Building commissioning (Cx) is the process of verifying, in new construction, all (or some, depending on scope) of the subsystems for mechanical (HVAC), plumbing, electrical, fire/life safety, building envelopes, interior systems (example laboratory units), co-generation, utility plants, sustainable systems, lighting, wastewater, controls, and building security to achieve the owner's project requirements as intended by the building owner and as designed by the building architects and engineers. Recommissioning is the methodical process of testing and adjusting the aforementioned systems in existing buildings.
Building commissioning is a quality-focused process necessary for both non-complex and complex modern construction projects. Normally the initial commissioning team and a team leader (typically known as the commissioning authority or CA) is involved from project initiation through one year of occupancy. In many cases and ideally, there is an ongoing building enhancing and commissioning program and team for the life of the building. While the service method can vary from owner to owner and project to project, the basic formula for a successful building commissioning process involves a synergy team from pre-design to develop the owner's project requirements (OPR), commissioning scope and plan, including benchmarks for success, review of design documents and checklists for achieving the Owner's Project Requirements (OPR), development of checklists and verifying a sample of construction checklists and submittals, developing training needs and evaluating training delivered by the contractors, witnessing and verifying construction phase tests, and periodic site observations during the construction phase, and performing commissioning functional testing as the project nears completion. While the practice of building commissioning process is still fairly new in the construction industry, it has quickly become common practice as building owners and developers try to get more out of their investment. The commissioning process main goal is to improve a project from the design phase through post construction and occupancy.
Video New-construction building commissioning
The commissioning authority or commissioning agent (CxA) is generally (and preferably) contracted directly to the building owner as a third-party independent representative to ensure unbiased performance of the CxA. The CxA may be (but not preferred) a subcontractor (or employee) of the building owner, architect, design engineer, test and balance contractor, or other trade contractor (i.e. HVAC/mechanical, electrical, Plumbing, fire protection, security, etc.) for specific trade testing. It is highly recommended by most industry experts and standards that the CxA be an independent third-party consultant directly contracted to the building owner, and reporting directly to the building owner. It is also highly recommended that the CxA be contracted early in the project planning stages, included in design charrettes, and maintained throughout the design, construction, and final acceptance of the project at a minimum. Having the CxA on the team early provides opportunity to identify possible operation, installation, testing, and performance issues long before they become a construction issue. The CxA works closely with the owner's representative, building/facility operating engineer, architect, design engineer, general contractor, and all trade subcontractors. The CxA typically is responsible for leading and managing the project commission process (design and/or construction) and works closely with the design, construction, and operation teams in a co-operative work environment that focuses on teamwork throughout the building's design, construction, and post construction.
A CxA's ability to add value to a project is rooted in their ability to create positive working relationships with all parties involved and not pointing fingers when issues arise. It is important that the CxA clearly identifies the communication processes/streams, the project goals and expectations (from the OPR), and the team member responsibilities. A CxA has to be able to give open constructive criticism while also being able to listen attentively. The CxA's primary goal is to provide a completed and properly operating product to the building owner and occupant/user.
The CxA's work and performance of service is equally or primarily in the background performing design, submittal, O&M Manual reviews and development of testing and commissioning processes for the project, as well as documenting the commissioning efforts. The CxA attends design and construction meetings, performs site construction observations, observes factory equipment testing, directs and observes functional performance testing of systems and equipment. The CxA typically does not actually perform the hands-on testing, as these are actually performed by the manufacturer, vendor, or trade contractors, and directed and observed by the CxA utilizing testing procedures and expected performance outcome previously identified by the CxA during the commissioning document development process.
The CxA typically prepares a commissioning specification and commissioning plan during the project design phase. The design engineer also may develop the commissioning specification (and rarely the commissioning plan) in situations where the CxA has not been so contracted, or brought into the design team during the design process. The commissioning plan is a live document that outlines the commissioning processes and expectation based on the Owner's OPR, the design engineer's basis of design (BOD) and the project construction document (drawings and specifications). The commissioning plan is modified as the commissioning process progresses throughout the design, construction, and final acceptance of the facility. The functional performance test procedures are typically developed by the CxA with assistance of the trade contractors, vendors, and manufacturers based on the design engineer's contract documents. These same parties and the design engineer, and owner's representative (typically the facility operating engineer) review the functional performance test procedures and expected outcomes prior to testing. The systems, equipment, items, processes, modes, and sequences of operations to be tested by the CxA (contractors or others) should be detailed and identified in the design engineer's construction documents (drawings and specifications), the construction request for proposal (RFP), the contractors bid submission, the commissioning specifications, the commissioning plan, and the contractors submittals. Of utmost importance, often neglected by contractors, are the equipment/systems "installation and operations manuals" (IOM or IO&M) "specific to the project" (not generic). The IOM's along with complete, and very detailed, sequence of operations (SOO) and control drawings/documents submittal "specific to the project" (not generic) are of utmost importance to the CxA to perform the review and develop proper testing procedures. Timely delivery of these documents to the CxA is important to facilitate the CxA ample time to review, develop test, obtain reviews, and implement changes prior to scheduling of any testing.
Maps New-construction building commissioning
Building management Systems (BMS) or Building Automation Systems (BAS)
Building management systems (BMS) or building automation systems (BAS) provide control of the building systems. These typically include heating, ventilating, air-conditioning and refrigeration (HVAC/R), electrical power, lighting, fire suppression and alarm, and security systems, etc. Building controls also have the ability to monitor and control systems to improve performance, conserve energy, conserve water, and control lighting. The greater control provides the ability to improve a buildings performance, environmental impact, and the user/occupant's environment. Direct digital controls (DDC) with real time monitoring and history provide the ability to acquire system data realtime or with trend-logging, or trending, (over a predetermined period of time) to observe performance, issues/troubles, and identify possible improvements to operations and maintenance.
Building systems and equipment (HVAC, electrical, etc.) operate via the control systems (BAS, BMS, and similar) based on a designed sequence of operations (SOO) typically developed by the design engineer (specification) and modified during the submittal process by the trade contractors (and reviewed and approved by the design engineer). This SOO is also reviewed by the CxA who utilizes the SOO to develop the functional performance test procedures. The functional performance test procedures are typically developed by the CxA with assistance of the trade contractors, vendors, and manufacturers, reviewed by same, and the design engineer. The systems, equipment, items, processes, modes, and sequences of operations to be tested by the CxA (contractors or others) should be detailed and identified in the design engineer's construction documents (drawings and specifications), the construction request for proposal (RFP), the contractors bid submission, and the commissioning specifications and commissioning plan. The commissioning specification and commissioning plan are typically developed by the CxA during the design phase of the project.
The CxA works closely with the controls contractor to verify the control programming and identifies corrective issues during reviews and the functional performance testing. By performing the functional performance testing it is often, if not always, found where there are difficiencies in the systems or control and identifies items for improvement. Each and every point and sequence is typically not required to be tested by the CxA. The contractors typically hold the responsibility of testing and verifying each and every point and sequence, and the CxA performs a test of a sample of the items after the contractors have tested, repaired and verified. Re-Testing of the same, or another sampling, by the CxA is often required to re-verify deficiencies identified during the initial testing.
The integrated operations and performance of the many building systems such as HVAC, life/fire safety, domestic water, power, CO2 ventilation, and similar provide a complex and important performance for the facility and its occupants. Functional performance testing to verify proper operation prior to occupancy it extremely important. Testing of existing facilities is performed similarly by re-commissioning (commissioning of a building/system/equipment that has been previously commissioned) and retro-commissioning (commissioning of an existing building/system/equipment that has not been previously commissioned). Assurance of performance and operation by the CxA's commissioning verification of the facility typically provides a better operating, performing, and comfortable environment for the owner and occupants.
System degradation
It is estimated by Texas A&M researchers that as much as 20% of the energy used in an average commercial building is waste associated with poorly operated systems.
Buildings systems underperform for several reasons:
- They were never properly configured
- The design did not account for all sources of building efficiency
- The building is not properly maintained
- The use of the building has changed over time
An "independent third-party commissioning agent" has been highly regarded as providing benefit to most every project. To provide any benefit, the facility, systems, and equipment must be thoroughly designed, submitted to, and approved by a responsible, thorough, professional architectural and engineering design team to function correctly. The design team incorporates the documented owner's program of requirements (OPR) which identifies the owner's systems, equipment, materials, control, and performance expectations. The design team identifies and documents the project basis of design (BOD) which specifically identifies the OPR items, how each was implemented in the design (or modified), and the final design basis for systems, equipment, materials, control, and performance expectations.
The fast-track nature of the design and construction process (experience in 2011) often leads to missed planning, design, and even construction items. Items missed during the design and construction process can often be identified by the CxA during development of the functional and performance test procedures or during functional and performance tests.
The commissioning team, led by the CxA, has a primary objective of verifying proper installation, operation, and performance based on the project design (BOD) and the OPR. The commissioning of the facility, systems, and/or equipment provides verification, identifies issues and discrepancies, and if designed and constructed properly, ultimately enhances the facility total quality, control, performance, and efficiency which in turn provides increased sustainability.
References
Sources
- http://www.bcxa.org/resources/pubs/index.htm
- ASHRAE Guideline 0
External links
- Building Commissioning Association
- AABC Commissioning Group (ACG)
- California Commissioning Collaborative
- National Conference on Building Commissioning
- Eastern Canadian Chapter
- National Environmental Balancing Bureau
Source of article : Wikipedia
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