Retro-commissioning (RCx) is a systematic, documented process that identifies low-cost operational and maintenance improvements in existing buildings and brings the buildings up to the design intent of its current usage. In the retro-commissioning process, we focus on energy-using equipment, such as mechanical equipment, lighting and related controls, and optimizing their performance rather than relying on major equipment replacement. Typically, a retro-commissioning project will result in any, or all of the following: