What is Re-Commissioning?
Re-commissioning or Retro-Commissioning refers to a quality assurance process for existing buildings to optimize performance and improve building operation that includes verifying and documenting that the building and its systems and assemblies are operating efficiently and meet the current requirements of the building. Many existing buildings never went through an initial commissioning process after construction. Changes in design or improper installation can lead to systems working inefficiently. Additionally, building systems degrade and lose efficiency over time make re-commissioning and ongoing commissioning essential steps in the overall quality assurance process (see Figure 1).
How to Implement Re-Commissioning
The first step in the re-commissioning process is to designate the re-commissioning team, which often includes the Commissioning Agent (CxA), Building Owner, Construction Manager/General Contractor, Contractors, maintenance and operations personnel, and occupants. The Building Commissioning Association (BCxA) recommends hiring a third-party independent CxA with excellent written and verbal communication skills, current engineering knowledge and extensive hands-on field experience regarding building systems, including principles of building system performance and system start-up, balancing, testing and troubleshooting, as well as knowledge and experience with building operation and maintenance procedures and the building and design process.
The re-commissioning team assures the completion on all of the steps in the re-commissioning process and the realization of building objectives and develops the building re-commissioning plan, which outlines and organizes the commissioning process schedule and allocation of resources and includes details of systems tests and procedures (i.e., energy audit), system and equipment checklists, and testing and documentation responsibilities. The re-commissioning process should include an energy audit, which provides an analysis of the building’s energy use and potential for savings. LEED requires energy audits to meet both the requirements of the ASHRAE preliminary energy use analysis and an ASHRAE Level 1 walk-through assessment identified in the ASHRAE Procedures for Commercial Building Energy Audits or equivalent.
Building re-commissioning plans may include some or all of the following building systems and green building elements (as applicable):
- HVAC systems (control settings and sequencing)
- Building assembly (envelope, interior, paths of egress)
- Conveying systems (elevators and escalators)
- Protective systems (fire suppression, lightning protection)
- Plumbing (water distribution, sanitary or stormwater)
- Electrical (power distribution, lighting)
- Communication systems (telecom, wireless networks, sound, video)
- Alarm Systems (fault detection, security, leak detection)
- Indoor air quality (moisture, airborne particles)
- Indoor environmental quality (acoustics, thermal comfort)
- Renewable energy (photovoltaics, wind energy)
- Smart building technology (advanced metering, building automation systems)
- Energy storage and back-up power generation systems (ice storage, batteries)
- Alternative water reuse systems (greywater recycling, composting toilets)
The re-commissioning process provides testing and documentation that establishes valuable performance benchmarks, and a baseline for the future operation and the ongoing commissioning of the building. Re-commissioning teams may consider issuing an occupant survey before re-commissioning to identify areas of concern and focus. The final re-commissioning report provides building upgrade recommendations and operations and maintenance improvement opportunities and describes the potential improvement, estimated implementation costs, and savings for each opportunity.
For a more detailed overview of the re-commissioning process, including retro-commissioning and ongoing commissioning see the Building Commissioning Association’s Existing Building Commissioning Best Practices and Tools Handbook.
- Optimized building systems and quality assurance.
- Lower utility bills through reduced energy savings of 14-16%.
- Improved indoor environmental quality and occupant comfort.
- Fewer building system issues at building turnover.
- Enhanced operation and maintenance.
The cost of not re-commissioning equals the costs of correcting mistakes plus the costs of inefficient operations. Re-commissioning for existing buildings costs on average $.30 per square foot for commissioning agent services., Reduce the costs of on-going re-commissioning by installing systems that make that process more manageable such as smart metering (see Smart Metering). The payback period for costs in extra time and labor and parts are around one to four years. Other estimates find that payback can be less than two years and often less than six months.
See the New Jersey Office of Clean Energy for available programs and incentives related to commissioning.
Re-commissioning contributes to a building’s resiliency by providing feedback on the status of critical building systems and notifying building operators when and where a problem exists, ensuring that a building performs optimally during both normal operations and emergencies. Re-commissioning identifies opportunities for energy savings and if implemented, help to reduce stress on the grid and the likelihood of grid failures.
 Building Commissioning Association (BCxA). 2018. Existing Building Commissioning Best Practices including BCxA Essential Attributes. Updated May 2018. https://www.bcxa.org/wp-content/pdf/BCA-Best-Practices-Commissioning-Existing-Construction.pdf (accessed January 15, 2019).
 Building Commissioning Association (BCxA). 2018. New Construction Building Commissioning Best Practices including BCxA Essential Attributes Updated May 2018. https://www.bcxa.org/wp-content/uploads/2018/11/BCA-New-Const-Best-Practices-2018-05-14-V2.0.pdf (accessed January 15, 2019).
 USGBC. 2019. LEED v4.10 O+M Beta Guide https://www.usgbc.org/resources/leed-v41-om-beta-guide (accessed January 23, 2019).
 Building Commissioning Association. 2016. Existing Construction Building Commissioning Best Practices and Tools https://www.bcxa.org/wp-content/pdf/BCA-Best-Practices-Commissioning-Existing-Construction.pdf (accessed Jan 11, 2019).
 GSA Sustainable Facilities Toolkit. 2018. Building Commissioning. https://sftool.gov/search?query=Building+Commissioning (accessed Jan 14, 2019).