially when they are absolutely not gonna be affordable.
As for the construction, I'm always nervous the moment a developer/contractor talks about needing less guys. That's someone with a stern look at the bottom line, not at the planet or the people. And remember that that, it is only the walls that are being printed, the foundation and the roof is still typical assembly. Why the need for 3D-printing in the first place, when prefab wall assembly has been around for +60 years, it can be as durable, done faster, it can be stacked and used in dense urban areas.
Let's maybe not give the 3D printing guys any more attention, than to check in once a year, five years, to see that they are still not managing to meet the requirements of modern construction, but boy do that machine still look cool.
I love that you champion changing your mind and admitting to being wrong but I wan't to reinforce my prejudices against 3D printing! Something feels wrong! Good comments including on carbon and practicality which can all be analysed rationally and may have solutions as commenters have suggested. I'm happy to assume a cheap, washable, smooth, insulating material can be made from dirt and carbon sequestering natural bio-additives that are nutritious for kids but poisonous for pests.
There is mention by you and in the comments of a shift from labour to capital which is a more fundamental concern for me. Meaningful work is getting thin on the ground and we can't all be innovative tech start up successes or influencers even if we aspire to that. As usual, a pyramid image seems appropriate.
3D printing has been a game changer where it solves a formerly intractable problem such as complex titanium mesh components used to repair certain broken bones in surgery or as already mentioned, parts for rocket engines. But friends with a 3D polymer printer who need a simple coat hook will print one, excited to have found something they need that they can actually print in plastic. A solution looking for a problem. This simple coat hook can be a quirky and 'creative' as you like, unconstrained by the usual limitations of wood or hand worked metal but it lacks soul. And I say that as a born again atheist. My late Uncle, an excentric commercial artist, would fashion a hook out of a bit of wire in a matter of minutes to solve an immediate storage problem, each was unique to him like a signature and would raise a smile.
Home 3D printers could perhaps evolve to produce items indistinguishable from the best hand made objects. We see hipster cafes and bars with fake industrial patinated interiors. Imagine the Turing test for AI generated 3D printed sculptures or craft items. The Chess and Go masters have been beaten by computers soon a Zen master might be fooled by a generative AI, 3D printed tea bowl. Such headline making victories distract from the loss of craft and meaning in every day life. Perhaps unsliced bread is the best thing since sliced bread.
High carbon load. High energy load. Aesthetically grotesque. A good example of solutionism and commodification as a form of climate denialism. Abject. Embarassing. Clownish.
I love the potential that 3D printing - hopefully not utilizing conventional cement - has, but have a couple of pragmatic points to add:
1. How are wall repairs performed (say, for plumbing or electrical maintenance or changes)? Never mind moving or adding walls. Circularity demands repairability and adaptability.
2. Doesn't the Bjarke curvy design add a lot of exposed exterior surface and intersections? And do those exterior walls have any thermal breaks? Are their R values sufficient? (And, related to the curves, it's a lot harder to furnish rooms with curved walls.)
I share our concerns. While there is a lot of geewizardy going on here, there are also lots of CO2 emissions involved. I would like to see them incorporate low carbon cement from companies like Sublime Systems. And the urban sprawl aspect is concerning. We need communities where everything does not start with getting in a can and driving somewhere. In a sense, this development is just a 21st century version of Levittown.
Lloyd- I appreciate your insights in this piece. To your point, the inevitable 2-car garage phenomenon is really something that hasn't yet been fully solved. A great reminder of the work still to be done. Hope you're well this week. Cheers, -Thalia
"But they say, “compared to traditional construction, the company says that 3D printing homes is faster, less expensive, requires fewer workers, and minimizes construction material waste.”"
That in itself makes me very suspicious of this project. Sounds like a developer desperately trying to cover up the disadvantages they found along the way.
It's also not true when you include prefab, which beats it on every metric.
Everything—even when ignoring the carbon aspect entirely.
Lloyd is not wrong about the dust collecting on the surface of these interior walls. Texturally, it would make it difficult to keep clean (doubly so for grease in a kitchen), and heaven help an owner with small children who chose to use markers on them to draw. Interior concrete walls are a verifiable PITA (I owned one in a central Phoenix neighborhood from 2005-12) and trying to run new electrical or plumbing is a nightmare. Hanging pictures or a new TV? Fuhgeddaboudit. Then you have the added cost, hassle of needing a boosted WiFi signal, and unnecessary structural integrity to deal with—presumably concrete interior walls make for stronger, tornado-resistant structures, but at what cost? The entire house doesn't need to be an above-ground bunker, only a single room—and preferably one that's underground.
You also don't need INTERIOR walls of concrete to keep bugs and water outside; a properly constructed and sealed exterior handles that on its own without additional cost. I've never known wasps, ants, or termites to infiltrate the interior walls when their food source is located outside of the house ... so that seems like an even further stretch of a selling point.
I'm with Lloyd on this 100% but for different reasons. I think it's a novelty and exercise in vanity.
"Lloyd is not wrong about the dust collecting on the surface of these interior walls. Texturally, it would make it difficult to keep clean (doubly so for grease in a kitchen), "
And I get to disagree with VB - frame this as well. Look, I claim no special knowledge in this at all OTHER than to say, as with many tech products, this is merely Version 2.0 (from the railed version to the articulated arm). Which means, as long as the $$ doesn't run out, Version 3.0 is already in process. All one needs is good ideas. And the only folks that have a monopoly on good ideas are those that HAVE good ideas.
I looked at that head unit and when I read VB's "dust dismissal", I naturally thought "oh, an add on device - a "smoother" device to make that irrelevant. Or a "buffer sander" or some such devices. Sure, more development but "add ons" like the myriad adds to a gun, Bobcat machine, or any other of thousands of "things", like a Kitchen Aid blender. They've seemed to have licked the hard parts so add-on functionality is mere a case of "what can you think of?".
And think of all of the additive engineering being done where entire products are metal-sintered printed eliminating tons of individual parts as they simply printed in (think jet and rocket engines for extreme examples). Think tool-swiveling CNC machine heads for more intricate voids for snaking wires and/or plumbing. It can't just be me thinking beyond what ICON has already created, right? YMMV.
See how much simpler #3 is from #2 and with better performance at less weight. And I'm thinking less manufacturing costs. Estimated: Raptor 1 was $1M, Raptor 2 at $250K, and the initial cost for Raptor 1 Serial Number 1 at $250K to $500K (cost subject to production runs).
I'm betting that ICON will follow a similar slope, albeit at a MUCH slower pace (SpaceX rapid design/test/fail/rebuild process rate is absurd but gets usable product FAST).
I missed how the thermal enclosure is obtained, and also how the services are incorporated.
I can imagine (absent other objections noted in these comments) that the "ink" could be a more benign mix ultimately, and even more regionally appropriate.
I read about this project a year ago too. The missing part in the carbon question is the savings from all the materials they don't have to use , the floors are polished concrete , so no flooring, no drywall, paint, baseboards, no stucco exterior finish, and way less workers driving to the site in pickups. The machines can run 24 hours a day. This is definitely a solution for southern climates where mould, mildew and blistering heat have long been ignored. Construction is mired in 19th century thinking. Innovation only happens when you stick your neck and your wallet out and try something. Good on them.
Maybe it’s appropriate in certain places? Christian was working in his family’s hometown in Guatemala. I’m also intrigued by 3D printing with organic materials (like earth or coffee grounds) rather than concrete but as you rightly point out, it’s unlikely to scale.
Ah, whenever I hear of printing a house, I think of how similar it seems to the worldwide methods of treading down mud in layers to make building envelopes - only much much more expensive and much much less sustainable... https://www.architectural-review.com/essays/inhabiting-the-earth-a-new-history-of-raw-earth-architecture You don't need a printer: feet will do just FINE!
Earth houses are easy to change and adapt as well as maintain. What happens with these when you need to make alterations? I see David Bergman is speculating along the same lines....
One of the great strengths of the pre-carbon buildings systems is that they are well understood by the people living in them - indeed, they probably helped build their house, and know it intimately. And when you need them, the repair materials are right there. You don't need to buy anything; no one is making a buck, they are just getting somewhere to live that they can afford to look after. Is that why they fell out of favour in the market-obsessed Global North?
No, it's because they don't offer standardized comfort. Between being vulnerable to deterioration, infestation with bugs, and changes in humidity affecting living conditions inside, you have a home that is in constant disrepair, dirty, and not to modern standards of comfort and consistency—especially if you want to sell your house to someone else.
In a lot of climates maintenance would be a very heavy load. In order to minimise that you would have to include a lot of modern products/processes.
Actually, the opposite is true: the ‘traditional’ solid wall materials and constructions which were universal before the Industrial Revolution are superb moisture and temperature buffers, and the maintenance was very simple. They are cool in hot weather, and were in the past also comfortable in cold weather because of the integral furnishings used to slash radiant heat loss (chiefly cloths hung on the walls to act as radiant barriers). Indeed, the traditional methods for creating thermal comfort in winter were so effective that people were able to keep their shuttered windows open even in winter, as we can see from the medieval illuminations. They have far fewer problems of damp and mould than most recent construction.
The lost fixtures and fittings are still critical to vernacular architecture in the Global South, but we forgot about them as we became addicted to using fossil fuels to try to solve all our problems. And to minimalism and the open plan, with acres of glass!
Those of us advising on historic buildings of ALL ages find that older structures tend to be very simple to care for. Particularly vernacular buildings: architects have done odd things at all points in history cf parapet gutters! In our experience, the problems for traditional construction pretty much all stem from the wrong materials being used for care and repair. Cement, plastic paints… these actively stop good systems working.
Regular lime washing is pretty much all you need for earth, whatever the climate; that and the proverbial ´good hat and a good pair of boots’! But you DO need lime washes and lime renders. Another modern fashion that has caused infinite problems has been the neglect or active removal of lime finishes, to reveal the underlying material. That’s a great way of creating a moisture problem.
We have ample proof of how well the traditional approaches work : for example 600 year old cob cottages in wet Devon that remain delightful places to live. And since they are very like subSaharan buildings, they should be able to cope with climate change!
We really do have to let go of the idea that we are better at constructing and managing buildings now than they were in the past: we’re not. Proof of the pudding is in the eating…
And, when it comes to ‘standardised comfort’: one has to ask « standardised for whom »? When? For which task? Comfort and health alike actually demand variation in conditions, and people-centred control. We do have some nice modern things to add here, such as ceiling fans: much better than a punkah-wallah. But there’s also a lot for us to relearn from 30000 years or so of pre-carbon practice.
"Actually, the opposite is true: the ‘traditional’ solid wall materials a the maintenance was very simple"
It was simple but very time consuming and as we all know time is money. Hence maintenance on them tends to be very expensive compared to something like a modern prefab.
"Indeed, the traditional methods for creating thermal comfort in winter were so effective that people were able to keep their shuttered windows open even in winter, as we can see from the medieval illumination"
Hold on that's not correct at all. They had the windows open because they ran fires 24/7 even in summer. They did it not because of the heat but to cause a steady draft of fresh air through the properties.
'They have far fewer problems of damp and mould than most recent construction."
Again, that's because they had constant current of air running through their properties. For example, UK Victorian properties were originally ventilated by keeping coal fires running and drawing in air and exhausting up the chimneys
When central heating was installed in the 60's and the properties were sealed (even if not very well) is when damp and mold problems started.
I am sure Lloyd would have something to say if we ventilated our houses Ike they did in 1920.
'Those of us advising on historic buildings of ALL ages find that older structures tend to be very simple to care for. " I have seen the numbers for some places - simple but eye watering expensive.
"Regular lime washing " - expensive!
I will give you a hint (before VB jumps in) why earth buildings will continue to be nothing other than interesting fare for TV programs and that is because modern people do not want to live like medieval peasants in mud huts.
" But there’s also a lot for us to relearn from 30000 years or so of pre-carbon practice."
There is literaly nothing for us to learn from back there.
I'm a conservative believer in the printing tech. I'm an outright hater on the 'concrete ink' being used. Rael has the right idea with 3d printed adobe/cob/earth. The Cobbauge project is another interesting approach. There are questions of scale, (can a city be built within the footprint of the amount of sub-soil it would need to take), and questions of durability and pests. It also takes you into bizzare economic circumstances, with material that is nearly free, machinery that is very expensive up front, and labour costs that are still uncertain. BUT it looks to be more flexible and wet weather tolerant than rammed earth approaches.
https://southwestcontemporary.com/ronald-rael-3d-printed-abode/
"Have I been wrong about 3D printed houses?" No. End of article.
It really could be that short. About a year ago there was a much longer article in The New Yorker, which could have been equally short: "Can 3-D Printing Help Solve the Housing Crisis?" No.
I was however glad to read your criticism about ⅔ through, about embedded carbon but mostly that the typology they are building is all wrong. We should not be celebrating anything that is developing single family car dependent houses. Especially when they are absolutely not gonna be affordable.
As for the construction, I'm always nervous the moment a developer/contractor talks about needing less guys. That's someone with a stern look at the bottom line, not at the planet or the people. And remember that that, it is only the walls that are being printed, the foundation and the roof is still typical assembly. Why the need for 3D-printing in the first place, when prefab wall assembly has been around for +60 years, it can be as durable, done faster, it can be stacked and used in dense urban areas.
Let's maybe not give the 3D printing guys any more attention, than to check in once a year, five years, to see that they are still not managing to meet the requirements of modern construction, but boy do that machine still look cool.
I love that you champion changing your mind and admitting to being wrong but I wan't to reinforce my prejudices against 3D printing! Something feels wrong! Good comments including on carbon and practicality which can all be analysed rationally and may have solutions as commenters have suggested. I'm happy to assume a cheap, washable, smooth, insulating material can be made from dirt and carbon sequestering natural bio-additives that are nutritious for kids but poisonous for pests.
There is mention by you and in the comments of a shift from labour to capital which is a more fundamental concern for me. Meaningful work is getting thin on the ground and we can't all be innovative tech start up successes or influencers even if we aspire to that. As usual, a pyramid image seems appropriate.
3D printing has been a game changer where it solves a formerly intractable problem such as complex titanium mesh components used to repair certain broken bones in surgery or as already mentioned, parts for rocket engines. But friends with a 3D polymer printer who need a simple coat hook will print one, excited to have found something they need that they can actually print in plastic. A solution looking for a problem. This simple coat hook can be a quirky and 'creative' as you like, unconstrained by the usual limitations of wood or hand worked metal but it lacks soul. And I say that as a born again atheist. My late Uncle, an excentric commercial artist, would fashion a hook out of a bit of wire in a matter of minutes to solve an immediate storage problem, each was unique to him like a signature and would raise a smile.
Home 3D printers could perhaps evolve to produce items indistinguishable from the best hand made objects. We see hipster cafes and bars with fake industrial patinated interiors. Imagine the Turing test for AI generated 3D printed sculptures or craft items. The Chess and Go masters have been beaten by computers soon a Zen master might be fooled by a generative AI, 3D printed tea bowl. Such headline making victories distract from the loss of craft and meaning in every day life. Perhaps unsliced bread is the best thing since sliced bread.
".....faster, less expensive (?), requires fewer workers, and minimizes construction material waste."
Shareholders over people again?
How are these houses addressing a housing crisis?
High carbon load. High energy load. Aesthetically grotesque. A good example of solutionism and commodification as a form of climate denialism. Abject. Embarassing. Clownish.
tell me what you really think!
I love the potential that 3D printing - hopefully not utilizing conventional cement - has, but have a couple of pragmatic points to add:
1. How are wall repairs performed (say, for plumbing or electrical maintenance or changes)? Never mind moving or adding walls. Circularity demands repairability and adaptability.
2. Doesn't the Bjarke curvy design add a lot of exposed exterior surface and intersections? And do those exterior walls have any thermal breaks? Are their R values sufficient? (And, related to the curves, it's a lot harder to furnish rooms with curved walls.)
I share our concerns. While there is a lot of geewizardy going on here, there are also lots of CO2 emissions involved. I would like to see them incorporate low carbon cement from companies like Sublime Systems. And the urban sprawl aspect is concerning. We need communities where everything does not start with getting in a can and driving somewhere. In a sense, this development is just a 21st century version of Levittown.
Lloyd- I appreciate your insights in this piece. To your point, the inevitable 2-car garage phenomenon is really something that hasn't yet been fully solved. A great reminder of the work still to be done. Hope you're well this week. Cheers, -Thalia
"But they say, “compared to traditional construction, the company says that 3D printing homes is faster, less expensive, requires fewer workers, and minimizes construction material waste.”"
That in itself makes me very suspicious of this project. Sounds like a developer desperately trying to cover up the disadvantages they found along the way.
It's also not true when you include prefab, which beats it on every metric.
>>"What’s not to love?"
Everything—even when ignoring the carbon aspect entirely.
Lloyd is not wrong about the dust collecting on the surface of these interior walls. Texturally, it would make it difficult to keep clean (doubly so for grease in a kitchen), and heaven help an owner with small children who chose to use markers on them to draw. Interior concrete walls are a verifiable PITA (I owned one in a central Phoenix neighborhood from 2005-12) and trying to run new electrical or plumbing is a nightmare. Hanging pictures or a new TV? Fuhgeddaboudit. Then you have the added cost, hassle of needing a boosted WiFi signal, and unnecessary structural integrity to deal with—presumably concrete interior walls make for stronger, tornado-resistant structures, but at what cost? The entire house doesn't need to be an above-ground bunker, only a single room—and preferably one that's underground.
You also don't need INTERIOR walls of concrete to keep bugs and water outside; a properly constructed and sealed exterior handles that on its own without additional cost. I've never known wasps, ants, or termites to infiltrate the interior walls when their food source is located outside of the house ... so that seems like an even further stretch of a selling point.
I'm with Lloyd on this 100% but for different reasons. I think it's a novelty and exercise in vanity.
I have to frame this, it is the first time we have ever agreed about anything!
Actually, I believe you agreed with him on something about 5 years ago on TH. Many people required trauma counselling.
Heh!
"Lloyd is not wrong about the dust collecting on the surface of these interior walls. Texturally, it would make it difficult to keep clean (doubly so for grease in a kitchen), "
And I get to disagree with VB - frame this as well. Look, I claim no special knowledge in this at all OTHER than to say, as with many tech products, this is merely Version 2.0 (from the railed version to the articulated arm). Which means, as long as the $$ doesn't run out, Version 3.0 is already in process. All one needs is good ideas. And the only folks that have a monopoly on good ideas are those that HAVE good ideas.
I looked at that head unit and when I read VB's "dust dismissal", I naturally thought "oh, an add on device - a "smoother" device to make that irrelevant. Or a "buffer sander" or some such devices. Sure, more development but "add ons" like the myriad adds to a gun, Bobcat machine, or any other of thousands of "things", like a Kitchen Aid blender. They've seemed to have licked the hard parts so add-on functionality is mere a case of "what can you think of?".
And think of all of the additive engineering being done where entire products are metal-sintered printed eliminating tons of individual parts as they simply printed in (think jet and rocket engines for extreme examples). Think tool-swiveling CNC machine heads for more intricate voids for snaking wires and/or plumbing. It can't just be me thinking beyond what ICON has already created, right? YMMV.
As an example, look at these SpaceX Raptor engines that fly the Falcon 9, Superheavy, and Starship from the aspect of "continual improvement" some of which is assisted by additive manufacturing: https://www.nextbigfuture.com/2024/08/spacex-reveals-raptor-3-engine-and-specifications.html
See how much simpler #3 is from #2 and with better performance at less weight. And I'm thinking less manufacturing costs. Estimated: Raptor 1 was $1M, Raptor 2 at $250K, and the initial cost for Raptor 1 Serial Number 1 at $250K to $500K (cost subject to production runs).
I'm betting that ICON will follow a similar slope, albeit at a MUCH slower pace (SpaceX rapid design/test/fail/rebuild process rate is absurd but gets usable product FAST).
I missed how the thermal enclosure is obtained, and also how the services are incorporated.
I can imagine (absent other objections noted in these comments) that the "ink" could be a more benign mix ultimately, and even more regionally appropriate.
I read about this project a year ago too. The missing part in the carbon question is the savings from all the materials they don't have to use , the floors are polished concrete , so no flooring, no drywall, paint, baseboards, no stucco exterior finish, and way less workers driving to the site in pickups. The machines can run 24 hours a day. This is definitely a solution for southern climates where mould, mildew and blistering heat have long been ignored. Construction is mired in 19th century thinking. Innovation only happens when you stick your neck and your wallet out and try something. Good on them.
One of my former students did his masters thesis on this. Wrote about it here for my podcast, Building Hope: https://open.substack.com/pub/juliegabrielli/p/yes-you-really-can-3-d-print-a-house?utm_campaign=post&utm_medium=web
Maybe it’s appropriate in certain places? Christian was working in his family’s hometown in Guatemala. I’m also intrigued by 3D printing with organic materials (like earth or coffee grounds) rather than concrete but as you rightly point out, it’s unlikely to scale.