Commissioning is a technical process to make sure new buildings perform as designed or restores existing ones (“retrocommissioning”) to proper performance. Commissioning is best done by an expert independent of the original installer.
A 643-building study found commissioning saved 13% of energy with a 4-year payback in new buildings—but saved 16% with a 1-year payback in existing buildings.
Mills, Evan. 2009. Building Commissioning: A Golden Opportunity for Reducing Energy Costs and Greenhouse-Gas Emissions. Lawrence Berkeley National Laboratory. link