ASHRAE Journal - June 2013 - 32

After building construction is complete, thorough prefunctional testing is vital. Properly starting up, operating, and
checking all of a building’s equipment helps ensure that all
components are producing the outputs mandated by the OPR
and BOD documents. This is the phase in which controls are
verified to be operating properly and the TAB results are verified to meet the project’s design criteria.
The functional performance testing follows the prefunctional
testing. In this phase, all building systems are proven to work
as an integrated whole, produce the desired outputs, respond to
system changes within the specified timeframe, and operate in
a stable manner. Next, the systems manual is prepared, proper owner training is completed and documented, and the final
commissioning report is prepared and presented to the owner.
The final step of a successful project is a thorough post-occupancy measurement and verification program, which verifies that the temperature, humidity, lighting, sound, vibration,
and energy-use levels specified in the OPR document have
been achieved.

the owner-developed OPR document to verify the document exists. In contrast, the technical commissioning process requires
the CxA to actively assist the owner and design team in developing the OPR document, ensure that all key requirements have
been addressed, and suggest practical process improvements.
Here’s another difference: Under process commissioning,
the CxA reviews the BOD document against the project design documents to ensure OPR conformance. But under technical commissioning, the CxA reviews the design documents
more thoroughly, conducting detailed reviews to ensure conformance with both OPR and known best practices.
Also, while technical commissioning parallels ASHRAE
Guideline 0-2005 in many areas, it differs by not allowing
sampling for design review. Under technical commissioning,
the CxA pays close attention to system setup and testing values, carefully checking and testing such design elements as
outside air quantity, systems’ diversity, design velocities, pressure drops, and damper/valve types and locations.

Process and Technical Commissioning

The differences between the two forms of commissioning
become more evident in the construction phase, in which the
technical commissioning process employs more robust testing
and verification than process commissioning.
Inspections. The process commissioning authority reviews
the inspection forms that have been prepared and completed
by installing contractors, and verifies that all quality control
(QC) forms have been properly completed. Process commissioning calls for the CxA to observe the controls contractor
during system startup, and review the contractor’s reports to
verify completion. The CxA also obtains “samples” from the
TAB report to verify compliance.
In contrast, the technical commissioning authority actually
prepares the necessary QC forms and performs on-site verifications of QC inspections and contractors’ tests to ensure
quality construction. The technical commissioning authority
also performs a point-to-point test of all system controls and
verifies the accuracy and proper calibration of all system sensors and any computer-generated graphics. Sampling is not
allowed. Finally, under technical commissioning the CxA verifies the TAB report to ensure accuracy and lists all construction, operational, and functional deficiencies in an issue log.
Functional performance tests. Process commissioning
calls for the commissioning authority to prepare all functional performance tests (FPTs), but the tests are performed
and documented by the installing contractors. The CxA uses
an issue log to record any issues that are uncovered during
testing, and documents those issues in the final report. Note
that although there may be CxA records issues that do not
conform to the OPR document, he or she may not necessarily work to resolve them. The responsibility for resolution
usually rests with the design and construction team—a delegation that too often results in a “circle of blame,” in which
each party points to the next party and problems may never
be fully resolved.

The USGBC and its LEED certification guidelines have greatly
improved the quality of today’s design and construction processes. However, many new buildings still do not meet their owners’
expectations—whether or not they are LEED certified. Published
literature indicates that between 28% and 35% of LEED-certified
buildings do not meet their energy-use projections.2
While poor building performance can often be traced back to
the design and construction phases, there may also be another
culprit: the type of commissioning employed on a given project.
As noted, two forms of commissioning have evolved over
time: process commissioning and technical commissioning.
Process commissioning manages project quality by observing and reviewing the inspection and testing processes that are
followed by the project’s designers, engineers, and contractors. In this form of commissioning, engineers and contractors
serve as the project’s technical experts and provide the testing
expertise for building operations and testing. Under process
commissioning, the commissioning authority (called the CxA
by the USGBC) provides the outline of the commissioning
process, which is then implemented by engineers and/or contractors—who are required to provide only a sampling of test
results from either work in-process or completed.
Technical commissioning is based primarily on hands-on
inspections and functional testing and verification of building systems performance. This form of commissioning does
not rely on observing or reviewing inspection and testing processes performed by others. The technical commissioning approach ensures that the CxA is the final expert that actually
performs or observes proper testing on all building systems.
The only sampling permitted under technical commissioning is sufficient testing of the testing, adjusting and balancing
(TAB) report to verify that the TAB report is correct.
While both commissioning approaches begin with an OPR
document, process commissioning calls for the CxA to review
32

ASHRAE Journal

Process vs. Technical Commissioning

ashrae.org

June 2013

ASHRAE Journal - June 2013

Table of Contents for the Digital Edition of ASHRAE Journal - June 2013