I was in the weeds on an LCA for a T.I. project where we were comparing generic (finish) materials to specific products that were installed per submittals. In comparing a Tally baseline run to a proposed run updated with EPD data, I found what I think is a pretty big error in the acidification potential background data for Mohawk Ecoflex ICT nylon carpet tiles, which I’ve been using as the default US-manufactured commercial carpet tile.
Back-calculating Tally’s A1-A3 emission factor in kg SO2e/m2, I get a whopping 2.74, compared to the 0.040 emission factor I pulled directly from the EPD listed as the LCI source. The Tally factor looks closer to the acidification potential quoted in mol H±eq in the EPD.
Has anyone run into this? I may be overlooking something…but wanted to raise this PSA in case others out there have been sounding the alarm on carpet’s acidification potential based on Tally data!
I just did a test run and got the same numbers. For those interested, the A1-A3 impacts from Tally for a m2 of carpet are as follows:
|Acidification Potential Total (kgSO2eq)
||Eutrophication Potential Total (kgNeq)
||Global Warming Potential Total (kgCO2eq)
||Ozone Depletion Potential Total (CFC-11eq)
||Smog Formation Potential Total (kgO3eq)
||Primary Energy Demand Total (MJ)
||Non-renewable Energy Demand Total (MJ)
||Renewable Energy Demand Total (MJ)
||Mass Total (kg)
I’m inclined to agree with your assumption after looking at the EPD. The numbers roughly match up with the h+ moles numbers, and the only conversion i could find between h+ moles and kgSO2 was a similar order of magnitude (i got around .08. take that with a metric ton of salt)
One other thing I noticed - the ecoflex epd is very old (2013) and expired in 2018. I couldn’t find an updated version. It looks like it was using an older version of TRACI as well, as it looks like the next version TRACI 2.1 changed from h+moles eq to kgSO2eq. (Version 4.2 Build 02 | Life Cycle Assessment Software). All of this makes me really question the data quality.
Doesn’t seem like there’s a good alternative either. The commercial carpet options all come form a European EPD that expired in 2021…
Switching in actual carpet EPDs can be done by using the raw tally data take off for area and replacing numbers with the EPD numbers, but I don’t know what should be used for a baseline number. Anyone have a north american industry standard nylon carpet epd?
Thanks Justin. That’s a great point about the data source…I’ve been tracking some of the other “problematic” background data:
I wonder if there are plans to update the data sourcing, or if we are waiting for TallyCAT magic In the meantime, I’m thinking about establishing a standard post-processing workflow with industry-average EPDs for the US where available…plywood, vinyl flooring, GWB all have good data to sub…
Thanks for sharing that - I’d be happy to join in the post processing discussion. Hopefully, as you said, we only have to do this until TallyCAT comes out.
Not to make you learn new software, but have you considered using OneClick LCA to compare results? To be honest, I am not super familiar with Tally and been using OneClick LCA to run our LCAs. It seems a bit more transparent in being able to manually input your quantities and map materials. Just a thought.