Special report: Test and balance in buildings
After navigating rough times for new construction with more work on existing buildings, test and balance firms are cautiously optimistic about the future—and have some ideas to share with engineers.
The discipline of testing, adjusting, and balancing (TAB) can be traced back as far as the construction of the Pentagon near the end of World War II, and evolved into an essential part of the modern building construction and renovation process. When done properly, TAB—also called test and balance—has tremendous benefits for building owners, both in direct savings and in proper system performance.
Challenges persist, however. TAB is often incorrectly treated as a strictly end-of-the-project task that can be rushed through, and TAB firms must also navigate providing a professional service that is frequently procured via a low-bid process.
To answer a number of questions about challenges currently faced by TAB firms, and where most of their work is coming from, the Associated Air Balance Council (AABC) conducted a survey of 168 TAB agencies in August 2012; 69 companies responded.
All of the companies surveyed are independent testing agencies with no affiliations with contractors, manufacturers, or design engineers.
Building types and sectors
While new construction accounts for the majority of TAB projects among the companies surveyed, a substantial 39% of their work occurs in existing buildings. This suggests that building owners recognize the ability of an independent TAB agency to verify and improve system performance.
The bulk of TAB work is currently in the private sector (46%), with most of the remainder of work fairly evenly divided between state governments (15%), military projects (13%), nonmilitary federal projects (11%), and municipal projects (11%).
Figure 1 shows the distribution of work according to facility type. Leading the way are commercial office buildings (23%), followed closely by health care facilities (21%).
Despite general recognition that this setup is far from ideal, TAB agencies are frequently (56% of the time) subcontracted to the project’s mechanical contractor (see Figure 2). An additional 18% of the time, the TAB agency is hired by the general contractor. Only 19% of the time is the agency hired by the building owner, though this situation is considered ideal by many in the industry because TAB is meant to provide a third-party verification of system performance on behalf of the building owner.
Independence and TAB scope
Survey respondents were asked to share the approximate percentage of jobs specified to be balanced by an independent TAB agency, and the overall average of responses put this number at around 83%. While it would be better if this number were even higher, it does suggest that most specifying engineers recognize that the TAB agency should not be affiliated with other entities that could present a conflict of interest.
Survey respondents were also asked how often over the past 12 months they were asked to perform a number of specific services related to TAB (see Figure 3). Controls verification was reported as the most frequent specific service (34%), followed by site inspection (31%) and kitchen hood testing (27%). Among the other responses, it is notable that at a time when so much attention is devoted to energy savings, duct leakage testing is specified and performed only 13% of the time.
Project timing for TAB services
When TAB agencies are contracted prior to construction, it allows the opportunity to perform a review of systems for balanceability, correcting any issues that would be more costly and time consuming to fix after construction has begun. About 58% of survey respondents said their agency is brought in before construction for at least one-third of their projects, and about 21% of respondents said early contracting occurs as often as half of the time.
Significant issues are often uncovered when TAB agencies are brought in early for assessment, according to responses. The frequency with which these findings are acted upon varies, in part because some agencies perform their review with little time remaining before balancing is to begin. The most commonly reported findings include improperly located or missing dampers and valves, variable air volume (VAV) box sizing, piping issues, and issues with building pressures.
Engineers and the TAB process
Although TAB professionals rarely work for the project engineer, there is no question that the engineer—who controls the content of the TAB specifications, may need to respond to issues discovered during TAB, and is responsible for reviewing the final report—can have a significant impact on TAB procedures.
While engineers have the technical “chops” to understand TAB issues, the fact is that some may not have had the time or the inclination—especially early in their careers—to learn about the specifics and the subtleties of TAB. With this in mind, survey respondents were asked what they wish more engineers understood about the TAB process. A number of common themes emerged, some of them technical in nature but many of them more process-oriented.
- TAB specifications should be developed with the individual project in mind. Detailed specifications that are project-specific avoid confusion and misunderstandings that can lead to delays or unanticipated costs.
- How to read, understand, and effectively use TAB reports. A thorough review of the TAB report can tell engineers a lot about the quality and completeness of the TAB work. An accurate report also provides important information about system performance, any deficiencies, and how to correct them.
- The importance of insisting on an independent agency. If the engineer does not specify otherwise—either by requiring that the TAB agency be certified by AABC or by explicitly requiring that it be independent—the TAB process could be performed by people with direct ties to the installing contractor. An independent TAB agency has no such conflicts of interest that could prevent it from rendering an objective report about system performance.
- The benefits of involving the TAB agency early in the process. “Balanceability” reviews done before installation frequently catch a variety of small problems before they become bigger, time-consuming, and expensive to correct.
- TAB procedures, and what it takes to do the job right. TAB agencies and project engineers should be allies in achieving optimum system performance. Understanding the basics of proper procedures and the time involved makes this alliance stronger.
- The system’s design and functionality has a direct impact on the TAB agency’s measurements. From proper placement of valves and dampers to how the system was designed, or with regard to outright installation errors, the TAB agency’s ability to achieve system balance can depend on factors that are beyond its control.
Challenges and outlook on the future
Survey respondents were asked to identify their agency’s current main challenges in the business, technical, or project administration areas of their operations.
Technical: Many survey responses expressed challenges related to sorting out new technologies and reporting software. Another common issue, a longtime one for TAB agencies, is keeping up to date on rapidly changing controls equipment and software.
Project administration: Overwhelmingly, unrealistic timeframes to complete TAB work and related scheduling issues were the most frequent challenges reported in this category. System readiness for TAB and unclear specifications also received repeated mentions.
Business: Many of these challenges relate directly to the slow economy. Most frequently cited were cash flow issues resulting from slow payment (often by similarly cash-strapped mechanical contractors) for work completed. Others noted that workloads are uneven, not yet rebounding to pre-recession levels—which, in turn, has resulted in intensified competition on pricing for the available work.
Despite recent times being difficult, there is a fair share of optimism for 2013, with 48% of respondents saying they expected their firm’s overall TAB work to increase. Nearly as many (45%) anticipate 2013 to look much like 2012, and only 7% anticipate a decrease. Overall, the vast majority seem to agree that things are at or near the bottom—the only question remaining is when the upturn will arrive.
Ray Bert is deputy executive director and Lexi Gray is director of communications for the Associated Air Balance Council, the only association of independent TAB agencies.
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