There are arguably few buildings that have been correctly commissioned. Commissioning is the last task when building works are nearing completion meaning that there can be more time pressure from builders or owners to achieve practical completion of a project, that can mean that commissioning of the systems may not necessarily be comprehensive as it need to be if time allocation is cut. This can lead to inconsistent temperatures, cause issues for tenants with tenant complains, higher energy use and reduced plant life.
Equally, digital equipment settings can drift over time, even if they have been commissioned well. Checking of individual sensors may not pick up the full extent of any issues. Total re-commissioning of a property is required from time to time to ensure that a property runs to optimum efficiency.
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.
The kind of problems that retro commissioning will identify and fix include:
Chiller co-efficient performance ("COP") with a view to maximising on replacement.
Fans and pumps not running speed drives, which improve both efficient and energy consumption.
Fan sizing to ensure optimum performance of operation.
Systems and controls that simultaneously heat and cool meaning that they are not functioning to design.
Belts and valves that are not functioning properly.
Thermostats and sensors that are out of calibration.
Economy controls that are not working as designed.
Controls sequences that are functioning incorrectly.
Flow on to other essential services such as stair pressurisation systems, fire compartment and a building's fire matrix variable-frequency drives that operate at unnecessarily high speeds or that operate at a constant speed even though the load being serviced is variable.
When equipment is installed, repaired or retrofitted, the benefits of these physical upgrades tend to persist. In contrast, improvements in operations and controls strategies can be easily overridden, reprogrammed, or bypassed so that the resulting comfort and energy savings benefits are less likely to persist over time. Items that may affect persistence include changes in occupancy levels or schedules, changes in space layouts, overriding of control logic or set points by staff or occupants to quickly fix problems, or replacement of systems or controls.