Understanding Commissioning
I recently received an RFP for building commissioning services that included the following statements:
“Everyone intuitively knows what commissioning is.”
“Commissioning is what architects and engineers would do if they had more funding during the construction administration phase of the project.”
I disagree on both counts. First, the authors of the RFP appear to have a very different understanding of building commissioning than the organizations developing the standards, including ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers), the Building Commissioning Association and California’s Commissioning Collaborative. And second, having been a project manager of major MEP (mechanical, electrical, plumbing) design projects in the 1980s when construction administration fees were robust, I can attest that even notable firms such as Syska and Hennessy and Glumac did not provide the thorough verification of systems then that is required under a rigorous commissioning protocol now. So what makes an engineering service that has been around for decades so hard to understand and evaluate?
Comparing “Apples to Apples”
One difficulty is that the level and detail of commissioning is not uniform from one provider to the next. Rigorous commissioning takes more time, thereby increasing the cost of commissioning services. In order to compare proposals, building owners must determine whether the cost differences between providers are due to increased efficiency or reduced rigor. Owners will be more likely to get proposals that meet their needs if they stipulate the expected level or rigor up front, but they may not know what to look for.
One Building, Two Steps, and Three Levels of Rigor
As an example, let’s walk through two of the key steps in the commissioning process and outline the range of service quality (poor, medium and excellent) that you may receive if you hire a commissioning agent without specifying the expected level of rigor in the RFP. I’ve also roughly estimated the approximate time and cost associated with the various approaches, assuming a 50,000 square foot building with boiler, cooling tower and heat pumps for HVAC.
1. Design Review (Pre-Construction)
Design review at around 100% Design Development is required under the LEED Enhanced commissioning credit. LEED has minimal requirements for what a CxA (Commissioning Authority) should look for in the design review; the options below apply to any design review. The CxA should be the owner’s advocate during the design review process necessitating that the CxA have a detailed understanding of the design principles underlying the systems they are reviewing.
Poor: Drawings are spot checked for errors, the CxA looks for their pet peeves, a memo is produced documenting any findings. 0-20 issues may be identified, which may give the owner the false impression that all is well. (Time spent 4 hours, cost $520)
Medium: A detailed coordination check between mechanical and electrical drawings is provided, drawings are spot checked for constructability and ability to be commissioned and maintained. Findings are documented in a memo or matrix and a meeting is held to discuss. A minimal back-check is provided. Such reviews often unearth from 5- 30 issues. (Time spent 12 hrs, cost $1,560)
Excellent: Starts with the verification that the selected system approaches are optimal for meeting the Owner’s Project Requirements. Thorough review of plans and specifications looks at sizing, energy efficiency, optimization (for instance - can duct runs be shorter to reduce fan load), code compliance – particularly compliance with the minimum requirements of ASHRAE 90.1-2010, coordination, constructability and maintainability. The findings are documented, the design team responds and the status of each issue is tracked from identification to closure in a commissioning review matrix. The team meets, using the matrix as a guide for discussion and the CxA provides a thorough back check of plans to ensure they include all agreed upon changes. Over 100 significant issues are typically unearthed through this level of design review. Identifying and addressing problems during design significantly reduces the cost of resolution. (Time spent 24 hours, cost $3,120)
Example: A major university selected a commissioning provider for a new project based on price. The selected Commissioning Authority provided 3 design review comments. The MEP engineer, having experienced a thorough design review, advocated for a second more rigorous design review. Our firm was selected to provide this service and we provided over 120 useful design review comments.
The additional cost of an “Excellent” review will likely be paid for in less than 12 months due to reduced construction change orders, more efficient operations and first cost savings due to a tighter design.
2. Functional Performance Testing (Post-Construction)
Functional Performance Testing (FPT) occurs after the CxA has verified that the specified equipment is installed correctly, energized and correctly balanced. I have had contractors tell me when we are testing a piece of equipment “so and so doesn’t make me do this when they commission it.” And, I’ve seen other commissioning provider’s FPT test documents that consist of a check box indicating “this system has been functionally tested and operates as documented in the plans and specifications.”
Many commissioning providers do not even own calibrated test instruments while other firms routinely provide independent testing and calibration validation as part of the commissioning service. Knowing what you are getting in this phase of the work is largely the difference between wasting your money on a service that is unlikely to deliver results versus investing in the assurance that you are getting what you pay for.
Poor: The CxA verifies on/off operation and spot checks temperature tracking of HVAC equipment. The central Building Management System (BMS) central computer is used for testing without validation that the actions shown on the computer are in fact actually occurring in the system. Sign-off on system at end of test. Few commissioning issues are identified; minimal follow-up is provided to get issues addressed. (24 hours, $3,120)
Medium: CxA develops FPT documents that outline the essence of the mechanical sequences of operation for mechanical system. These documents are used to test equipment and spot validate performance of equipment against the BMS system. Issues are documented in an issue log and closed as the contractor indicates completion. Follow-up to ensure issues are resolved is minimal. (50 Hours, $6,500)
Excellent: The CxA has already worked with the engineer and controls contractor to establish a fully detailed sequence of operation for the building during the design and submittal phases (this important step is rarely required in commissioning RFPs, but is an essential step in the commissioning process). The CxA uses the final sequence of operation to write detailed FPT documents that can be used to validate each required operation and function in the system. The CxA uses NIST (National Institute of Standards and Technology) certified test instruments to calibrate BMS sensors and relies on the central BMS’s reporting and display only after the accuracy of these components has been field verified. Every step in the sequence of operation for central equipment is tested along with a statistically valid random sample of terminal devices and controls. Additional opportunities to improve control are identified during testing and provided to the Owner and design team as an “Owner Issue” which, where significant, may require the owner to authorize additional services for the design team and CxA and a change order for the contractor. Findings are documented in a field report and a commissioning issues log. The CxA works actively with the contractors, owner and design team to get commissioning issues addressed and field verifies their completion. This approach typically identifies many otherwise hidden issues and ensures they are resolved before the contractors are off the job. (90 Hours, $11,700)
Getting it Right
Relying on “intuitive” understanding of a service that is not uniform in the marketplace often results in wasted money and building systems that don’t perform as expected “even with commissioning.” You, as a building owner or consultant, can benefit from developing an understanding of the levels of commissioning available and the level of rigor, skills, knowledge, and test instruments that various providers bring to their projects.
Commissioning costs are often estimated as $$/square foot or % of construction cost with no definition of the expected level of rigor or understanding of how the complexity and/or size of the project will affect commissioning costs. Commissioning done right costs more than the $0.50 - $1.00/square foot rules of thumb often used for budgeting purposes. Because of the highly variable level of services provided from one firm to another, defining the expected level of rigor in a commissioning RFP is the only way to ensure you really get the quality of services you want and need.
