While we are getting up to speed on using OneClick LCA in our practice, most of our project LCAs are still in Tally, which currently has a more fixed database of materials. For Tally models where we want to show an improvement with the concrete mix, our work around in the past has been to look at the percent improvement of a submitted mix from the regional NRMCA baseline, and then reduce the 'Density or % Solid' from 100 to the amount which corresponds to the GWP reduction. I don't know if this adheres to the ISO methodology governing the softare exactly but it's the only way I know of to get Tally to represent EPD values that aren't covered in its database.
My question is, assuming this workaround to represent concrete is allowable by USGBC, would they allow the same method to be applied to other materials to represent improvements for product specific EPDs? i.e. interior and exterior materials, and other structural materials?
If we highlight these changes in the narrative, along with the Tally LCA reports, will that cover the documentation needed?
