Developing new skills can be an intimidating and difficult undertaking.
Very often we are our own worst enemies by making things that we are not familiar with more difficult than they actually are. Getting started and prioritizing important issues may well represent the largest hurdle on the path to broadening our talents.
With practice and experience, procedures become second nature. This has been our experience with the art of HVAC commissioning. Sometimes it is perplexing to hear questions from colleagues about the commissioning process that seem self evident to us. Herein lies the dilemma of teaching effectively; on the one hand good teachers know their subject matter intuitively, but at the same time they must communicate the basics clearly, and without assumptions. So let us see if together we can debunk some of the mystery surrounding the HVAC commissioning process.
The Foundations of Commissioning
HVAC commissioning is a specialty. As it turns out, many of the qualities, skills, talents, and experiences of test and balance professionals prepare them uniquely for the HVAC commissioning agent role. Unlike engineers and builders who spend months and years on individual projects, TAB personnel witness a varied and broad range of construction and design applications, including common problems both in installation and coordination. Combining these hard-earned skills with a consistent commissioning methodology forms the basis for an effective HVAC commissioning practice.
So what is the commissioning process? Neophytes may hold the belief that design engineering credentials or years of construction installation experience are necessary as a foundation for developing a commissioning process. While these are also effective avenues from which to approach commissioning, they are not mandatory – there's more than one way to skin a cat. The point is that commissioning is not designing or building the project. Commissioning is proactive verification of compatibility between construction activities and design intent. You don't have to understand the entire chemical composition of chocolate to determine whether or not the cake is chocolate flavored.
However, you do have to know what chocolate tastes like in order to taste it. Similarly, to commission effectively you must have the ability and experience to read the drawings and specifications – particularly control sequences – in order to render commissioning services.
TAB professionals do this every day on every project. Two vehicles form the foundation of the commissioning process. These are the commissioning team and the commissioning plan. No matter the delivery mechanism of commissioning services – whether it be independent, contractor, or design professional driven – successful commissioning contains these two elements. No single individual has the ability to ferret out every design and construction problem on a project. Selecting and motivating a commissioning team and supplying a clear commissioning plan in the spirit of cooperation and partnering can overcome the
shortfalls of individual people. That's it: commissioning team + commissioning plan = commissioning process!
The Team and the Plan
The HVAC commissioning team is defined in the AABC HVAC Commissioning Guideline :
• Owner
• End-user
• Architect
• Mechanical engineer
• Electrical engineer
• Commissioning agency
• General contractor (or construction manager)
• Mechanical contractor
• Electrical contractor
• Controls contractor
• Sheet metal contractor
• TAB agency
• Owner's O&M staff
Depending on project specifics, additions or subtractions from this list may be required. For example a manufacturer/ vendor may need to be on the commissioning team, or the owner and the end-user may be the same party. Now what about the commissioning plan? The commissioning plan starts with the request for proposal (RFP) response. In other words when a commissioning agency develops the scope on a project to price services, this becomes the basis of the commissioning plan. From this point forward the commissioning scope morphs into a commissioning plan that continues to evolve throughout the course of design, construction, acceptance and warranty period and beyond (as in continuous commissioning).
After developing the commissioning scope and marrying it with project-specific equipment and systems, obtaining project schedules and timelines becomes a necessity to price the project. One needs to know the number of phases and the completion date to estimate meetings, manpower commitments and sequences of commissioning activities. Breaking down the scope elements and combining them with timeline information results in a quotation and a crude commissioning plan.
From the perspective of a TAB firm, it is obvious that when quoting TAB services on a project employing commissioning, details of the commissioning plan must be made available to assess the required TAB involvement for accurate pricing. Even if a commissioning plan is not issued (and technically it should be before contractors are asked to prepare bids) a scope of commissioning services most likely exists from which to evaluate the TAB commitment.
A common fallacy is that HVAC commissioning involves extensive TAB involvement. In reality, most HVAC commissioning utilizes the TAB report as a tool for evaluating system performance, while requiring only a marginal amount of TAB verification on the order of selecting 10 percent of documented TAB data – a condition typically found in TAB specifications even when commissioning is not formally incorporated as a separate project trade. The heavy lifting on HVAC commissioned projects comes from the controls contractor, who must manipulatesystems to accommodate testing. The remainder of this article will present an HVAC commissioning scope of work and HVAC commissioning fee breakdown that lead to effective pricing and further development into an actual commissioning plan. In future articles we will demonstrate the "fleshing out" of this
scope into a more detailed and procedural commissioning plan. We will further explore the pre-design, design.
construction, acceptance, and post-acceptance phases and add the details needed to describe start-up, systems verifications checks, functional performance tests and O&M training.
Sample Commissioning Scope of Work:
1. Introduction
A. Commissioning Process
1) The purpose of the commissioning (Cx) process is to ensure that the building owner receives a functional, timely product that conforms to the Design Intent Document, and provides an accurate accounting of any deviations that do not meet those requirements.
B. Design Intent Document
1) The Design Intent Document (DID) represents a composite of design drawings, project specifications, submittals, change orders and industry standards which describe the HVAC systems of this facility.
References to design intent will be taken from these contract documents. The DID is an evolving manuscript maintained by the design professional to track and incorporate design alterations which occur throughout the construction process. Any industry
standards used for this project will be specifically noted when referenced.
C. Commissioning Team
1) The Commissioning Team (CT) shall consist of key parties involved in design, construction and testing of this facility. It is necessary for each agency to appoint team members that will have long-term commitments to this project. Switching team members during the project will reduce the ability of the CT to provide continuity and acceptable results to the building owner. Team members must maintain an ongoing supervisory position on this project. One team member shall be provided by each of the parties listed below:
(a) Engineering Services (ES)
(b) Design Engineer (DE)
(c) General Contractor (GC)
(d) Mechanical Contractor (MC)
(e) Controls Contractor (CC)
(f) Test and Balance Contractor (TABC)
(g) Electrical Contractor (EC)
(h) Commissioning Agent (CA)
2. Commissioning Process
A. Design Review
1) The Design Intent Document (DID) represents a composite of design drawings, project specifications, submittals, change orders, and industry standards which describe the HVAC systems of this facility. References to design intent will be taken from these contract documents. These documents will be reviewed with special attention to adherence of selected equipment to design intent, optimization of performance, accessibility, TAB provisions, and O&M considerations.
B. Kick-Off Meeting
1) A kick-off meeting will be scheduled early in the construction process. The meeting will primarily focus on scheduling issues and reviewing each commissioning team member's responsibilities. Members of the CT will be expected to attend this meeting.
C. Commissioning Meetings
1) Commissioning meetings will be held in conjunction with progress meetings as necessary. The CA will be on site for the Cx meetings. Commissioning meetings will be used to address any problems that alter the design intent or hinder the commissioning process. These meetings provide an open forum for exchange of ideas between contractors, vendors, designers, users and owners.
D. Resolution Tracking Forms (RTF)
1) Resolution tracking is a method employed by the CA to monitor and record problems, their causes, and solutions. The use of these lists prevents problems uncovered during commissioning from being forgotten, and expedites their resolution. The use of RTF's helps ensure that problems or questions will be resolved in a timely manner.
E. System Verification Checklists (SVC) / Manufacturer's Checklists
1) The CA will review the SVC for each piece of equipment prior to start-up. Equipment will be released for start-up only after these checklists have been completed by the installing contractor and reviewed by the CA.
2) The equipment manufacturers' checklists must also be reviewed by the CA prior to start-up. These lists must be completed by the installing contractor, and reviewed by the CA before start-up can commence.
F. Start-up
1) CT members involved in installation, fabrication, manufacture, control, or design of equipment are required to be present at the time of start-up. A factory-authorized technician will be on site to start equipment when required by the specifications. This
will minimize delays in bringing equipment on line & expedite acceptable functional performance in accordance with the DID.
G. Controls / TAB Monitoring
1) Close monitoring of the Control Contractor's progress will promote efficient coordination of the TAB work. The CC will be expected to submit point by point checklists verifying that his work has been completed and all systems are ready for TAB work
and Functional Performance Testing. Programming and graphics will be surveyed by the CA for completeness and conformance with the DID and the owner's scheduling requirements.
2) TAB work will be monitored so that any problems that prevent or hinder proper air and water balance can be addressed and corrected with minimal delays. By addressing these problems as quickly as possible, we can ensure that functional performance testing and owner training will take place on schedule.
H. Functional Performance Tests (FPT)
1) The functional performance tests shall include all HVAC and related equipment.
(a) AHUs will be tested in designed operating modes. Proper operation will be verified at minimum OA, maximum OA, automatic control, and other modes, if necessary, to achieve DID conformance.
(b) VAVs will be tested at minimum and maximum airflow setpoints, and under automatic control. Intermediate settings will be tested as necessary.
(c) Exhaust fans will be tested for conformance to DID.
(d) Hot water pumps will be tested at under relevant operating conditions.
(e) Hot water coils will be tested under relevant operating conditions.
(f) Temperature control devices will be tested at maximum heating and maximum cooling conditions, and under automatic control. Intermediate settings will be tested as necessary to achieve DID conformance.
(g) HVAC systems will be tested to ensure that the building as an integrated system operates properly.
I. Building Turn-Over / Owner Orientation / User Training
1) The CA will assist contractors prepare, coordinate and review operation and maintenance (O&M) manuals, working closely with each contractor to achieve specificity and completeness.
2) The CA will review as-built drawings, working closely with each contractor to achieve specificity and completeness.
3) The CA will coordinate and facilitate owner orientation and user training in conjunction with specified allotted hours for each applicable contractor and subcontractor in order to deliver to the owner/user adequate training and information needed to properly operate and maintain the HVAC systems. The commissioning agent will make himself available for questions and problems the owner/user encounters during the initial occupancy of the facility. We recommend contacting the CA with post construction difficulties in order to efficiently direct problems to the appropriate contractors.
4) The CA will assist the owner/user with warranty issues.
5) The CA will coordinate and facilitate off-season testing, calibrating, and servicing as specified in the contract documents.
3. Conclusion
A. HVAC Commissioning aspires to provide the owner with an added level of confidence that the design object tives set forth for this facility integrate features commensurate with the best interests of the university's plans as set forth in DID. An unbiased commissioning team approach augments the efforts of the design and construction teams to deliver a facility that meets the owner's HVAC Engineering Standards and Performance Specifications, as well as usage requirements.
Sample HVAC Commissioning Scope Breakdown
1. Design Review The Design Intent Document (DID) represents a composite
of design drawings, project specifications, submittals,
change orders, and industry standards which describe the
HVAC systems of this project. References to design intent
will be taken from these contract documents. These documents will be reviewed with special attention to adherence of selected equipment to design intent, optimization of performance, accessibility, TAB provisions, and O&M considerations.
2. System Verification Checklists (SVC)
[CA] will write SVC's based on the DID. These checklists will be created for HVAC systems and subsystems. This includes, but is not limited to, Air Handling Units, Variable Air Volume Boxes, Unit/Cabinet Heaters, Perimeter Heating, Exhaust Fans, HVAC Pumps, and Boilers. Draft copies will be submitted to the DE and the Contractors for review and comments prior to placement on the job site. These SVCs will be bound in a three-ring binder and placed on the job site for use by the installing
contractors. No system will be started until the appropriate SVC's have been completed.
3. Functional Performance Tests (FPT)
[CA] will write FPT's based on the DID. These tests will be created for HVAC systems and subsystems. This includes, but is not limited to, Air Handling Units, Variable Air Volume Boxes, Unit/Cabinet Heaters, Perimeter Heating, Exhaust Fans, HVAC Pumps, and Boilers.
4. Manufacturer's Pre-Start Checklists / Start-Up
Procedures
The manufacturers pre-start checklists and start-up procedures will be supplied by the installing contractors to [CA]. These lists will be included in the thee-ring binder along with the SVC's for use by the installing contractor.
5. Preliminary TAB Review
The preliminary TAB report set-up will be reviewed prior to HVAC equipment start-up, in order to ensure that the final TAB report format and content is acceptable.
6. HVAC Equipment Start-Up
Start-up of major HVAC systems will be witnessed by [CA]. The appropriate contractors and/or manufacturer's representative will be required on site to perform start-up. No system will be started until the appropriate SVC's have been completed. No system will be started until the Manufacturer's checklists have been completed. Start-up will be performed according to the Manufacturer's recommended procedures. [CA] will visit the site to review completeness of installation in conjunction with progress meetings prior to starting HVAC equipment.
7. TAB Review
A pencil copy of the TAB report will be reviewed prior to submission of the final TAB report. A written review will be submitted to the TAB contractor and to the DE for their comments. An acceptable TAB report will be required before Functional Performance Testing can be carried out. [CA] will visit the site during the TAB process in order to assist TABC and CC in the effective completion of their scope of work.
8. Functional Performance Testing
Each major system will be tested. A random sample of each subsystem will be tested. This will be coordinated and witnessed by an [CA] representative and the owner's maintenance staff. Witnessing the FPTs will constitute part of the O&M Training. No FPTs will be performed until the system and related subsystems have been started, the TAB work has been completed, and the TAB report has been submitted and reviewed.
9. Building Turn-Over / O&M Training
Owner training will be coordinated through [CA]. The training will be provided by the installing contractor, or manufacturer's representative, and witnessed by [CA]. This training should include both classroom training and hands-on operational training. The owner may choose to video tape this training for future use. [CA] will visit the site during the Turn-Over and Training period to ensure that any on-going HVAC related problems are being addressed and corrected in a timely and efficient manner.
Conclusion
Please note that our fee is based on the assumption that [CA] will not make regular site visits or attend progress meetings until substantial amounts of HVAC equipment have been installed. It should also be noted that the installing contractor will be responsible for completion of the SVCs and the Manufacturer's Pre-Start checklists. We would also request that progress meeting minutes be forwarded for our records. Two meetings are implicitly included in the above pricing. One "Commissioning Kick- Off Meeting" would be provided to acquaint the contractors with the HVAC Commissioning process and their role in that process. One additional meeting would be provided just prior to start-up to review the process and procedures. Our pricing includes time for Start-up and Functional Performance Testing for a single-phase project.
Sample HVAC Commissioning Fee Breakdown:
1. Design Review .
2. System Verification Checklists (SVC) .
3. Functional Performance Tests (FPT) .
4. Manufacturer's Pre-Start Checklists / Start-up Procedures .
5. Preliminary TAB Review .
6. HVAC Equipment Start-Up .
7. TAB Review .
8. Functional Performance Testing .
9. Building Turn-Over / O&M Training .
10. Meetings & Site Reviews .
11. Resolution Tracking Forms (RTF) .
Total Commissioning Cost .
[Note: items 10 & 11 can be incorporated into items 1 thru 9, above, or itemized separately – cost breakdowns should be developed to suit business practices.]
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