Feature Article

The Case For Commissioning

The San Francisco Federal Building’s orientation takes advantage of bay breezes through a massive perforated stainless-steel skin.

Photo: Roland Halbe

As recently as 20 years ago, HVAC, plumbing, and lighting systems were unsophisticated, consisting of moving parts rather than solid-state components, and not networked. Comparatively low energy costs provided little incentive to specify energy-saving HVAC systems that may also be complex and expensive. Cost and ease of maintenance were a higher priority. In warm seasons, cool air was simply forced in as necessary, often continuously. Similarly, tracking building performance was a manual process. “It used to be that facility engineers recorded performance manually in logs, and the information was never completely accurate,” explains Gary Pomerantz, PE, a mechanical engineer with the New York office of Flack + Kurtz, the engineers for the recently completed New York Times headquarters in midtown Manhattan. “Now computers record the data, which, in turn, can be accurately evaluated to determine trending. If the trends suggest the equipment isn’t operating optimally, the data will determine whether there is a problem.”

Then it would seem buildings built in the 21st century are evolving, albeit slowly, from energy-devouring monsters to high-tech, energy-efficient machines. However, with progress comes complexity. In simpler times, contractors were responsible for making sure that the HVAC, plumbing, and electrical systems were properly installed and operational when the occupants moved in. That process is called “testing, adjusting, and balancing” (TAB). Only very complex buildings, such as labs or hospitals, were subjected to more comprehensive performance testing, which is part of the commissioning process.

Now, most commercial buildings are sufficiently complex to benefit from commissioning. In this process, a building undergoes testing of its engineering plant, electronic systems, and all other equipment. It also involves training plant managers, engineers, and maintenance staff in the care and operation of all the systems. Advanced computerized management tools and the growing need for energy-efficient and sustainable buildings demand a comprehensive commissioning process. With all of the technological advancements of the past two decades, one might think buildings could commission and operate themselves in a plug-and-play scenario. On the contrary, it’s the interdependence of these networked systems that complicates a building’s operation and therefore affects its performance. The more complex the relationship between functions, the more coordination is needed.

Today, as more owners are adding value to their projects by seeking LEED certification, commissioning responsibilities are often contracted to an independent third-party provider, a commissioning agent, who ideally sits at the table with the architects, engineers, and client at the start of the process. The relationship between sustainability and commissioning cannot be underestimated. As a result, commissioning has emerged from the purview of specialized structures, such as laboratories and hospitals where bio-safety is critical, to play an important role in new construction. Quality-assurance testing begins in the design phase and continues through construction and after occupancy. The following two case studies show how two clients—one private, one public—have responded to the complexities of building high-performing buildings in the 21st century.

The U.S.’s Largest

The U.S. General Services Administration (GSA) is responsible for meeting the space requirements of federal agencies, making its real estate portfolio the largest in the U.S. Among other duties, GSA sets policy and standards for architecture, engineering, construction services, and project management. Private-sector design teams must follow stringent guidelines, not the least of which is GSA Public Buildings Service’s Total Building Commissioning process for quality assurance in both new construction and facility modernization. The process includes validating and documenting the performance of the total building and its systems to determine if they meet the design requirements of GSA.

GSA’s new San Francisco Federal Building (SFFB) was designed by Thom Mayne, FAIA, principal of Santa Monica, California-based Morphosis, and the Los Angeles office of the international engineering firm Arup, which provided seismic, structural, mechanical, electrical, and plumbing services. GSA intended the 18-story, 605,000-square-foot SFFB to be a model of sustainable design. Many of the building’s features will be precedent-setting for GSA. A narrow footprint ensures employees will have access to daylight. Skip-stop elevators are meant to encourage walking and social interaction. The building features extensive use of natural ventilation for cooling, thermal mass storage, and both passive and active shading strategies.

The building’s exterior skin consists of a glazing system that incorporates computer-controlled operable window walls, which modulate the amount of natural ventilation across the office-tower floors according to space temperature, outside air temperature, wind speed, wind direction, and other environmental factors. The building also incorporates extensive use of daylighting to reduce dependency on electric lighting. For enclosed private offices and on lower floors, under-floor air-supply and overhead VAV air-distribution systems deliver conditioned air. There is a central chilled-water and hot-water plant in the facility.

Because the SFFB represents a milestone for GSA, the agency is conducting extensive post-occupancy evaluation (POE) to determine if the completed building is delivering the comfort, energy-efficiency and operating-cost savings it was designed to deliver. GSA plans to apply the results in a “feed-forward” process for future federal buildings.

GSA hired San Francisco-based Enovity to be the LEED commissioning authority for the HVAC, electrical, and building automation systems. Jonathan Soper, PE, a principal at Enovity, says they are still commissioning the Lutron lighting controls, which is typical for complex systems, but the majority of the firm’s time is spent on the building management system (BMS), a direct digital system that runs HVAC-related equipment. At the SFFB, the BMS is referred to as the energy management and control system (EMCS). It’s programmed with a sequence of operation, somewhat like a narrative, developed by the project’s mechanical engineer to explain how the mechanical system should operate. “We’re trying to refine that sequence so it can function in a way that makes sense for the building’s occupants,” Soper says.

He says for a building this complex, an off-the-shelf, cookie-cutter control sequence wouldn’t work. Thus, Enovity is looking in depth at temperature trends and other details to see how the operable windows should function in order to achieve the temperatures needed for occupant comfort for each tenant on each floor. Soper stresses this sequence could not have been finalized before the building was occupied, as it depends on a number of site-specific criteria like occupant preference, changing weather patterns, and unknowns that computer models cannot analyze. It takes time, too, since the building has nearly 8,000 control points, with at least 2,000 of those points needing careful review by the commissioning agents. Enovity is particularly interested in a well-functioning building, since the firm also has been hired by the client to be its operations and maintenance contractor at the site.

Among other directives, Enovity will monitor energy use for the first 18 months after occupancy to verify the building exceeds California’s stringent energy code—Title 24—by 15 percent. The data will be used to validate (or recalibrate) the models used to predict energy consumption. Arup’s mechanical engineer, Erin McConahey, PE, talks of the engineer’s role as the author of the sequence of operation. A properly working control system reacts to feedback from a device, such as a thermostat, in order to bring the system back into alignment with the desired conditions. It monitors and controls the automated environmental systems to ensure all the equipment performs as designed. In commissioning, the programming and control devices are tested, adjusted, and calibrated by a third party, such as Enovity, against the original intent of the written sequence of operations.

“There are two kinds of testing: pre-functional and functional,” explains McConahey. “The goal of the pre-functional testing is to ensure there are no malfunctioning devices. In functional testing, the engineer may simulate a situation in which the control system must correct a malfunctioning device, such as a valve, sensor, or thermostat.”

Meanwhile, a team from the Lawrence Berkeley National Laboratory (LBNL) will measure temperature and air quality in representative naturally ventilated spaces over an 18-month period. The results will give the client unprecedented information about how well a naturally ventilated space performs over time, under varying weather conditions, and occupancy loads. At the same time, another team from Carnegie Mellon University will measure acoustics, light, air quality, and thermal conditions for comparison to the same measurements taken in the occupants’ former offices.

Media Giant on a Mission

After nearly 100 years at the country’s most famous intersection, The New York Times Company moved to a new headquarters a few blocks west of its eponymous Times Square. Its 52-story, 1.6 million-square-foot building will unite most of the company’s 2,500 employees. The tower will also provide commercial office space, which is being leased by the Times’ development partner, Forest City Ratner Companies. Designed jointly with the Renzo Piano Building Workshop, FXFOWLE, and Gensler, the building represents an unprecedented and ambitious collaboration among the client, developer, government laboratories, university researchers, and AEC team members.

From the beginning, the Times envisioned a headquarters that was literally transparent—with floor-to-ceiling glazing—to symbolize the transparency of a major news organization. The company also wanted a sustainable building, which meant studying a variety of methods for shading an all-glass envelope. Throughout the process, the client took an active and aggressive role in the planning and design. David Thurm, vice president and chief information officer for The New York Times Company, has led the project since it began in 2000. Thurm acknowledges, “This is a once-in-a-lifetime opportunity.” It’s the difference between owning and renting. Since the Times intends to reside in its new home for a hundred years, the priorities are different from those of the short-term-leasing tenant.

The Times was seeking an innovative, high-performance building on a tight budget, so to assist the process Thurm and his team decided to research the design issues themselves. Aware of the facade and lighting research conducted at the Lawrence Berkeley National Laboratory (LBNL), the Times partnered with the labs to find sustainable technologies that could be integrated into the design of its new headquarters. A partnership was eventually established between the client, LBNL, industry, and several public funding agencies, including the New York State Energy Research and Development Authority, to conduct field tests on emerging technologies for facade daylighting systems. For nine months, scientists conducted tests on commercially available automated technologies in order to collect data, including shading devices and daylight harvesting, in a full-scale, 4,500-square-foot mock-up, built near one of the Times’ printing facilities in nearby Queens, New York. Gensler, the interior architects for the project, monitored the human factors at issue by mocking up the interior and having workers perform typical office tasks.

What does budget and design have to do with commissioning? Everything. Commissioning follows the rules set forth in the specifications, which historically have focused on quality assurance and equipment operation. With the Times building, the client and the team completely reinvented the process by switching to a performance-based long view coupled with incentives. Therefore, not only were the contractors and subcontractors invited to pre-bid workshops, but pre-screened manufacturers were also included to learn about the Times’ extensive research into materials and systems. FXFOWLE principal Bruce Fowle, FAIA, calls this effort “eliminating the fear factor.” He acknowledges that when atypical strategies are introduced into the construction documents, contractors will pad their bids as a hedge against uncertainty. The more information they have, the more accurate their bids and the fewer callbacks they will have to endure post-occupancy.

Boldly, the client opted to create an unusual procurement specification. Eligible manufacturers were invited (and given a stipend) to develop, test, and prove that their products would perform as designed. Eventually Lutron and MechoShade won the opportunity to create an integrated, dynamic lighting and shading package which, because of the extensive testing and research prior to design, fell within the typical lighting budget for a Class-A building.

The Times also opted to deliver air on its own floors through a raised-floor system rather than through conventional ceiling diffusers. Because there are few examples of this system in U.S. buildings (Thurm claims this is the first large installation of under-floor air in Manhattan), the client hired Flack + Kurtz, which has done pioneering work in this area, to design this atypical air-distribution system. In a perfect example of commissioning-as-you-go, the client conducted an “under-floor summit” with HVAC professionals to develop a protocol for constructing this type of system. Mock-ups were tested and double-checked by an expert in fluid dynamics. This enabled the engineers to continue to improve the design prior to installation. As the kinks were worked out of the design, the engineers were reasonably certain that once the complex systems were installed in the new building, the need for time-consuming and expensive commissioning would be significantly reduced.

As the federal and the New York Times buildings illustrate, commissioning has evolved from a perfunctory make-sure-everything-works procedure to an integral part of the design process. Performance-based specifications require systems be optimized after they’re verified. To keep up with the new generation of building systems, better controls are constantly being developed to measure and record every parameter to ensure not a Btu is wasted.

Justifying the commissioning process in a construction budget is not difficult, at least in terms of potential savings. One way is to seek LEED certification. For a new construction (NC) certification, the owner must implement a commissioning process that meets LEED-NC’s minimal guidelines and can earn an optional point for exceeding them. For those not seeking certification, an economic case for commissioning can be made using precedents and independent studies. The California Commission- ing Guide cites a study that found “commissioning reduced change orders by 87 percent, contractor callbacks by 90 percent, and reduced the total construction cost by 4 percent to 9 percent.” The Guide suggests estimating the construction-phase cost savings at the beginning of a project and then transfer them to the design and commissioning budgets.

And yet, decision-makers’ uncertainty and skepticism continue to stall widespread implementation. LBNL attempted to give hard numbers to the process of commissioning in a 100-page report published in December 2004, titled “The Cost-Effectiveness of Commercial-Buildings Commissioning: A Meta-Analysis of Energy and Non-Energy Impacts in Existing Buildings and New Construction.” The researchers found that for new construction, median commissioning costs were $1.00 per square foot, representing 0.6 percent of total construction costs. The energy savings alone yielded a median payback time on the commissioning costs of 4.8 years. For existing buildings, the researchers found median commissioning costs of $0.27 per square foot, with whole-building energy savings of 15 percent and a payback time of 0.7 years. The report concluded, “While not a panacea, [commissioning] can play a major and strategically important role in achieving national energy-savings goals—with a cost-effective savings potential of $18 billion per year or more in commercial buildings each year across the United States.”


Published January 1, 2008

Hart, S. (2008, January 1). The Case For Commissioning. Retrieved from https://www.buildinggreen.com/feature/case-commissioning