The 179D tax deduction incentivizes energy efficiency in commercial buildings. It offers up to $5.00 per square foot for installing energy-efficient systems like HVAC, lighting, and building envelopes. Building owners and designers of government-owned buildings can claim the deduction. To qualify, the building must achieve a 50% energy savings compared to a reference standard, with certification by a qualified professional. This deduction promotes sustainable building practices and provides tax savings.