Retro-commissioning is a process to improve the efficiency of an existing building’s equipment and systems. It can often resolve problems that occurred during design or construction, or address problems that have developed throughout the building’s life as equipment has aged, or as building usage has changed. Retro-commissioning involves a systemic evaluation of opportunities to improve energy-using systems.

The kinds of problems that retro-commissioning can typically identify and fix include:

Equipment or lighting that is on when it is not needed
Systems that simultaneously heat and cool
Belts and valves that are not functioning properly
Thermostats and sensors that are out of calibration
Air flow issues (too much or too little)
Dampers that are not working as designed
Controls sequences that are functioning incorrectly

Many of these small operations and control improvements cost little or nothing to implement, yet some can have significant effects.  For example, sensor calibration not only improves current operations, but also increases the effectiveness of diagnostic monitoring and testing.  

The City has retro-commissioned all libraries and major Parks and Water Utility facilities over the past 3 years.  Facilities plans to evaluate Police and Fire Stations in 2020 and 2021.

Retro-commissioning can produce significant cost savings in existing buildings. Savings vary depending on the building size, age and location, and the scope of the retro-commissioning process. The costs of retro-commissioning activities range from $0.13 to $2.00 per square foot, while payback ranges from 0.2 to 2.1 years. Overall energy savings can reach approximately 15%.