I walked into my neighborhood home improvement store a few weeks ago and was intrigued at the choice selection that was available for low energy light bulbs. There were T-5s, T-8s, T12s, CFLs, LEDs, all with different wattages, different illumination levels. There is a market for these devices because facility operators are concerned about the cost of energy. In early February 2015 Apple Inc. announced that its new data facility, to be built in 2016, will be powered by a solar farm on the facility. While saving energy is good, commissioning, however, is an equally important pathway to achieving energy savings and reductions in greenhouse gas emissions.
Energy savings by themselves are valued more than the cost of the commissioning process, with associated reductions in greenhouse gas emissions coming at a “negative” cost. The median cost of conserved carbon is negative: -$110 per tonne for existing buildings and -$25 per tonne for new construction. This is quite phenomenal when compared with market prices for carbon trading and offsets in the +$10 to +$30 range. The non-energy benefits, however, surpass the benefits from energy-management practices. Significant first-cost savings (e.g. through right-sizing of heating and cooling equipment) routinely offset the cost of commissioning. Worker comfort is improved, indoor air quality issues are mitigated, and the competence of in-house staff is improved, among other non-energy benefits. When taken together, the net median commissioning project cost was reduced by 49%.
Smallest Common Denominator
The smallest common denominator in commissioning is that the quality each task of the project is measured, and an issue is raised when the quality is low. In a more formal sense, building systems commissioning is an owner’s quality process that measures, verifies, and documents that the Owner’s Project Requirements (OPR) are being met.
The commissioning process can only be successful if the owner’s needs are defined and well understood. This is the first order of business for the CxA on any project. The OPR should be carefully defined then used as the benchmark against which all commissioning reviews is measured. Any violation of the OPR is viewed as poor quality, which constitutes a Cx issue.
The quality of the project delivery is continually evaluated throughout its lifecycle via commissioning reviews, which occur during all phases of the project lifecycle. The issues that arise from these reviews are placed on a Cx issues log and are addressed during recurring. meetings.
Different Applications of Commissioning
Much of the information so far is related to new building commissioning but the Cx process has developed a few sub-categories within the discipline. The main four categories within commissioning are new building commissioning, retro-commissioning, re-commissioning, and ongoing commissioning.
Retro-commissioning responds to an owner’s desire to improve building performance, solve comfort and operational problems and reduce operating costs.The commissioning process as applied to existing buildings has a slightly different vocabulary; however, the concept is the same. The client’s requirements are defined into a CFR document, with which the building’s current operation is measured. If the building’s operation does not meet the CFR, it becomes an opportunity to improve the facility, or a Facility Improvement Measure (FIM). An improvement measure that is specific to conserving energy is termed an Energy Conservation Measure (ECM).
There are times when a building that has been previously commissioned has the need to be commissioned again. This need can arise due to a change in the building’s use and/or ownership, an onset of problems, complaints by occupants, and excessive energy bills are a few scenarios that can warrant the need for Re-Cx. This type of exercise can be more of a forensic exercise, since the building would likely be built already. The scope of work on such a project would resemble a hybrid between new building commissioning and RCx.
Continuous Commissioning (CCx)
Continuous commissioning, sometimes referred to as ongoing commissioning, is a systematic approach to identifying and correcting system problems and optimizing performance in existing buildings. Its primary focus is on ensuring the persistence of building systems optimization. CCx can be viewed as a continuous program of retro-commissioning, the main difference being that data analysis is continually being done via data loggers which remain in place and continually tracking consumption and performance. Trend analysis during CCx allows building operators to compare energy consumption at different systems and make load shedding decisions in real time.