I'm working on a project that has lots of demolition phases, because it depends on the expropriation of several buildings.
The first demolition occurred in 2011, when the project wasn't yet seeking LEED certification, and since then the records of this demolition phase were lost.
The second demolition phase occurred this year (2015) and demonstrated almost 95% of diversion, and the following phases (approximately 2), intend to seek the same diversion rate.

My question is: how do we account for the demolition waste generated in 2011? We're considering the following option, and would like to hear your thoughts:
- Estimate the volume of the demolition based on pictures and tipology of building and consider all of it was destined to a landfill.
And for the rest of the waste from all the other demolition phases we will keep the proper records and consider all of them in the calculations in order to achieve an average of at least 50% diversion.