Starting Commissioning During Design to Save Time, Money, and Energy

The building industry has come to appreciate the value of commissioning as a part of the construction process, helping to ensure the proper installation and operation of building components. The value of commissioning is not always apparent to building owners since it is a fair assumption that equipment should be properly specified and installed as part of the standard construction process. Commissioning has proved its worth because that assumption is often false, costing builders and owners money and wasting energy.

The lessons learned from construction-based commissioning are now being applied to the building design process. Starting the commissioning process during the design phase allows a project team to catch problems early and reduces rework. It is always cheaper to address a deficiency on paper than it is in the field.

Figure 1 - Design-Phase Commissioning: In Action
Commissioning agents proactively analyze building plans to detect possible problems for building operations early in the design process (click to enlarge).

While architects and engineers are supposed to put together an error-free design, that goal is rarely achieved. Design-phase commissioning brings a fresh set of eyes to a set of plans and analyzes the plans based on problems that are reasonably likely to arise from a building's operations. A good commissioning agent does not just look at the static systems but specifically focuses on hypothetical scenarios. Preparing for potential problems is an effective way to ensure a successful project. Items like extreme weather condit ions, poor staff training, loss of power, mechanical failure, and time scheduling are all topics that a commissioning agent should review when performing design-phase commissioning.

During the design phase, designers and engineers usually work under a tight budget with limited time to check their work, particularly with all other disciplines in mind. A commissioning agent reviews the work of the designers and engineers as a whole, with a budget that is specifically dedicated to the review process. If issues are discovered, the commissioning agents and the responsible party communicate to find a solution.

All issues resolved in the design phase will aid in making the rest of the project run smoother. As a project matures new issues develop through each phase. If the project team does not address each issue promptly, issues will accumulate and can become overwhelming by the post-occupancy phase. Such issues can result in litigation in the post-occupancy phase to determine who will fix building deficiencies. Commissioning can resolve those issues before they escalate.

Commissioning at the Design Review Phase

Any deficiencies or miscalculations have a greater chance of being discovered with multiple parties analyzing and discussing the design documents. Examples of items that might be identified for correction in design-phase commissioning include: Duplicate equipment identification numbers or "tag numbers" that need to be addressed to avoid confusion and missing equipment. Project team members identify all units by their specific "Tag Number" and when they are duplicated only one of the units may be installed when two or more are needed. Heat pumps should not be used to condition computer equipment because when heat pumps fail they can lock into the heating mode. The temperature of the computer room could then rise to a level that could damage the equipment. Ensure appropriate distances and directions between exhaust and intake vents to maintain indoor air quality. Confirm that maintenance access is provided for all units. For example, heating and cooling coils should be separated for easy maintenance.

Confirm that the equipment listed in the design documents are of high efficiency. Review Therma-Fuser™ and other VAV diffuser designs for constant supply pressure to the unit. Performance will suffer if supplied with variable pressure. Confirm that all systems are complete and contain the necessary equipment. Does the domestic hot water system have all pumps and valves needed? Does the lighting system show all occupancy sensors? Provide a sequence of operations or, if necessary, add greater detail to the current sequence of operation. Confirm all interlocks are noted. Confirm the design flow of the natural ventilation system and all controls. Confirm that all areas will be conditioned and that there are no missing units. Economizers must have all necessary dampers. Verify that all equipment highlighted in the drawing details match the schedule. Confirm what units are heating only or cooling only. Verify that no units are unaccounted for. Units that are to be removed or demolished are sometimes found on the drawings for new work.

 

Optimum building performance is another benefit of design-phase commissioning. Commissioning agents review the equipment designed for the building and the ideal operation of the chosen units. Equipment sizing, proper building management systems, and unit installation are just some of the aspects that commissioning covers to ensure building efficiency and energy cost savings.

The benefits of design-phase commissioning can be seen throughout a project's lifecycle. Once the design phase is complete, the commissioning agents are familiar with the project and are integrated with the project team. This allows better communication throughout the rest of the project and saves valuable time. With everyone working together from an earlier phase, it is much easier for the commissioning agents to get the project team to complete and return the Pre-Functional Checklists and Test and Balance Reports when it is time to complete the standard commissioning. The Sequence of Operations and Functional Performance Tests can also be more easily finalized. There will also be a higher level of builder participation when completing the Functional Performance Tests, resolving any issues discovered during the testing.

The Commissioning Plan and Specifications

A commissioning plan provides direction for the commissioning process throughout the project lifecycle. For any commissioning project to be successful, all the players must understand their roles and responsibilities. In the commissioning plan the commissioning purpose, goals, and LEED or other rating system are all explained. Project systems to be commissioned, building information as well as the project team information are listed. The commissioning process is then broken down and explained through the design, construction, acceptance, and occupancy phases. Scheduling is outlined and listed to keep a tentative outlook of when commissioning activities will occur. The commissioning plan is just another tool for the project to run smoothly and allow for full integration of commissioning services.

Commissioning specifications describe the requirements for the commissioned systems, subsystems, and equipment. Coordination and lines of communication are explained as well as the commissioning process and activities. As in the commissioning plan there is an in-depth description of the project team roles and responsibilities organized by title and project phase. Units and systems that are included in the commissioning scope are listed. Commissioning deliverables include:

• Submittal Review (Design Phase)
• LEED Documentation
• Pre-functional Checklists
• Post-Occupancy Review
• Deficiency Report with Resolution Recommendations
• Systems Manual
• Final Commissioning Report
• Personnel Training Review

Commissioning Studies

Lawrence Berkeley National Laboratory has an extensive database of the results of building commissioning. As of 2009, the study included 643 buildings with a cumulative size of 100 million square feet. The median cost for commissioning the buildings was $1.16 per square foot for new construction, 0.4% of total construction costs. The commissioning resulted in median energy savings of 13% for new construction projects. The study states "it is critical that commissioning be well integrated with the rest of the building lifecycle and associated services. These include design and design-intent documentation at the early stages of the project cycle." When commissioning is able to begin during the design phase the entire project will prosper.

The Division of Facilities and Services of Montgomery County, Maryland commissioned approximately ten of their projects. Design-phase commissioning significantly reduced the number of corrections required later in the construction process. The reduction in mechanical and electrical change orders and claims are estimated to have saved $1.57 per square foot on two projects alone. The division also estimated another $0.48 per square foot of energy savings the first year. The occupants also benefited by being able to move in sooner with a large decrease in post-occupancy issues. Design-phase commissioning saved time, money, and increased occupant comfort.

Design-Phase Commissioning in LEED

Commissioning is a systematic process of ensuring that the building systems perform according to the design intent and the owner's operational requirements. Under LEED Guidelines, design-phase commissioning is required for both Prerequisite and Enhanced Commissioning credits (EAp1 and EAc3). LEED NC v2.2 states that "the CxA shall conduct, at a minimum, one commissioning design review of the Owner's Project Requirements (OPR), Basis of Design (BOD), and design documents". To satisfy the LEED requirements a Design Review, Cx Plan and Cx Specifications are created to evaluate what the building is designed to do and how the design will be implemented. The Commissioning Agents will analyze all details looking for any potential project issues to lower the project lifecycle and cost.

 

 

Training Highlights

California utilities offer outstanding educational opportunities that focus on the design, construction and operation of energy-efficient buildings. Listed here are a few of the many upcoming classes and events; for complete schedules, visit each utility's website. System Diagram Workshop Most definitions of commissioning indicate in one way or another that it is an integration process that starts during design and persists throughout the building's or system's life cycle. The reason that system diagrams are such a powerful commissioning tool is because they integrate the system components into a single document; diagrams form a powerful basis for design early in a system's life and continue to serve the commissioning process by supporting the training and diagnostics that occur as the system is fabricated and operated. October 19 (Tuesday), 8:30 am to 4:30 pm, Pacific Energy Center, San Francisco register >

Control Systems: Design, Performance, and Commissioning Issues Control systems are the brains of our HVAC processes. Combine well selected, high quality, high efficiency equipment with quality control hardware and a well thought-out, well conveyed and well implemented control sequence and you will have a system that purrs along delivering the intended performance. December 7 (Tuesday), 8:30 am to 4:30 pm, Pacific Energy Center, San Francisco register > HVAC System Testing for Energy Efficiency Facility engineers, energy management, owners/managers of small-to-large businesses, and others who are interested in field testing and data acquisition instruments will learn how to maintain HVAC peak performance and maximize energy savings. Topics include the issues and choices available when selecting methods and instruments for field testing HVAC systems. Case studies will be provided. December 2 (Thursday), 8:30 AM - 4:00 PM, Edison CTAC, Irwindale register >

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