Accounting for about 40 percent of energy consumption in the United States and contributing more carbon dioxide to the atmosphere than entire nations, existing buildings are becoming the proverbial elephant in the room of energy security. Few had the benefit of commissioning when built and even fewer have undergone existing-building commissioning (EBCx), or, as it was more commonly (and less accurately) known, retrocommissioning.

Although it has been around since the early 1990s, EBCx is little understood. It combines elements of new-building commissioning, the energy audit, and the building “tune-up” (Table 1).

EBCx differs from new-building commissioning considerably in that there is no design phase. And it differs from the energy audit in that it includes more tasks and lasts for a longer period of time. In definition and practice, EBCx is similar to Continuous Commissioning, an “ongoing process to resolve operating problems, improve comfort, and optimize energy use.”¹

“While most commissioning processes focus on bringing building operation to the original design intent, Continuous Commissioning focuses on optimizing heating-, ventilation-, and air-conditioning-system operation and control for the existing building conditions,” Energy Systems Laboratory, a division of the Texas Engineering Experiment Station, which trademarked the term “Continuous Commissioning,” and a member of the Texas A&M University System, explains.²

In short, EBCx is “a systematic process for investigating, analyzing, and optimizing the performance of building systems through the identification and implementation of low/no-cost and capital-intensive facility-improvement measures and ensuring their continued performance,” the Building Commissioning Association says. “The goal of EBCx is to make building systems perform interactively to meet the current facility requirements and provide the tools to support the continuous improvement of system performance over time.”³

What's more, according to Portland Energy Conservation Inc. and Oak Ridge National Laboratory, “Not only does retrocommissioning identify problems that occurred at construction, just as traditional commissioning does, but it also identifies and solves problems that have developed during the building's life.”⁴

MORE THAN AN ENERGY AUDIT

Many clients are asking for EBCx, but describing it as a list of services amounting to an energy audit.

The primary purpose of an energy audit is to identify energy-saving opportunities to reduce yearly operating costs. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) defines three levels of energy audits:

• Level I, which involve a visual inspection of a building's mechanical and electrical systems and interviews with building operating personnel.

• Level II, which include a more detailed building survey and in-field measurements.

• Level III, which provide dynamic energy models of existing systems and proposed capital improvements.

Building owners and operators have become so used to the idea of the energy audit over the last 30 years that EBCx is being forced into a similar mold to get contracts signed. This is unfortunate for clients because the EBCx process goes beyond the traditional energy audit.

With EBCx, additional information is gathered up front, before the audit portion of a job begins. This comes through the process of developing a current-facilities-requirements (CFR) document. These requirements usually are neither the original design intent of the building nor the original design intent of the various building systems. The development of the CFR leads to the “investigation” portion of the EBCx process, which is similar to an energy audit, but develops into a long-term strategic plan for a facility. This plan anticipates planned equipment obsolescence, as well as shifting corporate goals.

The first sign that a client is requesting an energy audit in EBCx clothing is that the deliverables do not include the CFR. This indicates the client is seeking short-term cost savings, rather than long-term strategic operational improvements. The EBCx process not only identifies ways to spend less; it provides a foundation for ensuring a building's goals are met in the future.

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