3 ms·

> Insulation does matter, but American insulation is also pretty strange- it is all rated by R value, which is only meaningful if you have a really good airtigh

> Insulation does matter, but American insulation is also pretty strange- it is all rated by R value, which is only meaningful if you have a really good airtight seal. You're not wrong, but IMHO the two should be handled separately. The fact that airtightness has been less stringent in the US is mostly an accident of history, which is being improved with recent building codes. It's just that in the past it was easy for people to simply buy some fluffy stuff and stuff it into the walls: doing blower door tests is a lot more complicated. Building science has also progressed quite rapidly in the last 2-3 decades, and we now 'know better' in many areas than in the past. > Aerated concrete doesn't have that issue, because the concrete cells are closed and don't draft. If you end up with a poorly fitted window or 50+ mph winds, it doesn't let air through. First: what's the carbon footprint of concrete? What is footprint of wood framing? Not letting air through (in or out) is actually what you want. The structures of buildings should not pass any air at all ideally, and all air exchanges should be done primarily via mechanical means: * https://www.youtube.com/watch?v=CIcrXut_EFA https://www.youtube.com/watch?v=CIcrXut_EFA

zdragnar 5y ago
I should edit that- I meant that even with a poorly fitted window or 50+ mile winds, the closed cell nature of the concrete doesn't let air circulate through it, while fiberglass does. Such is, my point was that foam boards and concrete are compared to blown / rolled fiberglass, even though the fiberglass has more failure modes for insulating. A poorly fitted window will seriously compromise the R value of the surrounding fiberglass. As for the carbon footprint of cement, solid is pretty high, foam not so much. I don't know about commercial stuff, but most DIY'ers seem to use a little under 100 lbs portland cement to make a 55 gallon barrel's worth once the foam is mixed in. Rough math puts a 55 gallon barrel of concrete at about 1000 pounds. Edit: I just realized that 10% seems low, so what I saw may have used a 55 gallon barrel but not completely filled it. In any case, depending on the structural integrity that you need, the weight reduction (and therefore carbon footprint from curing) is significantly reduced.
icoder 5y ago
We're living in an airtight, concrete, triple glazed house in europe with mechanical ventilation with heat exchange, plus heat pump on a ground source for heating amd (moderate) cooling. It's amazing, temperature is great 24/7 year round. Having said that, your point about footprint holds and building with wood is coming 'back' here especially because of that, using cross laminated timber from sustainable forests.
glogla 5y ago
> First: what's the carbon footprint of concrete? What is footprint of wood framing? Carbon footprint of wood framing is terrible, because its mostly made of engineered wood with a lot of oil in it.
- throw0101a 5y ago
  > mostly made of engineered wood with a lot of oil in it. [citation needed] Certainly LVL and LSL products are more processed, as is OSB, but those have the advantage of using 'off cuts' so they can use up some of raw materials that might otherwise be thrown out. Even with all that processing I find it hard to believe that it would be worse than concrete, given the amount of (fossil fuel?) energy needed for cement kilns and other things. * https://en.wikipedia.org/wiki/Environmental_impact_of_concrete https://en.wikipedia.org/wiki/Environmental_impact_of_concre...
- AtlasBarfed 5y ago
  ... is the oil burned?

zdragnar 5y ago

I should edit that- I meant that even with a poorly fitted window or 50+ mile winds, the closed cell nature of the concrete doesn't let air circulate through it, while fiberglass does. Such is, my point was that foam boards and concrete are compared to blown / rolled fiberglass, even though the fiberglass has more failure modes for insulating. A poorly fitted window will seriously compromise the R value of the surrounding fiberglass. As for the carbon footprint of cement, solid is pretty high, foam not so much. I don't know about commercial stuff, but most DIY'ers seem to use a little under 100 lbs portland cement to make a 55 gallon barrel's worth once the foam is mixed in. Rough math puts a 55 gallon barrel of concrete at about 1000 pounds. Edit: I just realized that 10% seems low, so what I saw may have used a 55 gallon barrel but not completely filled it. In any case, depending on the structural integrity that you need, the weight reduction (and therefore carbon footprint from curing) is significantly reduced.

icoder 5y ago

We're living in an airtight, concrete, triple glazed house in europe with mechanical ventilation with heat exchange, plus heat pump on a ground source for heating amd (moderate) cooling. It's amazing, temperature is great 24/7 year round. Having said that, your point about footprint holds and building with wood is coming 'back' here especially because of that, using cross laminated timber from sustainable forests.

glogla 5y ago

> First: what's the carbon footprint of concrete? What is footprint of wood framing? Carbon footprint of wood framing is terrible, because its mostly made of engineered wood with a lot of oil in it.

throw0101a 5y ago
> mostly made of engineered wood with a lot of oil in it. [citation needed] Certainly LVL and LSL products are more processed, as is OSB, but those have the advantage of using 'off cuts' so they can use up some of raw materials that might otherwise be thrown out. Even with all that processing I find it hard to believe that it would be worse than concrete, given the amount of (fossil fuel?) energy needed for cement kilns and other things. * https://en.wikipedia.org/wiki/Environmental_impact_of_concrete https://en.wikipedia.org/wiki/Environmental_impact_of_concre...
AtlasBarfed 5y ago
... is the oil burned?