Appropriate Aluminium and Steel Cladding/Roofing EPDs?

Materials
2

James,

Thanks for asking this question. We (Colorado Embodied Carbon Collaborative) are trying to set values like you are (although for life cycle stages A-D), and the metal cladding category is difficult to pin down.

I do have some comments for you:

Aluminum

  1. The kg/m2 you are using of 4 is too high. 2 - 2.5 kg/m2 is probably more appropriate. The CLF baseline for aluminum in the cladding & roofing category is 18.6 kgCO2e/m2. The 10.76 kgCO2e/m2 is for aluminum extrusions which have higher A3 emissions.
  2. I also doubt the Pac-Clad value of 3.8. Note the weight of 2.07 kg/m2.
  3. The MCA EPD has the weights of steel and aluminum switched, so the aluminum should be 2.77 kg/m2. The 18.3 kgCO2e/m2 seems about right at the 2.77 kg/m2.
  4. I would use 18 kgCO2e/m2 for A1-A3 and 15 kgCO2e/m2 for full life cycle.

Steel

  1. The CLF 2023 baseline should be 15.3 kgCO2e/m2 from the Cladding & Roofing section.
  2. The MCA weight should be 4.91 kg/m2, although the 15.1 (15.6?) kgCO2e/m2 is correct.
  3. The MBMA EPD from 4/1/2021 shows 12.33 kgCO2e/m2. I think the MBMA numbers are low.
  4. I would use 15.3 kgCO2e/m2 for A1-A3, and 10 kgCO2e/m2 for A-D.

Bob

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