QSE Logo

LetsTalk2015@QSEng.com
612.308.4716

What is a Test?

Last month’s Getting it Right column (September, 2005) acknowledged that there are various levels of testing rigor currently provided by commissioning professionals. When developing their commissioning procurement scope of work facility owners need to make an effort to specify the level of testing rigor and documentation required. Simply requiring the commissioning professional to “test” systems is risky, because that term is not universally defined or understood.

There is a continuous spectrum of testing preparation, execution, and documentation rigor in practice today. The following table captures a range of approaches taken by commissioning providers. It is safe to say that each commissioning provider’s approach is unique and falls somewhere within the bounds of this table.

Level of Rigor

Preparation

Execution

Documentation

High

Customized detailed step-by-step test procedures with pass/fail acceptance criteria for each step

Cx Provider directs contractor through all steps, from start to finish in a single testing session.

Pass/fail of each step documented on test procedure form and separate summary test report and action list

Medium High

Generic test procedures with generic acceptance criteria customized for the systems to be commissioned

Cx Provider decides in the field exactly how to execute the generic test procedures. Contractor performs test under Cx Provider direction.

Pass/fail of each acceptance criteria documented on test procedure form and recommendation for acceptance or rejection.

Medium

Generic test procedures customized for the systems to be commissioned

Cx Provider decides in the field exactly how to execute the generic test procedures. Contractor performs test under Cx Provider direction.

Test report documenting problems found and recommending acceptance or rejection.

Medium Low

Generic test procedures selected based on review of design documents and system shop drawings

Cx Provider uses generic test procedures to guide the testing of various system functions, deciding on applicability to the project’s systems once in the field.

Test report documenting problems found and recommending acceptance or rejection

Low

Familiarization with design documents

Cx Provider observes system operation and decides what sequences or modes to check out once in the field

Test report recommending acceptance or rejection

My definition of a “generic” test procedure is one that is intended to be “one size fits all” for a particular type of system, e.g., constant volume air handling unit, variable volume air handling unit, heating hot water system, variable volume reheat terminal unit, laboratory environmental control system, etc. It provides a list of typical control sequences that need to be verified as operating properly without providing details regarding how to do that.

Because each new building system is designed differently, the specifics of how the sequences operate and, therefore, the details of how to test those sequences need to be customized in order to more rigorously test the unique new systems. In the above table, the difference between Medium Low and Medium is the customization of the generic test procedures. This customization is simply removing the generic sequences of operation that do not apply to the specific systems being tested and adding sequences that may not have been addressed in the standard generic procedures.

The Medium High and High levels of rigor are where the test procedures are customized to include acceptance criteria in the written test protocol. Medium High uses the generic test procedures with equally generic acceptance criteria. The High rigor test procedures are fully customized and documented ahead of time to step-by-step test each mode of operation exactly as defined by the design engineers. The design engineers’ specified functional performance is used as the pass/fail acceptance criteria.

The best way to judge a commissioning provider’s approach to testing is to request example test procedures and reports and to request a narrative description of their test preparation, execution, and documentation processes. Next month we’ll address the advantages and disadvantages of the various levels of rigor.

 

COMMISSIONING: GETTING IT RIGHT

Engineered Systems, October, 2005

by
Rebecca Ellis, PE, LEED AP, CCP, CxA
President
Questions & Solutions Engineering
1079 Falls Curve
Chaska, MN  55318
rteesmag@QSEng.com