For those who didn't read the article: the chemistry of Portland cement works against it. Production requires heating the calcium carbonate to a high temperature to extract carbon dioxide from it. Which obviously produces large amounts of CO2 proportional to concrete production. However, concrete also absorbs carbon dioxide from the air over its lifetime. So the measured emissions aren't the entire story.
Perhaps in future we will consider this an excellent source of carbon dioxide for the production of various hydrocarbons. I've heard of several efforts to create octane using carbon dioxide from the air, but you need a large amount of energy to extract a useful amount of CO2. Well this would be a good source of high concentration CO2. Perhaps not for octane ( we should really be moving away from combustion engines ) but perhaps plastics and other products that are currently derived from crude oil.
I don't know which country you have in mind but in Europe the construction industry by law is obligated to design concrete structures for residential buildings that ensures a useful life of at least 50 years, and by definition that means that the building structure shall not require maintenance for at least 50 years.
Moreover, concrete as a widespread structural material is relatively new, and city centers are still packed with contrete buildings that were built when the technology started popping up.
In fact, in general a building with concrete structure is only demolished when it's not possible to retrofit or renovate it effectively, due to unrelated reasons such as increasing occupation density that would not be cost-effective by reinforcing the concrete structure.
My point is that concrete structures are not demolished with enough frequency to be of any concern. The main reason is that concrete structures are simply too expensive to be demolished, moreso in urban centers. Thus your concern simply isn't relevant in the real world because economics already impose the same restrictions that are expressed in your environmental concerns.
The only factor that the use of concrete plays in this scenario is that concrete structures are expensive and time-consuming to demolish. If the investment makes financial sense then the choice of building material doesn't make any difference.
Turning the cons of concrete into pros (carbon-cured concrete)
>carbon-cured concrete: in carbon curing, concrete is cured with gaseous carbon dioxide, from the plastic phase forward. The curing of concrete with pressurized carbon dioxide generates not only the ordinary reaction products of cement but also carbonate-based reaction products. Consequently, the process binds carbon dioxide, and it is even possible to make the final product carbon negative if ordinary cement is replaced with alternative binders with a low carbon footprint.
The Carbon Reuse Economy: Transforming CO2 from a pollutant into a resource
The alternative is to build from wood whenever possible, and capture extra cabon in building material. This increases market need for wood and therefore forestation.
My parents live in a house that was originally built in the 1890s. It first had a fire place and wood stove for eating/cooking (surmised via chimneys), then it had gas lighting (some pipe are still in the walls), then it knob-and-tube lighting, then modern electrical lighting and cooking.
Walls were replaced, insulation added, etc. Lots of internal changes.
But the foundations and external brick is original (AFAICT).
Buildings are just boxes for people which keep the cold/heat/moisture at a comfortable level. As long as the "bones" of the buildings are good seismically, the "skin" has proper environmental control, then you can shuffle the inside around without too many issues.
Design/build things with minimal internal load-bearing walls and things can be shuffled fairly easily. Perhaps also use trusses instead of rafters as well for easier running of piping/wire.
So true. With the knowledge we have now about building materials you could create a very versatile, rigid, energy efficient base structure that lasts > 100 years, and adapt/update the internals to the current needs. You could even change the room layout completely.
I live in Europe and I can't understand why houses in the US are built with wood and drywall. It surely must be cheaper to use bricks/concrete and then renovate it fully every 20 years, or am I wrong here?
Milling large trees down to 2x4s and coupling it to drywall to build homes that don't last is a travesty.
The bulk of NZ houses are wooden, and have been for its entire history. They are also cold and are often damp, though these problems can be solved with decent building practices.
Concrete and brick are not that desirable in an earthquake prone country.
And yes, milling big old trees is bad. They are now made of treated pine, which comes with its own environmental concerns.
This one is about energy efficiency: https://www.youtube.com/watch?v=mBOvflXoWlw
I'm really interested in finding more videos like this because his videos go past "Home Depot said this is energy efficient", he instead tests these concepts and apparently works with different colleges that research these ideas.
I would think that renovations are much easier to do, regardless of the time interval between them, with wood and drywall. Drywall can be torn apart with by someone with just their hands; wood may need some cutting, but once in shorter pieces, can often just be yanked. Even a large house can probably be gutted/internally-exposed in a day or two.
With any kind of masonry you have to swing a sledge hammer with a lot of force or bring in jack hammers. Once set, concrete will resist a lot of force against it, which is why it's generally used for slabs and foundations.
It also depends on what you mean by renovate: often changes are in internal layout, so if one uses good design techniques for the shell:
And floor trusses to reduce/eliminate internal load-bearing walls:
It give completely flexibility on what can be done inside the box.
Wood is also fairly cheap and plentiful in North America.
As for drywall: what are the alternatives for internal walls? Lath and plaster?
Some growth in popularity for wood in Europe; some Swiss examples:
But in brick houses renovation often means fixing what's broken and adding modern technologies such as insulation. Moving or adding walls can easily become quite a large scale project.
Wood structures have no issues lasting 100+ years as long as they’re protected from water and termite damage.
California? They last a long time. Deep South? I assume they don’t last as long. Canada? They last a long time.
At least a fifth of the UKs housing stock is over a century old, so the answer to that question is yes, if they're built properly...
The insulation, pipes, and wiring all are quite inferior to modern standards.
However, buildings built today to today's modern standards (with a little foresight) could easily be fine 100 years in the future. I'm not talking about fragile glass showpieces, but simple properly insulated homes built from durable materials.
My biggest issue with old homes is the layouts tend to be weird for today’s uses. Where I live many of the homes have a lot of small rooms and and narrow doorways instead of larger ones, for instance.
This of course goes back to conserving heat. But it makes house hunting difficult when trying to find a house with a layout you like.
The house where I grew up was made before Portland came to our zone, so it was made of lime mortar and rocks, some of them as big as a mellon, I found out when I tried to drill the walls to put a basketball basket.
It was demolished in the eighties, but not because it was in bad shape. I met the bulldozer operator years later and he recalled how he had a hard time with it.
I'm sure it would have been fine today, when it would be 100 y.o. or close. And I'm sure there's no other place where I'd rather live. It was cool in the summer, easy to warm in the winter, no mold, little noise from the outside.
Obviously, we do.
To put it in terms that may be easier to understand, we do not want to demolish a building when it serves all functional requirements.
Double so if they have urban and cultural value.
I suggest you visit places such as Amsterdam, where most of the city center was built in the 17th century and it's glorious.
I don't want a new house. Why? Because I refuse to live in a house with no natural ventilation. Most modern houses need air condition or at least ventilation systems, because they need to be so energy efficient, that there is no other way to get fresh air in. The fact that a house needs to be pressure tested seems insane.
Sure you can leave the windows open, but that defeats the purpose. Modern home needs to be ventilated three times a day, that means opening all the windows in the morning, when you get home in the afternoon and before going to bed. How many people will remember to do that?
The air in a modern home is often so dry that my nose start running the minute I enter. I don't want to live in that sort of climate.
Depending on the country, I think people should aim for home built from the late 1940 to mid 1970. Most likely additional isolation and new windows have been added over the years, making them reasonably energy efficient.
What's the alternative, building intentionally leaky houses? Better to be able to control the leaks to your benefit, aka active ventilation.
> Sure you can leave the windows open, but that defeats the purpose.
Actually the purpose of wind-ows is to let the wind in - no pun, that's the actually etymology of the word,
(also in Spanish: ventana originally meant "for venting").
Even in an old air-leaky house if you don't open your windows, the ventilation is happening through your walls, using them as an air filter which they were not designed to be, and in the process pulling moisture through them, which can cause all kid of bad stuff to grow in them. You shouldn't rely on such passive depressurization for ventilation, as it depends totally on pressure differences between indoors and outdoors.
> Most modern houses need air condition or at least ventilation systems, because they need to be so energy efficient, that there is no other way to get fresh air in.
There absolutely are ways to get fresh air in and dirty air out, including the following:
- Exhaust ventilation systems (i.e. whole home extractor fans)
- Balanced ventilation systems
- Energy/Heat Recovery Ventilation systems.
The poorly ventilated houses you are referring to were built between the 80s and 90s - yes they have ventilation issues. I know this because I own such a house and have fixed the ventilation issues with solutions from the list above.
Today in most areas, some form of mechanical ventilation is required by code on new construction, and has been for 15 or so years.
In cold climates, the ability to safely humidify a house depends mainly on having good enough insulation and air sealing that the indoor humidity doesn’t condense on cold surfaces and rot the building. This is especially relevant near windows.
So if you want decent indoor humidity when it’s genuinely cold out, you want double- or triple-paned windows with insulated edges, proper air sealing near the windows, and possibly even an energy recovery ventilator.
(Or you can live in an old house, spend stupid amounts of money to heat it all the way to 63 degrees for a few hours a day, be cold and dry, and wonder what the heck anyone was thinking when they designed their single-pipe steam heating system.)
P.S. It is supposedly possible to properly design a single pipe steam heating system that achieves a comfortable temperature in more than one room. If so, I have never seen such a thing.
If you are interested in learning more about this "possibility", particularly if you have a steam system that you hate, you'd probably enjoy Dan Holohan's books. His basic thesis is that when designed and installed, they worked well, but the knowledge necessary to keep them functional has been lost over the years. Here's a New Yorker profile of him: https://www.newyorker.com/magazine/2016/01/04/steamed-the-jo...
I don't really understand your objection. in a leaky old style building without an effective moisture/thermal barrier, you don't get to choose whether ventilation is happening; it always is. with modern sealing, you can open the windows if you prefer fresh air, or you can enjoy much more efficient AC/heat if you don't. why couldn't you live in a modern home and just leave the windows open? it's easy to get a good draft going in any multifloor building with windows.
How can something powered by electricity/natural gas/etc be more efficient than simply opening the windows and letting Mother Nature do the work?
Now the thing is that I like old houses.
So, just pay a nice marketing team to make sure people love old houses (after all, we have marketing team that can sell poison such as cigarettes or carbon dioxide).
Or, as you said, just build with something easier to handle such as wood (provided you recycle it, else it'll go back to biomass, releasing its CO2 again)
It’s something of a design failure of modern buildings where walking outside when it’s 80f is pleasant but inside you need AC at those temperatures.
The citation for this claim doesn't seem very robust. It links to the Ellen MacArthur foundation website, but just to the front page. After some of my own Googling it looks like it's coming from this publication . This study drew up some estimates on the amount of textiles produced and discarded as well as a simple conversion of 4.7 Kg of CO2 for every Kg of textiles produced. The source for this ratio of CO2 to kilogram of textiles simply says "McKinsey Analysis"/
Say Australia digs up some coal, ships it to China, it’s used to power factories and smelters to produce goods, then those goods are shipped to and used by Americans. Is there consensus on who the pollution from burning coal gets tied to? Or does it vary per report and article?
Sustainable energy without the hot air does this, it's a great book though I've heard it's somewhat outdated now.
It’s great that both approaches exist, because they surface different conclusions. If you want to see where the actual emissions are being emitted, or what “industry” they’re from, then the production-based accounting will give you that. If you instead want to see what different consumer-level behaviors are responsible for most emissions then you’ll need a consumption-based accounting.
That duality is what makes it hard for people to grok carbon accounting estimates sometimes.
- Scope 1 emissions are direct emissions from owned or controlled sources.
- Scope 2 emissions are indirect emissions from the generation of purchased energy.
- Scope 3 emissions are all indirect emissions (not included in
scope 2) that occur in the value chain of the reporting company, including both upstream and downstream
So grain purchased and shipped to the animals is measured under Scope 3. Powering the lights and machinery on the farm is Scope 2.
It's tricky and inexact to do GHG accounting, but the same methodology and emissions factors are used everywhere so at least it's comparable between companies and products.
Cattle produces a lot of methane, which has a very powerful greenhouse effect, a lot more powerful than CO2. So while it does not contribute to CO2 emissions that much, it contributes to the greenhouse effect proportionally a lot more.
We'll clearly have to use something else for building moon bases.
Co2 is released in the production of cement (in cement factories). Once it’s used in the buildings it actually sucks back some of that co2 back during the first years.
In biosphere cement was actually a carbon sink, but it threw the system off balance, because it caused bacteria to eat more oxygen than expected.
If we do that, we will have to resupply the O2 in some way other than converting CO2 back to oxygen. Either shipping new gas to the moonbase, or having the moonbase convert organic material on the moon to O2 (which sounds a lot more expensive and difficult than having plants scrub CO2 into O2 for us).
This is also not to mention the other valuable things were venting with the CO2 (heat for one; I assume keeping a moonbase at a livable temperature would be a struggle). Your scrubber also has to be able to replenish the gas while it's venting, or you risk having rapidly fluctuating pressures in the moonbase. Which is going to be uncomfortable for living things, and will require whatever the moonbase is made out of to be able to handle those changes in pressure (again, I imagine having pressure that fluctuates like a bounce house with a group of sugared up children in it is less than ideal). It's not hard to imagine a non-rigid structure like the base from The Martian bouncing off the surface of the moon when it rapidly constricts from venting CO2 and then rapidly inflates as the O2 replenisher kicks on. It would become a massive bouncy ball in 0G.
The biggest extravagance is space. Having space (I.e. detached houses) has a knock on effect of increased emissions of everything. Increased energy usage to transport mass increased distance.
Also, as pointed out below, the "fashion industry" includes all clothing. Beyond food and water, I'm not sure what would be more necessary than clothing.
I suspect cheap, disposable clothing is driving much more emissions.
Is there any data supporting this? Because while I think this is our intuition, i.e. "it's expensive therefore it's better quality," I wonder if there's any way we could verify this other than anecdotal evidence.
I think it is common sense that emissions are far lower for extreme-luxury clothing that can be repaired and is timeless verses disposable clothing that last one or two years.
Using CLT (and passive house principles) can reduce the total CO2 emmissions of a house by 90% in its total life span. The wood in CLT stores carbon and the passive house principles reduces energy needs.
For those unfamiliar with CLT, this is a high tech building material suitable for making e.g. sky scrapers or other types of buildings. It's much lighter and stronger than concrete. Because it is lighter, you save a lot of fuel transporting it. It's fire resistant and rot resistant because it is chemically treated. It's also much easier to work with as you can drill, glue, saw, etc. it. Additionally, you can do this off site meaning actual onsite construction activities are a lot more straight forward, less noisy, and much less wasteful. Think Ikea for buildings.
To sketch you a picture of how awesome this stuff is, the Japanese are planning to build a 1100 feet skyscraper made of wood, steel, and clt in Tokyo, which is of course a city that regularly sees earthquakes and tropical storms. https://www.archdaily.com/889142/japan-plans-for-supertall-w....
The biggest challenge is going to be simply scaling the production of this material and transitioning the construction industry to mostly using this instead of concrete. Right now it's kind of a novelty / niche thing and it is going to take a while to reach efficiencies and economies of scale we have with concrete today. It's not exactly cheap (yet) but it could become cheaper long term; especially if you consider all the benefits (technical and environmental).
Other engineered woods such as plywood and MDF are around 10% adhesive (glue), often urea-formaldehyde, which can produce hazardous chemicals during recycling or incineration. CLT, however, is below 1% adhesive, and typically uses a bio-based polyurethane. The planks are bonded together under heat and pressure to fuse that small amount of adhesive using the moisture of the wood. To look at, smell and touch, it’s as pure wood as a child’s tree house – knots and all.
In any case, there are already quite a few buildings that use this so, I'd say this is a non-issue.
There is also CLT without glue. Check https://www.youtube.com/watch?v=4j_UjIshzMc where Matt Risinger is visiting a Swiss factory where they use wooden (berch?) nails and dowel pins in stead of glue. And by using more layers they also need no insulation. Gives R=24...
There's also a report about a glulam burn test, something I was quite curious about.
"As the main vertical/lateral structural elements and the floor spanning systems of Mjøstårnet are constructed from timber, the building is considered an all-timber structure."
With rigorous humidity and temperature regulation, some adhesives have an as-yet undetermined lifespan. I'm still looking for transportable passive designs without active mechanical assistance that keep humidity at or below 40% and temperature variation to within ±10° C in temperate zones.
"passive designs without active mechanical assistance" - do you mean passive (highly insulated, air tight) designs without mechanical ventilation?
Yes, PassivHaus or even NetZero type standard, but without an electrically-powered ERV. I don't think it is possible, so I've been looking at minimizing the power requirements.
Cement ball mills are less than 1% efficiency.
Having done two postdocs in the field i can tell its not progressing very fast...
If it's cement, you presumably can't count 'construction' as it would be double-counted. Do you count an iPhone just during production? Or do you include shipping? If you include shipping, you can't have 'cargo ships' as it's own category.
We don't need to eliminate categories, we just need to be clever in the way we present data. For example, there's nothing particularly difficult to understand in the statement "Cement is responsible for 8% of the world's CO2 emissions, half of which is from transportation, 1/3 of which is from cargo ships." If we likewise break down each category into its major sub-components, the sub-components can be recombined in different ways to produce a lot of interesting and actionable data. Having several charts side-by-side is much better than fighting over a single chart that doesn't add up to 100%.
Concrete might look very different in 25-50 years.
True more like it looked in 150 BC:
Let’s say we take cement out or drastically reduce it. Where does co2 sit in increased consumption of viable alternatives.
Does this not cancel out the effect of making the cement in the first place? And if not, why not?
Would love to know if anyone has a good understanding.
A largely overlooked issue with the idea of concrete absorbing CO2 is exposed surface area. Imagine a hydro dam, one side is saturated with water, the other side is air. The dam is also usually quite thick, several meters to hundreds of meters. That really limits the available absorption surface especially considering the ratio of surface area to volume. Concrete foundations, epoxy coated parkades, even painted surfaces start to drastically reduce the possibility of CO2 being absorbed.
Think of concrete like a membrane or a sponge. The thicker the membrane you want to pass a fluid through, the higher the pressure you would require. So using our pressure as atmospheric, getting a high depth of CO2 absorption requires a well connected pore structure, and a long time frame.
Add to this membrane metaphor the issue of size. We design concrete structures to prevent fluid transfer, especially hydro dams! H2O is a smaller molecule than CO2, and the static pressure on the ‘wet’ side of a hydro dam increases 1 atmosphere every 10m.
As concrete sets and gains strength, its porosity decreases. This process happens rapidly in the first few days, and only ever stops when the cement runs out of free water to absorb. CO2 absorption depth is a pretty common test when evaluating a structure for rehabilitation purposes (carbonation dept testing) as CO2 will mess with the concrete PH and corrode reinforcing steel which (depending on many factors) can be as shallow as 5cm from the concrete surface. I’ve seen structures with up to 5cm of depth, but that is outside of the norm. 1-2cm of CO2 absorption depth for a structure from the 50’s is pretty common in my area.
Modern concrete, through many different means, has a highly disconnected pore structure (compared to the concrete of the 50’s). New concrete, is designed to reduce any type of fluid transfer especially after the first few days of curing. This will reduce the depth of CO2 absorption further.
So bringing this all back together, consider the absorption depth of 2cm, a structure with minimal exposed surface area, and some sort of coating or cladding… and you very quickly realize that you are not going to be off setting CO2 production outputs by any significant margin, and its not in your best interests either.
And agreed that surface area would effect the rate of absorption. I understand it can take hundreds of years for concrete to fully harden, which I could see being effected surface area and ability of the material to breath.
I have to wonder why we are still looking for new ways to employ Portland cement at this point, over alternatives. You can, I’m told, reduce the footprint of clinker a bit with fly ash, but you get that mostly from coal, so it’s splitting the “savings” with an equally problematic cousin, and at any rate that supply should be in steady decline now, although I guess we discovered the Tennessee Valley Authority has stockpiles of the stuff when they lost one of them a decade or two ago.
I am not an American but I am not sure I have even seen a paver made from brick now that I think about it. I suspect the larger a brick is, the more chance of cracking.
So if it makes you feel any better, you probably would not find one in New Zealand either.
But I don't think any national chains carry them anymore.
90% of landfill debris is from demolition.
We need more renovation instead of new construction.
From page 128 of
There’s a Wikipedia page on the subject but little of it sounds familiar, and those bits have no citations.
Not quite the same as your opener that claimed that it's 90% of all debris.
The long term geobiological trend is for C02 to decrease through absorption by weathering rocks and burial of biogenic limestone in subduction zones. C02 was thought to be as much 50% early Earth. Then a percent or two in early Phanerozoic 400 million years ago. And natural about .025% in the current ice age.