Accounting For EC During B1-B7 Use Stage

I have been randomly polling peeps on where we account for EC within the LCA stages for actual building material replacement that has a life expectancy of less than 60 years? The most common response seems to be, B1-B7 Use Stage as opposed to A1-A3 Product Stage. The B1-B7 Use Stage response seems to be opposed to Product Category Rules yet that is the most common response from peeps that regularly endeavor in LCA discussions? Your thoughts and input are greatly appreciated.