Commissiong, Recommissioning, Retrocommissioning, and Continuous Commissioning
The article discussed what they called a well-known secret among energy consultants regarding EMS and the fact that “Most new or upgraded EMS are not fully checked after installation, leaving significant savings untapped,” “To ensure the EMS will deliver promised savings, it needs to be commissioned upon installation or retro-commissioned thereafter,” and “Independent studies show cuts in energy cost ranging from 2.5 to 49.4%, average 20%, with paybacks three months to 4.6 years.”
The goal of commissioning is to ensure systems are meeting their design performance requirements and/or finding and correcting a variety of original installation mistakes. There is a seemingly endless variety of these mistakes, such as EMS programming errors, erroneous sequences of operation, simultaneous heating and cooling, VFDs running needlessly at full speed, humidity limits set wrong, failed or faulty components that need to be repaired, correcting original wiring problems, inadvertent tampering by staff and even sabotage, or simply not staying on top of the EMS maintenance.
In my experience, this is an understatement. EMS today are, for the most part, dramatically unorganized, therefore underutilized by staff, misapplied by the controls contractor (CC) and mechanical engineers, and misunderstood by all, including administration personnel.
Whether the systems are new or not, a comprehensive continuous commissioning program will ensure they provide optimal performance at all times, and produce expected comfort, reliability, and savings.
One Size Doesn't Fit AllThe commissioning process often breaks down when mechanical design engineers specify basic, or frequently “canned,” sequences of operation, and they under- or over-engineer systems. The onus is then on the controls contractor - not only to apply it correctly, but to find equipment performance anomalies that exist in virtually all instances and correct for them. Generally speaking, mechanical equipment and systems are basically alike in nature; however, each take on a unique performance profile and often operate dramatically differently from one another, facility to facility, and from season to season.
Success then hinges on the competency of the CC and specifically, the particular CC technician on the job site. Although project specs routinely call for seasonal performance commissioning adjustments, often there is little or no accountability. Therefore, it rarely ever happens, and as a result, the CC performs tests relative only to operating conditions at that particular point in time.
Even when extra money is spent to commission the EMS and associated HVAC equipment, good intentions are less than effective for the customer and energy savings. For the customer’s sake, one way to achieve savings is for the mechanical design engineer to hold the CC accountable for providing specific feedback on equipment performance profiles at specific points of equipment operating conditions. For example, a 60°F daylight load cooling day, or a 35° day to ensure heating cycle and damper positions are correct.
In my opinion, it’s not a matter of spending extra dollars on commissioning systems; the key is specific critical information at the right time in the equipment performance cycle, and this work is easily included in the standard project commissioning cost.
Oddly enough, the federal government is on the right track. The DOE’s Federal Energy Management Program (FEMP) pursues “an ongoing commissioning process to maintain systems at optimal performance at all times.” The FEMP is pushing this method through its continuous commissioning process and claims this process “has produced typical savings of 20% with paybacks under three years, (often one to two years) in more than 130 large buildings.”
The FEMP’s Continuous Commissioning Guidebook, Maximizing Building Energy Efficiency and Comfort was developed for federal energy managers. It presents a comprehensive ongoing process to resolve operating problems, improve comfort, optimize energy use, and identify retrofits for existing commercial and institutional buildings and central plant facilities.
While the Continuous Commissioning Guidebook is a great start, it is not as comprehensive as it could be. For example, very little reference is made to EMS/BAS management and utilization, given the critical role it plays in this process.
Getting Your Money's WorthIn today’s world, with natural gas costs tripling and electric projected to increase shortly in Ohio by 25%, energy costs can represent one of the most significant expenditures faced by a company. The EMS is an essential tool to ensure comfort and reliability while driving down cost per square foot and BTU consumption.
There are large facilities and organizations with huge financial investments, millions of square feet of EMS, enormous databases, and underutilized networks, with no solid management standards to make best use of these extremely sophisticated, powerful, and complex systems. A properly administered EMS is by far the most powerful and useful tool that facility managers generally don’t take advantage of.
EMS can provide instant access to an all-inclusive storehouse of documents and information, such as balance reports, equipment and design specifications, and construction standards.
From the novice and general maintenance staff to the energy manager, and from the CC and mechanical engineers to the administration, EMS management, diagnostic, and navigation tools are designed for all levels of users and benefit from the continuous commissioning process. Just reacting to hot/cold calls and alarms simply isn’t enough. Managing a building requires daily monitoring of EMS data, quickly and accurately measuring against optimal performance levels of control, to instantly tell if systems performance is staying on target or not, proactively identifying equipment and system malfunctions, and manual energy override issues.
A comprehensive continuous commissioning process is particularly important in large health care facilities where renovation, remodeling, building additions, and new building construction projects are a way of life.
In stark contrast, some studies actually recommend a four- to five-year interval between re-commissioning or retrocommissioning efforts as a matter of routine operations. By virtue of this recommendation to address equipment energy performance every four to five years, continuous commissioning is obviously a very cost-effective tool for facility managers.
ConclusionApparently, the continuous commissioning process is still a secret and elusive to most. Unlike commissioning new equipment or systems upon project installation, the energy savings generated by recommissioning and retrocommissioning are easy to benchmark, measure, correct, verify, and guarantee.
Energy performance contracts are a quick way to jump start an energy management program for an organization, by being self-funded through guaranteed energy and operational savings. However, realized efficiencies will slip backward and revert to previous levels if they are not maintained with a comprehensive continuous commissioning program.
Any full-time facility energy manager in a large organization who can’t save 10 times his salary each year as a matter of energy/utility cost avoidance isn’t realizing his full potential, either.
Finally, whether commissioning a new project or recommissioning existing systems, engineers may encounter a common but false assumption that equipment or systems which waste enormous amounts of energy will produce customer and occupant comfort complaints. This is, of course, patently false. ES
Sidebar:Going Retro For Future SavingsBy Mike Farshchi, P.E.
Retrocommissioning is the process of applying building commissioning procedures to an existing building in operation. This is separate from any equipment start-up or any maintenance procedures done during remodeling or building upgrades. The USGBC has recognized the importance of retrocommissioning by awarding it an innovation point in its LEED® for existing buildings (LEED-EB) ratings system.
Retrocommissioning can reduce building energy use and at the same time, it can improve building comfort and health. This process ensures that the previously commissioned systems are still maintained and operated at the correct settings. It is also a chance to optimize operations even beyond the intent of the original designers using the experience of operating the building as a guide. This article will provide some of the factual justification as to how cost effective retrocommissioning really is.
Retrocommissioning takes a broad look at the major pieces of mechanical and electrical equipment and their optimum operation. Perhaps the most key component of this effort is the BAS. We have all seen that existing buildings are being forced to upgrade in response to more demands in data transmission, comfort, sustainability, safety, and security. BAS are playing an increasing role in achieving these objectives and they can be the information pathways underlying the retrocommisioning process.
Improvements to building control systems through renovations and upgrades are common. What is uncommon is to keep current with the overall building commissioning as these changes are made. For example, past efforts to integrate lighting and HVAC controls faced technological barriers in the field. Lack of time and funding at the end of the projects eliminated all or part of the commissioning needed. This usually resulted in the lighting and HVAC controls having only part of the functionality that they could have provided. When building operators are faced with systems that do not operate or communicate effectively, they may bypass some of the installed controls systems.
The focus of retrocommissioning is not on performing expensive capital improvement projects. Instead, building performance is fine-tuned periodically through implementing relatively low-cost energy efficiency measures and maintenance improvements. Optimally, capital improvement projects, equipment repairs, and testing and balancing must be completed prior to retrocommissioning.
The scope of retrocommissioning includes providing system interactions, incorporating changes due to renovations, implementing PM measures, and correcting improper sequences of operation and controls.
The cost and energy savings of retrocommissioning depends on building complexity. Studies indicate that the process is a cost effective one. In 2004, Lawrence Berkeley National Laboratory (LBNL) studied the retrocommissioning of 150 existing buildings. These buildings had a median size of 151,000 sq ft and were located in 15 different states. The average cost of retrocommissioning was $0.27/sq ft. The process yielded an average of 15% building energy savings and paid for itself in less than nine months. The study showed that the longer the operating hours and the higher the energy intensity, the quicker the payback.
Other benefits of the process included improved IAQ, greater asset values, higher worker productivity, improved PM, and increased equipment life. Since paybacks from energy were already so quick, these added benefits were not quantified or added into the payback calculations. The results reinforce the fact that most existing buildings do not function the way they were intended. The original commissioning, however well it was done initially, no longer met the current operating conditions of these 150 buildings.
This is a process that can help to eliminate wasteful operational procedures. The inventory of existing buildings is growing along with the search to reduce building energy consumption. Building owners and operators are paying more attention to this now than in the past. A 2003 Energy Information Administration (EIA) survey report indicated that there are 64,783 million sq ft of non-mall buildings in the U.S. This group of buildings accounted for $92,577 million dollars in annual energy costs. The report also indicated that A/C BAS are not widely installed and even fewer buildings are equipped with lighting BAS. The use of daylighing sensors is even less common. Also, about half the buildings remain partially lit when closed.
Implementation of retrocommissioning requires putting together a comprehensive team with a clear objective and plans to meet the expectations. Participants in the retrocommissiong team can be from several disciplines with appropriate skills. To assist the owners and building operators with commissioning team selection, a few construction trade and design professional organizations have training and certification programs. Some organizations offering certification programs are: AABC Commissioning Group, Association of Energy Engineers, Building Energy Commissioning Association, Building Operator Certification, National Environmental Balancing Bureau, and USGBC. Ideally, this takes place with a combination of in-house and outside experts including:
- Building operators and maintenance personnel
- Contractors and engineers
- TAB and commissioning agents
Farshchi is a project engineer with Chevron Energy Solutions, San Francisco.
E-mail him at email@example.com