Opening Night.
The date is fast approaching. The new theater has a firm deadline for construction to be complete. The first performance is scheduled and tickets are sold. Everyone is scrambling to complete construction. The HVAC system is in place, and the controls subcontractor programs the system so that it can operate properly. Everything appears ready. On opening night, the audience enters the theater and fills every seat. Thirty minutes later, the theater is hot. People are uncomfortable. A wonderful performance by the actors anad by the other building systems is marred by the HVAC system. Why did this happen? Whose fault is it? What does this have to do with Commissioning?
It's nobody's fault!
The design engineer did not cause the problem. The right system is in place. The system is sized correctly. The HVAC contractor did not cause the problem. The installation is of very high quality. The ductwork and piping is installed with great care to deliver the cooling quietly and efficiently. The controls subcontractor did just what the documents called for. The control sequence reads "On a call for cooling (when the space temperature exceeds the desired cooling setpoint), the chilled water control valve shall open." This is exactly what was programmed.
What happened?
The controls subcontractor programmed the chilled water valve to take 15 minutes to open. For many buildings, this works well and avoids overshooting, which can result in poor control. For a theater, however, where the space can experience a change from minimum load to maximum load in 5 minutes, the valve needs to fully open much faster, in one minute or less. The initial programming resulted in the "hot" space temperature because the cooling equipment responded too slowly. After the performance, the system was analyzed. After much discussion between the owner, the contractor and the engineer, the culprit was found. The correction, increasing the speed of action of the chilled water control valve, was very simple to implement. At the next performance, the system worked beautifully, maintaining the conditions in such a way that the attention of the audience was given totally to the performance.
What does this have to do with Building Commissioning?
Building Commissioning could have prevented the opening night problem. The Commissioning Agent would have reviewed the temperature controls programming, and observed the testing prior to the first performance. The HVAC system designer's intentions for performance goals and load characteristics would have been documented and understood by the Commissioning Agent (or, as in many cases, the Commissioning Agent would have been the design engineer). As an informed observer, he would have bridged the gap between designer and contractor. It is highly likely that the opening performance would have been comfortable, thereby avoiding the negative experience that will linger in the minds of the audience.
Bridging the gap
This is a good way to sum up what Commissioning does. As in the above incident, which is a true story, the Commissioning Agent (Cx is shorthand for this) bridges the gap between the designer and the contractor. Even complete and very detailed construction documents don't relay all of the thought that is in the designer's head. The reasons for the system selection; how the system should be operated; what were the design parameters and goals; these are all examples of very useful information that is not a part of construction documents, but that when communicated to other members of the building team, can result in a successful installation for everyone. Commissioning bridges the gap not only between the designer and the contractor, but also between the owner and designer, the owner and the contractor, the designer and the owner's maintenance staff, and the contractor and the maintenance staff.
Building Commissioning: What is it?
One Cx described Building Commissioning in this way: "Don't believe anything anyone tells you. Check it out." Another description is defined by a goal: "Have zero items on the deficiencies and omissions ("punch") list." Both of these capture important elements of Commissioning, but don't tell the whole story.
Commissioning is a quality assurance process for the installation of the systems in a building. It is a process for achieving, verifying, and documenting the performance of each system to meet the operational needs of the building within the capabilities of the documented design and specified equipment capacities, according to the owner's functional criteria. It is a process that ensures the quality of the installation. Successful Commissioning includes the preparation of manuals and training of operation and maintenance personnel. The result of Commissioning should be fully functional systems that can be properly operated and maintained throughout the useful life of the building.
The major phases of Commissioning are:
The Acceptance Commissioning phase includes verifying accuracy of the final TAB report, verifying and documenting that all systems comply with the contract documents, verifying functional performance testing of all systems, establishing as-delivered performance record for all systems, verifying completion of the as-built records, conducting operations and maintenance personnel training, completing the final Commissioning report, completing the systems manaul and turning over all documents. The objective of the O&M training program (5) is to provide qualified technicians with the knowledge to operate and maintain building systems in accordance with the design intent, manufacturers' recommendations, and procedures contained in the systems manual.
Finally, the Post-acceptance Commissioning (6) includes ongoing Commissioning activities such as monthly monitoring of the control systems operation, minor changes or modifications to systems and changes to occupancy or layout, major modifications to the facility's layout or systems.
Owners may implement the Commissioning process at any stage of a project. However, the Commissioning process is most effective when started early.
Currently, other systems are being incorporated in the the Commissioning process. Sprinkler and fire protection systems, electrical systems, emergency power systems are now commonly being commissionined. Newcomers to the Commissioning process include building envelopes, doors, door hardware, door electronics, and security systems.
The cost of Commissioning fees is offset in savings due to many factors, including fewer maintenance calls, avoiding chronic problems, more efficient operation of building systems, and better maintenance resulting in longer life for the building systems. Contractors who have been a part of a succesfully Commissioned project are sold quickly on the cost savings of having no or very few "call-backs" during the first year of operation.
In conclusion, the goal of the Building Commissioning process is to turn over a building to the owner on "opening night" that is not only properly installed, but is functioning at an optimum level, and to give the owner the knowledge and tools needed to maintain this optimum level for the life of the building.
Posted July 2, 2003