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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)

#131

Post by BossingAround »

teruakohatu wrote: post #65
BossingAround wrote: post #29

Earlier quoted context omitted.

> High end selvedge jeans might run a couple hundred bucks, but they will last a decade. 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.

You see the British aristocracy wearing 30+ year old shoes that look as good or better than they did when they were new. 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.

We're not talking extreme-luxury clothing here though. We're talking Ralph Lauren vs H&M, or something similar. What the British aristocracy wears is probably hand-made stuff by world-class artisans. What Ralph Lauren makes is mass produced in either Europe or China, so it's a much closer comparison to H&M (not to mention still within the reach of an average person in a rich country)

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

#132

Post by jakear »

leetcrew wrote: post #107
mrweasel wrote: post #90

Earlier quoted context omitted.

>Do we want 100 year old buildings? 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 pu…

> 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? 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 w…

> open the windows if you prefer fresh air, or you can enjoy much more efficient AC/heat

How can something powered by electricity/natural gas/etc be more efficient than simply opening the windows and letting Mother Nature do the work?

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

#133

Post by toomuchtodo »

immmmmm wrote: post #120

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...

Is there any reason these facilities can’t source power using renewables PPAs?

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

#134

Post by krab »

throw0101a wrote: post #114
nom wrote: post #96

Earlier quoted context omitted.

> 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 cutti…

Why would you remove concrete and masonry every 20 years? I don't have much experience with wooden houses, so I don't know if it's the case there.

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.

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

#135

Post by novok »

jmiskovic wrote: post #70
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…

Do we want 100 year old buildings? I don't think we can predict the needs of building even 20 years into the future. City layout could change drastically. Monumental buildings should last a long time, but not every structure. 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.

I think we do, if we design them properly in the first place. For example, in 11 years the empire state building will be 100 years old, and its still an very useful and beautiful building. I think as long as you design a building to use something like conduits, you can update the wiring, plumbing, hvac, elevators, etc over time and it can continue to be useful for centuries.

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

#136

Post by frank2 »

magicalhippo wrote: post #126
jillesvangurp wrote: post #66

Earlier quoted context omitted.

Yes. And better than that using this at scale is going to require massively scaling up wood production (i.e. forestry). This too will help with capturing a lot of co2 in the soil. A lot of countries would end up restoring farm land to production forests and probably end up using sustainable practices for this. For those unfamiliar with CLT, this is a high tech building material suitable for making e.g. sky scrapers o…

At least per 2019 when it was opened Mjøstårnet[1] is the world's tallest timber building. It's only 85.4m (218ft) though[2]. There's also a report[3] about a glulam burn test, something I was quite curious about. [1]: https://www.moelven.com/mjostarnet/ [2]: https://en.wikipedia.org/wiki/Mj%C3%B8st%C3%A5rnet [3]: https://www.moelven.com/mjostarnet/glulam-can-withstand-a-bu...

The wikipedia page you link to says it has a concrete core.

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

#137

Post by lostlogin »

decasteve wrote: post #97
nom wrote: post #96

Earlier quoted context omitted.

> 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…

You are not wrong. However, houses could still be built from wood like the 500 year old houses and churches made with actual timbers. Timber framed houses would use a lot less wood in the long run due to less waste and greater longevity (especially when coupled with bricks and concrete). Milling large trees down to 2x4s and coupling it to drywall to build homes that don't last is a travesty.

What are you counting as a house that hasn’t lasted? 50 years? 100? The house I am in was built in the 1940’s by the state as an employment and housing scheme for returned servicemen post WW2. It’s wood framed and has a fair few years of life left if cared for.

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.

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

#138

Post by jgamman »

loourr wrote: post #113
concguy wrote: post #109

Earlier quoted context omitted.

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…

the crystals that form and bind the aggregate together are a hydrolysis reaction (water using). Water is the main reactant not CO2.

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

#139

Post by magicalhippo »

frank2 wrote: post #136
magicalhippo wrote: post #126

Earlier quoted context omitted.

At least per 2019 when it was opened Mjøstårnet[1] is the world's tallest timber building. It's only 85.4m (218ft) though[2]. There's also a report[3] about a glulam burn test, something I was quite curious about. [1]: https://www.moelven.com/mjostarnet/ [2]: https://en.wikipedia.org/wiki/Mj%C3%B8st%C3%A5rnet [3]: https://www.moelven.com/mjostarnet/glulam-can-withstand-a-bu...

The wikipedia page you link to says it has a concrete core.

I think you misread? The concrete core is in reference to a building in Austria.

"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."

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

#140

Post by leetcrew »

jakear wrote: post #132
leetcrew wrote: post #107

Earlier quoted context omitted.

> 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? 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 w…

> open the windows if you prefer fresh air, or you can enjoy much more efficient AC/heat How can something powered by electricity/natural gas/etc be more efficient than simply opening the windows and letting Mother Nature do the work?

poor wording. I mean more efficient than ac/heat in a leaky house.
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