CxE, defined
During the design phase, the CxE is responsible for one or more design reviews based on the commissioning scope of work and/or the LEED® additional commissioning credit compliance. The CxE review is to provide a third-party overview of the basis of design and to comment on the accessibility and commissionability of the systems being commissioned. It is not the CxE's responsibility to displace the engineer-of-record's responsibility to ensure the system is going to perform as expected, but frequently, the CxE is being put into a position that can challenge the engineer's design due to the CxE review.Some design engineers may dispute the CxE's design review comments, even when an owner hires this specialist to provide the services requested, as more and more HVAC designs are leaving a lot to be desired from the point of completeness, efficient performance, and the ability to achieve the basis of design.
This enhanced design review request is reinforced by noting that there is now a new, booming business called troubleshooting/post-construction commissioning of installations that are relatively new (completed within two years) but which have not met the owner's building program expectations. It is a business being driven by unhappy building owners.
This expanded CxE role is also a result of being more proactive in the construction phase as compared to the time being spent by design engineers in this phase of the work. This is an unfortunate dilemma for the designer who probably doesn't have much consulting engineering fee remaining once the construction gets under way. The CxE is frequently driving this extra effort so that "business as usual" doesn't continue as it pertains to contractors' saying systems are ready when the equipment really isn't ready.
Some CxE firms are now specifying detailed project scheduling milestones in the design phase as part of their commissioning specifications. In the construction phase, the CxE will then own the contractor requirement to fill in the due dates as part of the overall project schedule. While this may be perceived as an extra effort on the CxE's part, the process has shown positive results as it contributes to the end, while avoiding unnecessary re-testing of building systems that didn't pass the various FPT demonstrations.
CXE and the TAB process
Another owner request to expand the CxE role involves taking on the third-party TAB firm. For me, personally, the addition of a third-party TAB firm, rather than the TAB contractor working for the HVAC contractor, is long overdue. With the CxE facilitating the TAB process beginning in the design phase, a much stronger TAB specification can be written along with TAB reviews that parallel the CxE design review.Enhancing the TAB process, such as requiring the production of system flow diagrams (a.k.a. TAB plans) in the shop drawing submittal phase that document pertinent performance data (flow, pressure drop, and velocity), can ensure the air and water balancing will be done according to TAB industry standards.
Not a panacea
Whether it is building-owner initiated or prompted by the CxE, the additional services and extra effort on the part of the CxE is not a cure-all for the issues, concerns, obstacles, and owner perception. Design engineers need to recognize there is a problem and make a course adjustment as it pertains to client confidence. For the builder, a similar perception exists in the construction phase when the owner not completely satisfied with the deliverables at the time of certificate of occupancy.All of this may be more then just the traditional commissioning services and the extra effort certainly can be perceived as a culture change for many in the building industry but, until building program results improve, commissioning services will apparently continue to grow despite not being a magic bullet for all design and construction problems.
