Hope your client is aware, for the credit he needs an independent, third-party firm to review the building to confirm the energy savings and potential tax deduction. Also , for businesses that are seeking 179D based on work performed on government-owned buildings, these companies are required to secure an allocation letter that allows the government entity to transfer the benefit to the taxpayer. I know this doesn't answer your Question, but maybe @TaxGuyBill  will help out.