Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

bbc.com

Post reply on HN
Print view View original

121–130 of 158 posts

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

#121

Post by barumi »

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.

> Do we want 100 year old buildings?

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.

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

#122

Post by Gustomaximus »

manfredo wrote: post #26
aero-glide wrote: post #4

Very interesting, didn't expect it to be that high. Another thing I came across recently : The fashion industry is responsible for 10 % of annual global carbon emissions. Source : https://www.worldbank.org/en/news/feature/2019/09/23/costo-m...

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…

Also an interesting study compared what people bought who didn't buy meat, as vegetarian diet tends to be cheaper too. This brought the carbon difference to within 2%. I can't find it but think it was from Swedish researchers.

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

#123

Post by s0rce »

hinkley wrote: post #32

I was looking for brick pavers recently and was having quite a time locating actual bricks instead of cement pavers colored badly and textured worse to look vaguely like bricks to nobody sober during daylight hours. I can only assume their target audience is a drunken man, at night, in a rainstorm. I have to wonder why we are still looking for new ways to employ Portland cement at this point, over alternatives. You c…

You can also supplement with iron slag cement and silica fume from iron and silicon production, respectively. Those are probably not going away.

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

#124

Post by danans »

mrweasel wrote: post #90
jmiskovic wrote: post #70

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. 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.

>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…

> The fact that a house needs to be pressure tested seems insane.

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.

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

#125

Post by filoeleven »

vixen99 wrote: post #61
akira2501 wrote: post #12

Earlier quoted context omitted.

That was my biggest take away from the Biosphere documentary, as it was the concrete used in it's construction that eventually led to the abundance of CO2 and lack of O2 in that closed system. We'll clearly have to use something else for building moon bases.

Sorry for the tangential drift but it's ubiquitous now. I guess those boring grammar pedants should finally give up. The totally meaningless and incorrect apostrophe in it's (unless it indicates an abbreviation) has gone viral. You can even find it in headlines in newspapers. Odd really that many of us go to the trouble of adding a pointless character intent as we are on writing correct English. I think we should kee…

I suspect a lot of the rise is fueled by autocorrupt on smartphones. It changes every damn time on iPhone, and it takes effort to get it with no apostrophe.

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

#126

Post by magicalhippo »

jillesvangurp wrote: post #66
ehou wrote: post #23

The article doesn't mention one alternative: CLT (cross laminated timber) as a building material for houses and flats. See https://www.bbc.com/future/article/20190717-climate-change-w... for example. 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.

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...

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

#128

Post by refurb »

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…

Renovate every 20 years? There are plenty of wood houses that are hundreds of years old and have had minimal renovation to the wood frame.

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

#129

Post by [deleted] »

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.

[deleted]

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

#130

Post by NineStarPoint »

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…

On the east coast I’ve lived in plenty of wood houses that were built in the mid 1900s and just renovated every few decades. My last rental was even originally built in 1910. Well built wood frames can last for a long time.
Post reply on HN