@jkitchin thanks! after seeing your numbers in EC3 I have done the same but applying the Spanish numbers. It is great to play with the numbers, and it shows how different can be the results looking at specific EPD’s, or using the 80th percentile values (even global or by countries). The conclusion I take from this is that sometimes using the specific EPD of the material used in the building can be worst that using the 80th percentile. ¿why? because there are lots of assumptions behind the different EPDs. We may think that the more accurate we are (by using the EPD of the material) the most accurate results we will get. But in this case, it doesn’t seem the case.
Another interesting issue I have found comparing the results of the same EGOIN CLT EPD in EC3 to the same EPD in OneClick is that from the same impact category A1-A3, the results of GWP are different, whereas the results of the other environmental impacts (acidification, eutrophication, etc) are the same! ¿can there be a problem of transcription? I have already asked to OneClick to double check.
Regarding your last comment, we have worked with the structural engineer and they have said that the difference between the mass of concrete and CLT structures might reduce the foundation loads, but not that much. It is true that we could work on that to compare, but for now we will not take it into account. I prefer to keep as few variables as possible unless they change the results a lot. Regarding the structure of the basement, another conclusion that we have noticed is that in addition to the optimisation that the engineer could do (which could be a lot), in Spain (for the building type we are working with) the law obliges us to include parking for cars in most cases. This forces the project to build from 1 to 3 floors below grade, with the associated retaining wall and load-bearing mass. We will use reinforced concrete for those bellow grade structure, and this amount of reinforced concrete could be a lot if compared with the concrete above grade structure, which makes the reduction of concrete less important in %. We have found here that will be necessary to start working with low embedded concrete carbon. The architecture team also requested the city council for an exception of the norm, and they allowed us to construct less parking cars than usual, allowing the project to include just one floor bellow grade instead of two. This reduced a lot the amount of concrete, but we won’t include this as an strategy of reduction because the GFA won’t be comparable then.
Anyway… just to share! thanks for your feedback!