This is super interesting to me because I do LCA and my husband works for a general contractor and we have discussions about topics like this around the dinner table all the time!
Baselines are definitely important and in doing the LCA, it’s good to do a hot-spot analysis to determine what’s driving the impacts and balance that with what your company has control over to reduce and what is cost effective. If it’s just for internal use, then you don’t need to take the results through critical review, but it could be good to have some guidance from an outside party if the results are going to drive decisions about business operations or spending.