Scott,
Are you looking at static emission numbers comparing embodied vs operational emissions? If so, this isn’t taking into account the time value of those emissions. When comparing embodied and operational emissions - or really, any emissions over a time scale - looking at ton-years may be a more relevant metric for the atmospheric impact of those emissions across your timeframe. For example, 1000 kg CO2e emitted from A1-A5 activities persists in the atmosphere (mostly, with some decay, depending on the chemical), continuing to act as greenhouse gasses throughout the 10 year window. Ignoring decay and simplifying for the sake of example, at the end of that ten year period, the embodied emissions will equal 10 ton-years. I expect this may change the math in your analysis.
I’m not a dynamic LCA expert by any means, so if someone out there wants to push back or clarify this, please jump in. My understanding is that when emissions are released and how long they act as greenhouse gasses in the atmosphere is critically important for emissions accounting over time, and this is of particular importance when valuing the reduction potential of carbon storing materials and comparing embodied and operational emissions that occur over time.
Cheers,
Jacob