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Cement is the source of 8% of the world's CO2 emissions (2018)

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Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#111

Post by catawbasam »

nom wrote: post #96
throw0101a wrote: post #93

Earlier quoted context omitted.

> Do we want 100 year old buildings? I don't think we can predict the needs of building even 20 years into the future. 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…

> Buildings are just boxes for people which keep the cold/heat/moisture at a comfortable level. 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…

Properly maintained wood houses are good for 100 years. My house is 70 years old. It required insulation and electrical upgrades, mostly diy, but is otherwise fine. Also, the wood is a carbon sink, vs masonry being a carbon source.

Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#112

Post by catawbasam »

tinco wrote: post #59
austhrow743 wrote: post #45

Earlier quoted context omitted.

I’ve always wondered how much standardisation there is in reporting these types of numbers, particularly with regard to countries, albeit not enough to actually look in to it. 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 do…

It goes to China, because it is the one that can change it. But that's when you're looking at the output of countries. What you could also do is look at the output of individual persons, and then you could more easily attribute the CO2 to the American. Sustainable energy without the hot air does this, it's a great book though I've heard it's somewhat outdated now.

The analytic approach is great, but the numbers are very out of date.

Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#113

Post by loourr »

concguy wrote: post #109
loourr wrote: post #102

One question I've had about cement being a major source of CO2 emissions that I haven't seen addressed anywhere is that my understanding is as cement cures it does so by absorbing CO2 which is what turns it into rock. 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.

While concrete does absorb CO2 there is a large misconception that it can absorb as much as is output during production. In reality any concrete worth its cost can only absorb a very small fraction of the production output. 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 qu…

Thanks for the explanation, those are good points. Though wouldn't the interior concrete not harden if it wasn't able to absorb CO2, since my understanding is that's fundamental to the hardening process?

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.

Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#114

Post by throw0101a »

nom wrote: post #96
throw0101a wrote: post #93

Earlier quoted context omitted.

> Do we want 100 year old buildings? I don't think we can predict the needs of building even 20 years into the future. 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…

> Buildings are just boxes for people which keep the cold/heat/moisture at a comfortable level. 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…

> 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?

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:

* https://www.buildingscience.com/documents/insights/bsi-001-t...

And floor trusses to reduce/eliminate internal load-bearing walls:

* https://www.youtube.com/watch?v=ysT3zXkFGB8

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?

* https://en.wikipedia.org/wiki/Lath_and_plaster

Some growth in popularity for wood in Europe; some Swiss examples:

* https://www.youtube.com/watch?v=RlplalGNfFM

* https://www.youtube.com/watch?v=4j_UjIshzMc

Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#115

Post by kube-system »

nom wrote: post #96
throw0101a wrote: post #93

Earlier quoted context omitted.

> Do we want 100 year old buildings? I don't think we can predict the needs of building even 20 years into the future. 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…

> Buildings are just boxes for people which keep the cold/heat/moisture at a comfortable level. 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…

Wood is cheaper in North America than it is over there. Also it has some advantages, like being easy and cheap to work with, safer in areas with seismic activity, and it’s renewable.

Wood structures have no issues lasting 100+ years as long as they’re protected from water and termite damage.

Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#116

Post by ianstormtaylor »

austhrow743 wrote: post #45
manfredo wrote: post #26

Earlier quoted context omitted.

Statistics on how much CO2 something emits can vary wildly. For instance, meat consumption has high CO2 emissions when you include the CO2 emitted by transporting grain to feed animals. But most typical studies would include that under emissions due to transportation. Hence why you can have some studies claiming meat accounts for a double-digit percentage of emissions while others claim that all agriculture contribut…

I’ve always wondered how much standardisation there is in reporting these types of numbers, particularly with regard to countries, albeit not enough to actually look in to it. 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 do…

It depends on what type of accounting is being used. If it’s a production-based accounting then they’ll be attributed to China. But if it’s a bottom-up, consumption-based accounting then they’ll be attributed to the consumer in the United States.

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.

Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#117

Post by minerjoe »

rowanG077 wrote: post #95
darawk wrote: post #16

Earlier quoted context omitted.

The overwhelming majority of clothing produced is totally unnecessary. The fast fashion industry produces an insane amount of clothing, way beyond what is necessary for utilitarian purposes. I don't doubt that it causes that much CO2 emission, especially if you factor in the shipping cost from the places that manufacture it.

I believe this is generally true of any utility. We can all live of soylent or something instead of moving around foods that spoil easily for example. We could all also live in large concrete block where everyone has a small room and houses don't exist. All of that would be hugely more efficient but I doubt you or many other people would like that.

A bit of an excluded middle - soylent or what we have now, a massivly wasteful and inneficient food system. I, and many others, would argue that localization and diversification of the food system is the missing middle here.

Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#119

Post by barumi »

shortercode wrote: post #68

The largest issue with concrete is that we misuse it. As a building material it has great thermal mass ( aiding temperature stability ) and longevity. But all too often buildings are poorly designed for renovation, and hence end up being torn down after a couple of decades. A small fraction of the useful lifetime of the structure. Any building using concrete for a structure should be aiming to last at least 100 years…

> Any building using concrete for a structure should be aiming to last at least 100 years.

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.

Re: Cement is the source of 8% of the world's CO2 emissions (2018)

#120

Post by immmmmm »

Also the power needed to grind clinker down to powder is huge, overall comminution (grinding) industrial processes are among the biggest electricity consumer in the world.

Cement ball mills are less than 1% efficiency.

https://en.wikipedia.org/wiki/Cement_mill

Having done two postdocs in the field i can tell its not progressing very fast...

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