Retro-commissioning applies a systematic investigative process for improving and optimizing a building’s operation and maintenance (O&M).  Retro-commissioning occurs after construction, as an independent process and is typically applied to buildings that have not previously been commissioned.

It is a holistic and systematic process intended not only to optimize how equipment and systems operate, but also to optimize how the systems function together.  Typically, the evaluation is consistent with ASHRAE Level 2 energy audit and most often focuses on dynamic energy-consuming systems, with the goal of reducing energy waste, obtaining energy cost savings, and identifying and addressing existing problems.

Benefits of retro-commissioning include identification of system operating, control, and maintenance issues; reduction of maintenance cost and premature equipment failure; reduction of energy cost and waste; documentation of building systems; training of maintenance staff; and collecting data for long-term planning and maintenance budgeting.