Building commissioning is often viewed as a one-time procedure performed during a building’s initial construction, among hundreds of other tasks. (That is, if commissioning was even performed at all… which is another topic in itself!) An investment was made into ensuring that the newly constructed systems were indeed installed correctly and operating properly. So then, if a building was already commissioned, why would you want to recommission it?
Before answering that, we should first define what recommissioning is. Simply put, recommissioning is a process that helps get a building back to the operational performance that was intended from the initial design and construction. It’s much like a tune-up for your car. Commissioning occurs during the design and construction of a building. Add the “re” to commissioning, and it implies that you are “commissioning again” an existing building that was previously commissioned. In a similar way, when you add “retro” to commissioning, it implies that you are “going back and commissioning” an existing building that was never commissioned before. According to the Building Efficiency Initiative, “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.”
The process to recommission is often and best done on a planned, recurring basis. This is because buildings change over time. Just because a building’s systems were optimized when it was first commissioned, doesn’t mean they will stay that way forever. As with most things, building systems wear and their performance degrades over time. For example, a building may undergo a remodel or the way its space is used may change, pieces of equipment fail and are replaced, control setpoints are tampered with, and sensors fall out of calibration. Recommissioning can help to diagnose the source of issues and identify building systems that have drifted, leading to higher energy costs and other negative side-effects. Such issues include duct air leakage, HVAC and lighting left on while a space is unoccupied, airflow not balanced, dampers and economizers not working properly, improper setup or failure of controls, and much more.
Identifying and correcting these issues through a recommissioning process will lead to significant energy savings. It is important to recommission your building every 3-4 years. According to a report by Lawrence Berkeley National Laboratory, commissioning produced 16% median energy savings in existing buildings with a payback time of 1.1 years. Furthermore, recommissioning results in a healthier and more comfortable environment for the building occupants, which is not as easy to quantify as energy savings but is even more impactful to an organization’s success.