Requiring Design Phase Commissioning
The goal of these innovative systems is to save energy and to provide equal or better indoor environmental quality. Too often, however, theoretical gains are not realized in the final product. The reasons span from design and specification through manufacturing, installation, operation, and maintenance. The practice of commissioning is poised to address all of these aspects, however, it needs to be focused more intently when innovative systems are involved.
Market forces with a relatively minor regulatory element largely drive the evolution of standard building equipment and systems. In order to compete, manufacturers and engineers have had to provide reliable products with the lowest possible first cost and low operating cost.
In the current market environment, an innovation must surpass a high barrier to displace a time-tested approach and become incorporated as a standard procedure. Before this happens, the equipment or systems in question must go through a transformation period where those who adopt the innovation incur the associated heightened costs and risks.
When a force that is essentially non-market, such as LEED, drives or accelerates the application of innovations, the barrier is lowered and there is a tendency for those innovations to pervade the market at an earlier stage of development. This is likely to extend the transformation period where adopters incur some of the burdens associated with un-tried or less-tried approaches.
Some examples of equipment and systems considered to be innovative to varying degrees include: heat recovery systems; evaporative cooling; stack-effect cooling; ground-source heat pumps; thermal energy storage; under floor air distribution; low temperature air distribution; and local renewable energy e.g., photovoltaic, solar thermal, and wind energy.
COMMISSIONING DEFINEDThe LEED rating system and similar standards generally call for development and execution of a commissioning plan covering commissioning of energy using building systems and equipment. While various guidelines are referenced, the intensity, or level of detail of the effort remains open ended and is largely left up to the commissioning provider to determine, given the owner's budget allotment.
It is important that the intensity of the commissioning effort be closely tailored to the nature of the systems and equipment being commissioned. Innovative equipment and systems require an intense level of commissioning because they are relatively unfamiliar due to the fact that they are not produced or used in the quantity that standard systems are, and usually evolve faster.
Commissioning of buildings as a specialty, distinct from the designer's role, is relatively new. There is a growing consensus that the industry needs it - but many who believe also find it hard to define exactly what it is.
DRIVING FACTORSOne factor that has been driving the need and growing practice of commissioning over the last decade is the microchip revolution. This has provided the industry with direct digital controls (DDC) systems that are now used in virtually all buildings of substantial size.
Coupled with the proprietary nature of the control marketplace and the rapidly evolving nature of computers, it is almost impossible for an HVAC design engineer to maintain a detailed understanding of the different manufacturers' DDC offerings.
This makes specifying controls for competitive bidding much more difficult than it was when control systems were built of standard off-the-shelf pneumatic components. The solution many designers have arrived at is to specify the control system in terms of written descriptions of performance, and leave the actual application engineering of the system to the vendors, resulting in a design-build scenario for the control system.
Compounding the challenge of assuring the quality level of complex building systems, the current culture seems to drive professionals to become more and more specialized. Hence, the mechanical engineer who in the past might see his design through as it is implemented now finds that productivity demands he stay at his desk and produce more designs instead. The result is that nobody with detailed design understanding is in a position to verify the proper implementation of the design. Both of these trends mean more potential problems for building owners. Commissioning providers are working to identify and correct any such problems as early as possible and boost the quality level of the completed building project.
DESIGN PHASE PERILSIncorporating innovative systems and equipment adds a substantial new level of challenge to this process. One of the basic design phase perils is to overestimate the savings. Most want to save energy and improve performance, but the reality is that easy gains in these areas are rare.
The excitement generated by an innovative approach can also lead to losing track of the building's operational requirements or design intent. What sounds like a good idea at first may not stand up to careful analysis. The anticipated savings may never materialize, and the risk of increasing operating cost due to malfunction or operator error is introduced.
APPLICATION PERILSWhile most buildings are unique, design standards are general by nature, and at best may be tailored slightly for a particular application. When a rating system such as LEED calls for exceeding a standard, the intent is clear. However, care must be taken that the standard is in fact applicable. If the savings stem from the operating criteria rather than the system design and would be present in the absence of the standard anyway, no addition of value through design has occurred.
When an innovative system or piece of equipment is specified, it will clearly not be the same one that worked well on the last 100 projects. Its application criteria will need to be mastered and its interaction with other systems analyzed carefully. It will not have the track record that standard systems have, making the available reference literature less supportive and performance assumptions may need to be reevaluated.
CONSTRUCTION PERILSThe construction team must take the documents provided by the design team and produce a complete building with a myriad of functioning systems and sub-systems. Numerous highly skilled and experienced craftsmen and managers work together to make this happen. These individuals and their organizations are often trained and experienced with a variety of standard designs. Innovations will change the way the work is completed.
The individuals installing, starting, and testing new building systems and equipment have gained most of their training and experience with standard types and are less likely to be prepared for varying procedures.
DESIGN PHASEThe practice of commissioning has developed to provide quality assurance geared toward proper function of building systems and subsystems. Thus, it is suited to address many of the issues that come with accelerating the introduction of innovations to the building industry.
The commissioning provider's emphasis on functionality can make him an invaluable asset to the design team in maintaining and raising the level of quality of the design. The roles of owner's advocate and keeper of the design intent can provide perspective to help the application of innovations stay down to earth and connected with reality by reviewing documents with a skeptical eye and a system-wide perspective. Special attention should be given to all innovative systems and equipment to ensure they are selected and applied properly and with care.
CONSTRUCTION PHASEThe commissioning provider should consider raising awareness of the intent and nature of innovative systems and equipment among the construction team. Appropriateness of installation and startup plans should be ensured and may have to be developed virtually from scratch. A proactive approach of facilitating the awareness of unique installation and startup requirements including access to appropriate documentation will prove more effective than a more distant contractor-driven documentation review approach alone.
The accelerated adoption of innovative systems is critical to achieving the goals of the green building movement. By tailoring commissioning appropriately to the requirements of innovative systems, the risk to green building may be mitigated and overcome.
Adam Wheeler is the president of Sherrill Engineering Inc., San Francisco. He can be reached at 650-952-6466.
Publication date: 07/10/2006