Embodied carbon of cellulose insulation
I’m having a surprisingly difficult time finding some numbers for the embodied carbon in cellulose insulation.
Anyone have a good source for this info? I thought it would be but a google away, but I’m stumped! Maybe I’m just missing the secret search term.
Ideally, separating out with and without accounting for carbon sequestration would be great, but really anything is helpful.
ICE v3 doesn’t appear to list it ( http://www.circularecology.com/embodied-energy-and-carbon-footprint-database.html )
I wasn’t successful in finding the data behind the graphic here: https://materialspalette.org/insulation/
I did find reference to the embodied energy of cellulose being 0.45 MJ/kg (source: http://www.greenspec.co.uk/building-design/insulation-materials-thermal-properties/ ) but I’m not sure if there is a reasonable way to relate that to the embodied carbon.
Any help is much appreciated!
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While I’ve always hated the “energy=carbon” concept since it’s not really accurate, you might be able to get the info you’re looking for with a little bit of unit conversion. 0.45 MJ megajoules) works out to 0.125 kWh (kilowatt hours) since one joule is equivalent to one watt*second. So that means one kilowatt hour makes 8 kilograms of cellulose insulation using the info you have. If you can figure out what the energy source / fuel mix is of wherever your cellulose was manufactured, you can use that info to determine how much carbon containing fuel was used to produce each kWh and work out how much carbon was released to manufacture each kilogram of cellulose.
Keep in mind that a lot of cellulose insulation is made from primarily recycled materials too. Insulation is also somewhat unique in that it will result in energy savings over the typically pretty long life of a structure.
Bill
Thanks Bill,
If I just use the rough "energy=carbon" conversion, does this look like a reasonable list of the carbon costs of different energy sources to you? https://en.wikipedia.org/wiki/Life-cycle_greenhouse-gas_emissions_of_energy_sources
It depends on how “rough” is acceptable to you. The fuel mix used to produce electricity varies by region. Canada and the Pacific Northwest of the US are almost entirely hydroelectric. The Midwest is primarily coal, the northeast primary natural gas these days. Nuclear is scattered around. The ISO (independent system operator) websites provide nifty real-time displays of the percentages of each fuel used for electric generation in each of their respective operating regions. This is your most accurate info most likely.
You probably won’t be able to quantity everything since you won’t have all the details of any particular manufacturers production methods. You’d need to know where the plant is (for electric supply info), where the raw material is (to figure out transportation energy used), then the fuel used to get the product to wherever you need it. As Dana also points out, cellulose is made from primarily recycled materials, so the original forestry and paper making energy use doesn’t really count, but the energy used in the recycling process does.
This stuff rapidly gets complicated, and you’re unlikely ever be able to get super accurate. I’d try to get as close as you feel comfortable with, and know that you put more thinking into this than your neighbors did :-)
Bill
Brendan,
Have you seen this article?
https://www.greenbuildingadvisor.com/article/all-about-embodied-energy
Phius has a global warming calculator as well for insulation. I'll see if I can find it.
Rick, does that article list an embodied carbon number for cellulose (not just embodied energy, which I already have)?
I'm not currently a paid subscriber, but I'll happily pay the $15 to read the article if it's got the numbers I'm looking for. I'd just rather not resubscribe just to find out the article doesn't have the info I'm looking for!
Aha!
This link has a value: https://www.buildinggreen.com/news-article/avoiding-global-warming-impact-insulation
This lists the embodied carbon of dense-pack cellulose as 0.106 kgCO2/kg.
Part of the wide variation in estimates is about differences in accounting methods.
The manufacturing energy/carbon costs for cellulose insulation would NOT rightly carry the carbon burden of the pulp & paper making, since it is manufactured from reclaimed/recycled paper. (Nobody is cutting down trees and making paper with cellulose insulation as the targeted end product.) The processing & transportation carbon cost of converting scrap paper into insulation counts, as does the mining and chemical processing of the fire retardents.
When the pulp & paper manufacturing numbers are included it's a MUCH larger number, of course.
If looking at sustainably harvested wood feedstocks vs. soil carbon depletion from unsustainable woodlot management practices for papermaking it gets even wilder.
Suffice to say, there is no one good number to use, but in the grand scheme of things it's pretty low carb. At 2lbs density cellulose is in the same range as rock wool or fiberglass even when counting the paper-making carbon footprint & offering zero credit as sequestered carbon. But the error bars on all of it are pretty large.
If we care about GHG, lowering the carbon content of woodlot soil could plausibly be a positive thing. Less bio-matter left to natural decay processes means less methane.
And also less ability for trees and other plants to grow and sequester additional carbon so more of a negative than a positive I think. Intentional Depletion of soil nutrients isn’t very green.
Bill
Carbon isn't a key growth-limiting soil nutrient - N, P, K, H2O, pH, and soil texture have a lot more impact. The tree often dispenses carbon into the soil through both leaf litter and directly through coarse roots in order to induce certain symbiotic fungi ("fine roots") to harvest N, P, K, and H2O.
Are we robbing the soil of NPK? Yes, we are. But we've got crazy-cheap, crazy-effective mineral & industrial sources of NPK, to the point that the excess supply is destroying watersheds.
"Green" diverges from "GHG-fighting" at some point. Burning the world's forests in tightly sealed charcoal kilns and burying all the charcoal in an open pit mine or on the abyssal plain would very significantly fight GHG, but it contravenes traditional notions of "green".
Forests don't fix carbon in the forest floor indefinitely. Once they're mature, carbon content peaks and then levels off. Keeping forests in immature growth mode through periodic culling ("sustainable management") is the farthest thing from 'green' in that it's an ecological monoculture nightmare, but it may significantly assist us on the GHG front, particularly if methane emissions from anaerobic decomposition is even a modest carbon leakage from the system.
People talk about geoengineering and artificial carbon fixation as if you could make a carbon fixing box, when we have self-replicating ones literally growing on trees that would be three to six orders of magnitude cheaper to use.