Any tips on Whole Life Carbon Comparisons for Retrofit vs New Build?

I’ve been getting more questions from real estate owners/developers about how to calculate and compare the whole life carbon emissions implications for new construction versus retrofit projects. E.g, Is there a case in which existing building is so inefficient that is it a better life cycle choice to tear down and build new? I know about the 2Build or Not 2Build tool in development, but would love tips on any other resources/studies out there. Thank you!

Tagging @lstrain here- he’s building an easy calculator called 2 Build or not 2 Build that helps developers answer this exact question.