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A CASE STUDY: COST IMPLICATIONS FOR HVAC COMMISSIONING Julie Seelen James E. Woods, P.E. John J. Harmon, P.E. Member ASHRAE Fellow ASHRAE Life-Member ASHRAE ABSTRACT The use of formal commissioning processes for HVAC systems has recently increased 1 in the United States. The prime objective of commissioning is to verify that the HVAC systems function as intended by the original design. The documentation and operator training, also included in the commissioning, should result in a better understanding of the systems and therefore better operation and maintenance practices. This could result in increased assurance of delivering a healthy building. Although little quantitative evidence exists, it is generally assumed that this process is cost-effective. To study its effectiveness, a commissioning process has been instituted' for a small new research facility. Eight bids were received for this project and'the anticipated cost for the contractor's participation in the commissioning ranged' from 0% to 2% increase of the base bid. A follow-up survey with the eight bidders of the project revealed that none of them had' experience with the commissioning process. The total cost of commissioning including fee for the commissioning authority was approximately 2.5% of the total project budget. No identifiable cost avoidances were detected during the construction phase, primarily due to the owner's inexperience with this process. However, substantial cost avoidance was realized during acceptance and post-acceptance phase estimated for the first year at 50% of the commissioning cost. Recommendations are given on additional commitments required from owner, designers and contractors to realize the potential of the commissioning process. J. ee en, eseare ssocaa e: J.E. oo .s, .i iam E. amerson r ro essor o ui mg Construction: Indoor Environment Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; J.J. Harmon, Senior Vice President HC Yu and Associates, Consulting Engineers, Richmond, Virginia.

INTRODUCTION The purpose of the commissioning process, as proposed in the guideline from ASHRAE (ASHRAE 1989, Lawson 1991) is threefold: 1. To verify operation and functional performance of the HVAC systems for compliance with the design intent. 2. To document the design, the construction requirements including test-inspections,Test And Balancing reports (TAB), warranties, and as-builts, and to review the operation and maintenance manuals. 3. To train personnel for operation and maintenance of the HVAC equipment and systems. Although most of these procedures are presumed to be included in the responsibilities of the players in the construction process, they are not always executed. Formalizing these procedures and adding an overall performance verification maximizes the assurance for the owner that he will receive an adequately working HVAC system (Elovitz 1992). The commissioning process typically involves the design engineer, the contractor, the building owner, and the commissioning authority (CA). However, there is no consensus that anyone of these participants has a mandate to serve as the commissioning authority (FCC 1992). The design engineer, who is responsible for the design of a HVAC system that meets the criteria set forth by the owner, may be best equipped to verify system performance according to design intent but may have a potential conflict of interest. The contractor, who is responsible for the construction and deliverance of a working system, may be best equipped to train the personnel in operation and maintenance but may not understand the design intent. Other possible sources of commissioning authorities include TAB firms, independent architect/engineering firms, and the building owner.

Although little quantitative evidence exists, it is generally assumed that this process is cost-effective. The process, when initiated at the pre-design phase, has the potential to detect areas of conflict in the design and may prevent costiy change orders. During the construction and acceptance phase the owner will have a better chance of getting a system performing to meet his requirements without exceeding the budget or time schedule. This has been demonstrated in several cases in Canada (Trueman 1989). Instituting the commissioning in Maryland resulted in shorter punch-lists, improvement of the overall quality of the projects, better training, and no claims or overruns so far (Edwards 1993). The training of operation and maintenance personnel and the documentation should result in a better understanding of the systems and therefore better O&M practices. The entire process should result in increased assurance of delivering and maintaining a healthy building. This paper reports the findings of a case study where a commissioning process was Instituted during the pre-design phase of a new research facility. The cost-effectiveness of the commissioning process is evaluated and recommendations for future specifications are provided. THE CASE: A NEW RESEARCH AND DEMONSTRATION FACILITY The Research and Demonstration Facility (RDF) grew out of the need to investigate issues related to the evaluation and influence of indoor environment on human responses at full-scale. The intent of this facility is twofold: 1. To investigate systems that control exposure to four stressors, i.e., thermal, lighting, air quality and acoustic; and to satisfy criteria which qualify a building to be a healthy building. 2. To demonstrate innovative building systems.

The primary focus of the initial research is an evaluation and comparison of two HVAC systems, i.e., variable air volume and vertical displacement, for thermal, air quality and economic performance. Because the work that will be done at RDF represents an on-going research agenda evolving over time, the building must respond as a dynamic and reconfigurable research laboratory. Therefore, a column-supported space frame with a masonry infill at the perimeter that allows for the expansion or reconfiguration of the enclosure system was chosen. The space frame provides an interstitial space which accommodates duct runs, mechanical equipment, lighting systems, and data communication equipment. The facility accommodates two large office areas of 700 square feet each, a conference room (200 sq ft), an instrumentation room (250 sq ft), and a mechanical room (1240 sq ft). The two offices appear identical but the HVAC systems are different. One office is served by a conventional VAV system with ceiling supply and a ceiling plenum return. The other office is served by a vertical displacement system with supply air via a sub-floor plenum through a perforated' floor/carpet. The return air in this office passes through the grilles in the ceiling and is ducted back to the air handling unit. A third air handling unit, with 100% outdoor air, serves the conference room, corridors and instrumentation room. A more detailed description of this facility was reported in Schubert et al., 1992. Because the mechanical systems are a critical component of this facility, the commissioning process was instituted to: 1. Ensure that the systems function according to their design intent. 2. Minimize the delay in start-up time. 3. Evaluate the commissioning process and its cost-effectiveness. The design engineers of the systems were retained as the commissioning authority. The others involved are the contractor and his mechanical sub-contractor, the TAB-agency,

the owner, the manufacturer and installer of the Direct Digital Control-system (DDC), and the research group who is the future user of the facility. The research group also serves as the evaluator of the procurement process and life cycle cost of the facility. The responsibilities of the owner, contractor, commissioning authority, and design engineer were outlined in the bid documents (See appendix A). As the DDC-system was provided under a separate agreement with the owner, the responsibilities of this co.ntractor were not defined in these bid documents. Although the design engineer was retained by the owner as the commissioning authority, the cost for their participation in the commissioning process was negotiated separately from the cost for design. COST IMPLICATIONS Pre-design and Design Phase During the pre-design phase, the HVAC commissioning parameters and frame-work were set up. The owner also defined the building program. In the design phase, the commissioning process was specified and included in the contract documents (Appendix A). As the contractors likely to bid the project were inexperienced with commissioning, the process was further explained at the pre-bid meeting. The commissioning plan, detailing the implementation of the commissioning process and the testing protocol was not part of the contract documents but was released during the construction phase. The extra cost for the design engineer to specify the commissioning process and meet the requirements as specified therein added less than 2% to the overall cost for the engineering design. The total cost for the commissioning by the design engineer as the commissioning authority added 14% to the total architect and engineering fees for this small, (i.e., 1850 sq ft of net occupiable space) complex facility (i.e., research facility with three

independent, different HVAC systems). A potential cost increase, that did not occur in this project, was the increase due to changes the design engineer might have been required to make per directions from an independent commissioning authority. Construction Phase Initial construction cost-To obtain information on the cost for the general contractor to participate in the commissioning process, it was included as an add-alternate item in the bid documents. Eight bids were received and the add-aitemates ranged from 0% to 2% increase of the base bid (See Table 1). A follow-up survey was conducted and all contractors and their sub-contractors were interviewed. None of the eight general contractors had any experience with the commissioning process. Most general contractors used the quote from the mechanical subcontractor as the bid-price for the add-aitemate. Some added an additional administration cost. The bidder, lowest for the base bid and the total bid, reduced the quote for the commissioning by 22% after the pre-bid' meeting, where some clarifications to the specifications were made. One bidder felt that commissioning added cost that could be justified for this facility only because it was a research facility. Including the commissioning process in the bid documents caused some mechanical contractors not to bid the project. Most mechanical bidders misunderstood the scope of the work and were not clear on their liability. Not all bidders attended the pre-bid conference. One of the mechanical bidders intended to hire an engineering firm as the Commissioning Authority, although the specifications clearly stated that the owner would engage the CA. ~ N None of the mechanical bidders had experience with the commissioning process or were 0A familiar with the ASHRAE GP-1 (ASHRAE 1989). ~ ~ m The actual cost for the genwral contractor to participate in the commissioning was 1.4% N

increase of the base bid price or 6.6% increase of the cost for mechanical and plumbing bid for this small, complex facility. Change ordets- More than thirty RFP's (Request For Price) were issued on this project, one third related to the HVAC systems. According to the owner's representative, this is not an unusual number of changes for projects like this, but according to the general contractor this number is high for a project of this cost. Compared to recognizing and correcting these changes during design the increase of the total construction price due to the change-orders involving the HVAC systems was estimated at less than 1% of the project base bid. A goal for the commissioning process should be to eliminate all incremental cost due to change orders. Completion on time- Substantial completion was reached six and a half weeks after the original schedule. Two weeks of the time-delay was weather-related, two weeks delay was due to miscommunication on start-dates, one week was due to contractor delay. One and a half weeks was due to change-orders related to the HVAC systems. If these change- orders would have been prevented, the one and a half weeks time delay would not have occurred. This was delay in productive occupancy for this facility, a cost that may have been avoided. Another goal for the commissioning process should be to eliminate all time extensions to the change orders. Acceptance Phase and Post-acceptance Phase During the acceptance phase, the training of operation and maintenance personnel was carried out in addition to the verification of system installation and functional performance. The initial training of O&M personnel was done in one day and included three parts. First, the design engineer explained the intent of the system design. Second, the mechanical sub- contractor presented the equipment, operation and maintenance requirements. The last part

was a walk-thru of the building. The training on the control system was set for a later date. Participating O&M personnel were very appreciative of the fact that the design intent of the systems, explained by the design engineer, was also included in the training session. The commissioning authority verified the performance of the systems, as outlined in ASHRAE GP-1, with help of the mechanical contractor. The performance verification of the waterside of the HVAC systems detected four items that were not functioning correctly, i.e. three items pertaining to boiler operation and one pertaining to chiller operation. These items were corrected immediately or during the week following the verification. Correcting these items before final completion avoided energy and O&M costs that would have occurred due to inappropriate capacity control. The performance verification of the airside of HVAC systems detected these malfunctions: one pertaining to draining and condensate pans, one pertaining to problems with air balance, and one pertaining to problems with control stability. Without commissioning, these problems may not have appeared for several months of operation and would have resulted in avoidable O&M costs to investigate and avoidable loss of productive research time. As the HVAC systems are the subject of research in this facility, the use of the commissioning process to assure that the systems are working per design intent at final completion also assures that the research can start immediately after final completion, and save valuable start-up time. CONCLUSIONS AND RECOMMENDATIONS The total cost for commissioning, including cost for the commissioning authority and ~y ~ the cost for the contractor to participate in the commissioning process, was approximately ~ 2.5% of the total project budget of this small, complex project. Because of the small complex ~ ~ scale of this project, we conclude that the 2.5% cost may be considered a limit and that larger ~ ~

projects of similar or less complexity can be commissioned for a smaller percentage of total project budget. No identifiable cost avoidances were detected during the construction phase, primarily due to the owner's inexperience with this process. However, it is anticipated that cost avoidances during construction will be realized by the owners on subsequent projects by continuing to use the commissioning process. Substantial cost avoidance was realized during the acceptance phase and post- acceptance phase by: 1. Assuring that design intent was met at time of final completion assuring that the research agenda could be initiated. 2. Preventing energy waste due to detection of inappropriate capacity control of boiler and chiller. 3. Preventing unnecessary on-site visits by O&M personnel to trouble shoot the system. 4. Reducing unnecessary loss of productive research time due to system malfunctions. We therefore conclude from an analysis of the projected cost that the cost avoidance accrued during the first year will amount to approximately 50%a of the commissioning cost. This case study provides strong evidence that the commissioning process can be cost- effective. However, to realize its potential, additional commitments are required from the owner, designers and contractors: 1. Although in this case study, the bid documents clearly defined the roles and responsibilities, several bidders misunderstood the scope of the work. Therefore, the bid documents should not only define the roles and responsibilities of the different participants, but also include the commissioning plan in order to give the bidders a better idea of expectations and the work effort involved. 2. Attending the pre-bid meeting should be mandatory, and should include a

discussionlexplanation of the commissioning process. 3. At the pre-construction meeting a cpm-schedule (critical path method) for construction and commissioning should be agreed upon. 4. All parties to the commissioning process must be present during the final verification and training periods. ACKNOWLEDGEMENTS We recognize and thank the following people and organizations: H.G. Bumley, Jr. and C. Hayward of Philip Morris USA; J. D. Wenger and E. C. Emerson of Johnson Controls; A. J. Davis, architect of record, and W. Galloway and R.P. Schubert for assisting in the design process (College of Architecture and Urban Studies); J. G. Kuykendall and S. P. Warren of Facilities Planning and Construction at Virginia Tech; N. I. Broocke, H. G. Shirley, and R. F. Peroe for their cooperation in the Department of Engineering and Buildings (Commonwealth of Virginia); P. LeRoy and J. Lilly of Breakell Inc., and H. T. Cothran of G. J. Hopkins, Inc., and all other contractors who participated in the construction andlor follow-up study. REFERENCES ASHRAE. 1989. ASHRAE Guideline 1-1989, Guideline for Commissioning of HVAC Systems. Atlanta: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. Edwards F. C. 1993. Integration of commissioning into construction quality control program. Seminar Presentation at ASHRAE Winter Meeting in Chicago, 1993. Elovitz, K.M. 1992. Commissioning building mechanical systems. ASHRAE Transactions. Vol. 98, Part 2, pp.543-552. FCC: Federal Construction Council. 1992. Commissioning mechanical and electrical systems in buildings (Summary of a symposium). Technical Report No. 114. Washington D.C.: Building Research Board of the National Research Council. Lawson, C. N. 1991. Documentation of the commissioning process. ASHRAE Transactions,. Vol. 97, Part 1, pp.765-772. Schubert, R. P.; J. Seelen; J. E. Woods; and S. Arora. 1992. Design and construction of a facility for research and demonstration of healthy building concepts. Proceedings of the AIA Symposium: Designing for Healthy Buildings. Los Angeles, November, 1992. Trueman, C. S. 1989. Commissioning: An owner's approach for effective operations. ASHRAE Transactions, Vol. 95, Part 1, pp.895-899.