Embodied Carbon

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    Gustavo Diez-Presilla

    Embodied carbon or embodied energy?

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    Danielle Aspitz (Edited )

    Sorry, yes the question uses the term "embodied energy" - had thought the terms were interchangeable, but it is a good point, there are some differences in definition. 

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    Gang Chen

    There are some content on green buildings for ARE exams, but they mostly focus on heat island effects, solar, building orientation, albedo, etc.

    Gang Chen, Author, AIA, LEED AP BD+C (GreenExamEducation.com)

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    Rebekka O'Melia

    No, that's not a topic I'd study for this exam.

    Any building material that is local to the area where the project is being built is going to have less environmental impact. That being said, I think that's an oddly specific question and definitely NOT part of PA's material.

    Hope this helps!

    Rebekka O'Melia, Registered Architect, NCARB, B. Arch, M. Ed, Step UP, Step UP ARE 5.0 Courses

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    Christopher Hopstock

    Hi Danielle,

    Embodied energy of materials is covered in a few of the references listed in the ARE Handbook, for example in Building Construction Illustrated (page 741) and MEEB (table 2.4).  We often hear from candidates that they saw questions on their exam that they viewed as 'out of left field' so we try to mimic that experience on our practice exams, while still only using information that can be found in the official NCARB resources.

    That said, I wouldn't study by trying to memorize these tables - if a question like this is on your exam, it will probably be only one question and it's unlikely that the exact materials you studied will be the topic of the question.  I'd focus on understanding, in general terms, which materials have higher embodied energies and which have lower.

    I hope this was helpful and good luck on your next exam!

    Chris Hopstock RA
    Black Spectacles
    ARE Community

     

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    Michael Ermann

    Yeah, it does seem a little suspect that concrete block (cement) would have less embodied energy than brick (clay). The University of Bath data backs that claim up, though. Maybe your source looked it up on Wikipedia, because it's there too under "embodied energy of materials."

    I'm not sure that data includes the insane amount of carbon that concrete spews out when CURING. I think it only includes the manufacture and only focuses on energy and not carbon. (read on). This is the distinction some others were making above about carbon vs energy. Below is a list that will help:

    Materials with high embodied energy

     

    Manufactured with high heat:

    Ceramics

    Glass

    Stainless or galvanized steel

    Concrete (but, because of its weight, can look on tables like it has low embodied energy when measured on a per-kilogram basis). Concrete is responsible for 8% of the total carbon humans emit into the atmosphere. If the cement industry were a nation, it would be the third-largest carbon emitter behind only China and the US.

     

    Manufactured with intense chemical processes and petrochemical use:

    Epoxies/Resins/Formaldehyde/many adhesives

    Paints and stains

    Foam insulation (polystyrene, spray-foams, polyisocyanurate)

    Plastics/Vinyl/PVC/melamine/polycarbonate

    Engineered wood products (MDF, Glue-lam)

     

    Manufactured with intense mining processes:

    Copper

    Aluminum

    Stone

     

    Transported from far away:

    Anything heavy and brought far (like countertop granite from India when you live near a granite mine)

     

    Materials with low embodied energy

    Cellulose and glass fiber insulation

    Wood (depends on what powers the kiln and whether you include the loss of the carbon-removal capabilities of the tree that was cut down)

    Gypsum board and plaster

    Rammed earth

    This topic is 100% in-play on the exams. In about 2014 NCARB scrambled to incorporate "sustainability" into the AREs . . . In those early years, like so many architects did, they over-focused on materials. The smart people who study sustainability tell us that, in most cases, operations (i.e. energy use) is by FAR the better task to tackle to reduce carbon, relative to materiality. . . I think that NCARB has since got the message (I, for one, have talked with them about this issue), but those older test items presumably still remain in circulation in the test item bank (and reducing the embodied energy of materials isn't a bad thing. . . it's just that if your ship is sinking and taking in water fast, hanging the wet towels off the balcony rails won't dry the ship out effectively).

    I covered embodied energy in a video here.

    *note that a given manufacturer can easily greenwash here by measuring embodied energy per weight (concrete looks better because it is heavy), per square foot (vinyl looks better because it is thin), or per volume (foam insulations look better because they’re big). The biggest greenwash comes from the concrete industry because their data usually fail to account for the insane amount of carbon released as cement cures and oodles of CO2 enters the atmosphere through that process. I don’t know that NCARB knows this yet (maybe word will get to them through this post). If you see conflicting data, it’s often that concrete comes out looking like the best low-carbon option (measured by embodied energy by weight but not accounting for the equivalent embodied energy from off-gassing during curing) or the worst (measured by equivalent embodied energy—including curing—by square foot of surface area). In fact, when I, while writing this, google “embodied energy by material” now, and then click on the images tab to see the most popular graphs your first graph has concrete as the worst offender and the second one has concrete as the panacea to solve our carbon problems. (The first one is right).   The most legit data I’ve found is from the University of Bath and can be accessed here. —Michael Erman

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    Christopher Hopstock

    Thanks for bringing up the Wikipedia article Michael - I just checked and it's actually the same chart that is in MEEB (table 2.4), which is the reference that we list for this question.  

    Chris Hopstock RA
    Black Spectacles
    ARE Community

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