[morsch]

> tho there's a lot more to the project that probably goes in the other direction

I mean, this is obviously why this is just a fun math exercise and not much else. Building an airport, even if you build part of it out of wood, is not net carbon-negative.

[pmayrgundter]

Just finished the full edit.. check it out. If the full airport is made out of wood, seems like it's getting towards plausible, or at least not obviously wrong

Most uncertainty is how much mass the ceiling is compared to rest of airport. Maybe it's more like 1/10th. Hmm

[morsch]

Apparently they used 4.4 million cubic yards of concrete during the construction of Denver airport around 1993.

That's 3.364×10^6 m3, 1 m3 of concrete weighs 2.4 tonnes (I'm sure it varies), so roughly 8 million tonnes of concrete.

https://www.concreteconstruction.net/_view-object?id=0000015...

I'm not convinced the wood used in the Portland airport project is net negative in itself, once you factor in the emissions of harvesting, processing and transporting it. I.o.w. leaving the ugly old roof in place would probably have been better, in terms of CO2eq emitted.

[pmayrgundter]

I found a more authoritative reference, from the Institute of Structural Engineers, which appears to be a major international organization [ISE].

The Embodied Carbon figure they use is 1.64kgCO2/kg timber as a rule of thumb [ISE-EC], and agrees with what I posted above

For processing that yields built lumber, they account in stages, with % CO2 emissions added:

A1) Raw Material Extraction, 20-25% A2) Transport to Facility, 8-10% A3) Manufacture, 5-10% A4) Transport to Site, 50-55% A5) Construction, 10-15%

A1 to A3 reduce sequestration by 0.28, for a net of 1.36. They then say A4&5 account for 1.5x more emissions than A1-3, so .42kg total factor, for a net sequestration of 1.22kgCO2/kgBuiltLumber. They separate these as the transport is the largest variable between projects.

These figures are from Austria to UK. From the reporting, the PDX project is using mostly local wood.

So I think they're getting a net sequestration for the roof project.

It's really interesting that building with wood has this major sequestration factor. It'd be really something if we could build our way out of the environmental crisis just by switching to wood! :)

[ISE] https://en.wikipedia.org/wiki/Institution_of_Structural_Engi...

[ISE-EC] https://www.istructe.org/IStructE/media/Public/Resources/ARU..., p17: "The amount of carbon sequestered can be assumed as -1.64kgCOe per kg of timber when product-specific data is not available". I take the e to be emission, so a negative is a sequestration.

[morsch]

The e is short for equivalent.

https://chancerylaneproject.org/glossary/carbon-dioxide-equi...

[pmayrgundter]

thanks. Also forgot to note size difference between those airports.. DEN is #4 in the US with 38M passenger boardings/year, PDX #33 with 8M. So maybe 4x larger

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