My law partner, David Gair, and I recently wrote a paper regarding the energy-efficient commercial building tax deduction (IRC § 179D).  The upshot is that the Consolidated Appropriations Act of 2021 recently made this deduction permanent.  As discussed in much more detail in the paper, 179D allows for a tax deduction of up to $1.80 per square foot for the design of energy efficient government buildings.

From the paper:

For many years, Congress has held this deduction somewhat hostage by extending it on a year-by-year basis and not permitting construction businesses to properly plan. Now we have some certainty that this deduction will be around for years to come. The potential benefit is very substantial and can allow the economic incentives to work for businesses and governments with very tight budgets. Careful study can yield great results. Beware, however, that the compliance rules are onerous and properly accredited professionals must be employed. Due diligence on the front end will yield great results and avoid IRS entanglements on the back end.