Commissioning is the process of ensuring that building energy systems are designed, installed, functionally tested, and capable of being operated and maintained according to the owner’s operational needs. By using building inspections and systems testing, commissioning can provide quality assurance and systematically improve energy systems’ efficiency and operation (particularly in HVAC and air distribution). In addition to providing energy savings, commissioning can often increase comfort for building occupants. When the commissioning process is applied to an existing building that hasn’t been commissioned before, it’s called retrocommissioning (RCx).
Monitoring-based commissioning (MBCx), also known as continuous optimization, persistent commissioning, or ongoing commissioning, is similar to RCx in that it’s a process applied to existing buildings to keep them performing at optimal levels. But where RCx requires personnel to periodically tour the facility to identify potential measures, MBCx uses sensors and software in addition to standard RCx practices to provide a real-time account of systems within the building. This method results in more persistent energy savings than conventional commissioning (Figure 1).
What are the options?
To explore the effectiveness of MBCx systems, Lawrence Berkeley National Laboratory (LBNL) studied the implementation of permanent energy information systems for 37 buildings and 9 power plants. As explained in the 2009 LBNL report Monitoring-Based Commissioning: Benchmarking Analysis of 24 UC/CSU/IOU Projects (PDF), the facilities received ongoing commissioning based on the metered data. A total of 1,120 system deficiencies were located (Figure 2).
The LBNL report concluded that MBCx is often extremely cost-effective. The facilities involved in the benchmarking analysis found average energy savings of 10 percent—with some achieving up to 25 percent—and a median simple payback period of 2.5 years. Median commissioning costs were $1.00 per square foot.
What makes MBCx unique is the technology that enables constant monitoring of a facility. Along with a range of other functions, a building automation system (BAS) will perform fault detection and diagnostics (FDD) to highlight systems and equipment that aren’t performing optimally.
These tools allow energy managers to record energy consumption and root causes over time (such as ambient conditions or other common causes in commercial buildings). They also enable users to create a predictive model relating building energy consumption to causes and use the model to:
- Identify periods of best performance
- Quantify savings
- Set targets for reduced consumption
- Compare actual consumption to best practice
- Determine when energy consumption is higher than expected
- Initiate actions to correct variances
Due to the highly involved process of using a BAS, vendors will often offer training on creating facility-based benchmarks and managing the alerts that the system provides.
How to make the best choice
Texas A&M University pioneered the concept of MBCx, trademarking its specific approach as Continuous Commissioning®. MBCx is most commonly performed by a third-party contractor, who installs the energy management system and trains facility staff in the monitoring and upkeep required to use it. While performing the MBCx process and taking a look at the entire building’s energy use, it’s a good time to consider installing additional equipment for increased energy savings. This includes programmable thermostats, occupancy sensors and lighting controls, smart power strips, adjustable-speed drives, and more. When looking at alternate contractors or other forms of energy management software, a good rule of thumb is to compare what they offer to Texas A&M’s comprehensive process.
All energy management systems should diagnose failed or nonoptimized equipment, and over time they should prompt repair or proper calibration that leads to further long-term savings. Texas A&M’s process involves several steps that are facilitated by individual modules within a software package and provides an excellent example of what to look for when choosing energy management software.
Step 1: Assess opportunities A module asks for input data such as energy consumption from utility bills, then it calculates savings potential and provides an early estimate of savings.
Step 2: Build a software model After a site assessment gathers diagnostics on the facility, the resulting data is entered into the second module to provide the basis for a model of the facility’s energy use. The model is then calibrated to match the measured energy consumption.
Step 3: Implement This module sets up trend logs associated with specific systems and equipment in the facility; trained engineering staff can monitor those logs.
The module continuously identifies problems, highlighting systems that can be tweaked and optimized. Opportunities for improvement include, for example, old equipment that needs replacing, mechanical fixes and retrofits, temperature setpoint adjustments in a manufacturing process, heat-transfer maintenance, design changes, and modified employee behavior.
Step 4: Rebuild and recalibrate model Once measures have been implemented and the facility is running optimally, the model-building module should be used once more to provide an updated, stricter standard for keeping the facility at its best.
Step 5: Validate This module will calculate savings from measured data by comparing each improved model to its baseline while also providing a graphical output.
Step 6: Sustain To make savings stick, this module monitors performance and provides whole-building FDD. The module determines savings degradation over time and reports where savings are being lost.
Step 7: Dashboard This module summarizes data and provides different snapshots on issues such as energy consumption, energy load, or air quality; it’s useful for facility managers or CEOs who are keeping an eye on building performance.
Even the best monitoring systems won’t be effective unless a highly trained team of building engineers, control contractors, mechanical contractors, and other professionals is assembled. These experts are needed to interpret and analyze the recorded building data. The strength of MBCx lies in the proactive nature of the approach, instead of merely fixing systems once they break. This proactive monitoring of systems may require building owners to develop new business procedures to best support new technology and personnel. Once MBCx is initiated, it’s important to start slow, with a manageable workload, to avoid overwhelming engineering staff. An ongoing operational budget should be allocated to address faults and support facility improvement because MBCx is not worth implementing without extended commitment.
To help implement MBCx, utilities may offer incentives that help reinforce the long-term management of equipment. By combining software analysis of building data, and combining it with an engineering team’s expertise, MBCx is the next step in facility engineering operation and maintenance.
What’s on the horizon?
Since 2004, California investor-owned utilities have partnered with the University of California and California State University systems to support constant development of MBCx. MBCx has continued to mature in California and across the nation, increasingly taking its place as an aspect of mainstream commissioning. MBCx has proven to offer permanent energy savings with the help of trained staff. However, many utility incentive payment structures still rely on savings snapshots as opposed to long-term assessment. As savings accounting increases in adoption by commissioning providers, the longer-term persistent savings will likely begin to support long-term incentive payments. As energy information technology continues to develop, MBCx will continue to evolve and improve in effectiveness.
Who are the manufacturers?
Results from undergoing MBCx vary highly based upon the level of expertise and commitment of engineering staff. Below is a list of firms that are experts in MBCx and have been legally licensed to perform the specific rigorous ongoing commissioning process. If your facility is interested in purchasing a building automation system, see our BAS page for in-depth coverage.
- HHS Associates
- Texas Energy Engineering Services, Inc. (TEESI)
- Command Commissioning LLC
- Smith Seckman Reid, Inc (SSR)
- Sain Engineering Associates, Inc (SEA)
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