Electric power accounts for approximately 40% of the total energy used in the United States, according to the U.S. Energy Information Administration. For most buildings, electricity is the primary energy source and is the means by which interior lighting, HVAC systems, and information technology (IT) networks are able to function. The components and equipment used to distribute, monitor, and control electric power within buildings can be vast and complex, requiring interaction with many other systems. A proper commissioning strategy is essential to help ensure that electrical systems are installed correctly and are set up to operate efficiently and reliably. When performed correctly, electrical system commissioning can be a useful tool for building operators to help control utility costs, evaluate equipment replacements or upgrades, maintain continuous building operations, and ensure the health and safety of the occupants.
As building commissioning has become more prevalent, it is now widely viewed as a critical part of a facility’s overall risk management strategy. The costs and risks associated with commissioning usually are minor as compared with the typical paybacks returned. Direct energy-cost savings perhaps are the most obvious examples of such paybacks. Many studies, including the most recognized report from Lawrence Berkeley National Laboratories (LBNL), show a 16% median whole-building energy savings can be realized from retro-commissioning (retro-Cx) existing buildings—commissioning performed in a building where none was previously performed. At an average cost of 30 cents/sq ft, the LBNL report found the average payback for retro-Cx to be 1.1 years. Naturally, the precise energy savings and paybacks to be expected for a building depend on a number of factors, but generally, the larger, older, or more complex facilities will experience the greatest rewards. Because electricity accounts for more than 70% of a typical building’s energy consumption, commissioning of the electrical systems plays a large part in realizing these savings. To help offset the total costs associated with commissioning, most major utilities offer incentives and rebates for certain commissioning activities.
Benefits of commissioning
Aside from the financial benefits, there are many other reasons for commissioning electrical systems. Facilities seeking U.S. Green Building Council LEED certification must commission lighting and daylighting controls as well as any renewable energy systems as part of the certification process. In addition, the majority of energy codes and standards currently adopted by jurisdictions, such as those based on ASHRAE 90.1-2016: Energy Standard for Buildings Except Low-Rise Residential Buildings or the International Energy Conservation Code (IECC) now include similar commissioning and functional testing requirements.
While occupancy-control systems are becoming smarter—and are being designed for plug-and-play installation and setup—there still are a number of programming and adjustments necessary to fine-tune the system to ensure coordination with other devices. For example, placement of sensors for daylight harvesting and adjustment of the setpoints requires a certain amount of field coordination. Target illumination levels must be understood and the space and light levels must be measured during the initial programming to ensure the proper response. The timing also is important. Commissioning of daylight-harvesting systems should only occur after all the finishes have been installed and the furniture is placed in the room, because these components affect the light levels within the space. For these reasons, there are many well-intended energy-conservation control systems installed that may not be reaching their full potential.
Electrical commissioning offers a means to help alleviate the risks that facility managers and building owners face in dealing with complicated building systems. Commissioning is not solely a means to ensure that building systems are installed correctly and operating efficiently. It also is a systematic process to identify goals, manage testing and verification, maintain proper documentation, and ensure that the operators of the building systems are properly trained. Commissioning often is viewed as an additional set of eyes for building owners and can reduce construction changes and callbacks while providing additional quality control. Even building insurance carriers are starting to realize that buildings that have been subjected to system commissioning are safer to insure.
For best results, the process for commissioning electrical systems should begin even before a project is started. It is important for the facility to identify the goals to be achieved from commissioning. Perhaps there is a targeted risk that the facility would want to mitigate or simply an overall improvement in system efficiency and reliability. These goals must be clearly stated and defined in a document, which is often referred to as the owner’s project requirements (OPR) for new construction projects or sometimes as the current facility requirements (CFR) when commissioning existing facilities. Organizations, such as ASHRAE, the AABC Commissioning Group, and the Building Commissioning Association provide guidelines and best practices outlining the framework for the commissioning process (see Figure 2).
A thorough commissioning plan must be created that includes roles and responsibilities, a description of the commissioning process activities and schedule, a list of the systems to be commissioned. The plan also identifies the necessary documentation including system verification/startup checklists (for new or replaced equipment), functional performance test reports, operation and maintenance (O&M) manuals, training materials, and so on. For larger and more complex facilities, the parties involved in the commissioning process may include more than just the obvious members, from the building owner and contractor to the electrical system designers. Because the electrical system affects nearly all other building systems, representatives from other trades, vendors, and departments may be required in the commissioning effort. Technicians for building automation controls, fire alarms, security, IT systems, elevators, generators, and paralleling gear are just some of the examples of the parties that may play a role in electrical systems commissioning.
When commissioning for certain energy-conservation goals, it is important to obtain current building system benchmarks. The further this data is broken down, the more useful it will be in identifying areas or systems to be targeted and in tracking how effective energy-conservation measures and commissioning activities are performing. Because one of the fundamental goals of commissioning is to help ensure that systems remain optimized after initial implementation, setting up energy alarms through building automation systems or electrical power monitoring systems can help facility managers actively identify problems. An example of such an alarm could be one that is set up to monitor electrical usage by building or by system against a trended maximum value. Alarms also can be established for something more specific, such as an alarm to identify locations where systems controlled by vacancy sensors are operating continuously, indicating a potential problem with an occupancy sensor or control component. Because buildings never remain in status quo, retro-Cx and recommissioning activities offer an opportunity to re-evaluate whether metering and monitoring points should be adjusted or added.