Making Buildings Work Better

To Functionally Test or Not

There have been debates for years about what terms to use for the different commissioning tasks. One of those tasks is Functional Testing. There have been several suggestions for alternative terms. Below are my thoughts on some of the terms suggested to me.


There are several different tests used during the construction process and there are many different people who are responsible for each one. Testing is non-descript term and does not define anything. If you use this term, then everyone has to ask, “What testing are you talking about”. The commissioning authority would have to go into a painful contortion of trying to describe what they were talking about without actually giving a name to the term. Or  the CxA would end up giving their own name to the testing, thus adding to the confusion that already exists regarding the commissioning process. Can you imagine the following conversation of the CxA giving the contractor a copy of the Emergency Power Functional Test?

CxA:  Here is the copy of the Emergency Power System Test

Contractor:  What are you talking about?

CxA:  This is the Emergency Power System Test.  Are you ready for testing?

Contractor:  I already finished the testing.

CxA: No, I’m talking about my testing, are you ready for my testing?

Contractor: I did my testing already, I’m done.

CxA: OK good, but are you ready for my testing?

Contractor: It’s your testing, are you ready for it yourself?

CxA: No you don’t understand, you are responsible to do my testing, I just verify that you did it.

Contractor: Like $&#@, if it’s your testing, then you are responsible for it. I’ve done mine.

CxA: No, in the commissioning specifications it says that you are responsible to do the testing and I would verify it.

Contractor: Right, I did my testing, we sent you an e-mail that we were doing the testing and you didn’t show up.  That’s your problem.

CxA: What testing are you talking about?

Contractor: We have the grounding megger tests, the generator manufacturer technician did the system start-up and load bank tests. We sent you the reports.

CxA: Right, those are your tests. I need you to do my tests while I watch.

Contractor: What are you talking about?

CxA: You know, Functional Testing, my tests.

Contractor: There’s nothing in the specs about Functional Testing.

CxA: Yes there is, look in the commissioning section.

Contractor: Show me where it says Functional Testing in the spec.

CxA: Well it doesn’t say the words “Functional Testing,” but it describes that you need to do it.

Contractor: It says I am supposed to perform the “testing” and you would verify it. I did my testing, and you never showed up.

CxA: But the spec is talking about additional testing and you have to do it.

Contractor: What is testing called?

CxA: “Testing”.

Contractor: You know what, I’ve done my “testing”. All I’m required to do is what’s in the contract documents. And the way I read it, I did the “testing” just like it said. Now if you want to do your own testing, and you want me do it for you while you watch, then let me take this “test” paper and I’ll get back to you with a price.

This is not an argument that I want to get into, and a contractor will win an argument about ambiguity every time.

Functional Testing is a testing process separate from the contractor’s other tests and it should have its own name and be clearly defined in the contract documents.

Commissioning Testing

This term has some merit in that it at least gives a name to the testing and it is good that the term is associated with commissioning.  The downfalls of this term are that it propagates the fallacy that commissioning is only functional testing. One of the biggest battles of the commissioning industry has been to convince people that commissioning is a quality control process beginning at the planning phase and continuing through the life of the building. The “testing” done just before owner acceptance is just only one of the defined tasks of the commissioning process. The other negative about this term is that it implies that the CxA is responsible for all of the testing. There are many other people besides the CxA who need to be involved in the Functional Testing. This term would be a step back for the commissioning industry.

Acceptance Testing

This term is used by USGBC to describe the Functional Testing activity. This adds confusion to the commissioning industry because this term is also used for the testing done by special inspectors such as the Fire Marshall. It also is a problem in that the term implies that the Commissioning Authority’s role is to accept the system. The CxA’s role is to document the Functional Testing and then recommend to the owner that they accept the system.

Functional Testing

The merits of this term are familiarity and it also accurately describes the testing. People are familiar with the term which has been used in the commissioning industry since ASHRAE Guideline 1 was published in 1989. ASHRAE GL 1 used the term Functional Performance Testing. ASHRAE eventually dropped this term because they did not like the implications of performance in the term and eventually began using the term “testing” because they couldn’t agree on any other term. Functional Testing is a shortened version of FPT. Some of the reasons for shortening the term to just Functional Testing is because “performance” is somewhat redundant in meaning with “functional” but it also implies that the testing will verify performance. This is not the case. The Functional Testing process verifies that the system operates according to the sequence of controls, which should be congruent with the OPR. Functional testing does not verify equipment performance such as BTUh output, heat transfer capacity, etc. The term “Functional Testing” addresses the concerns that the ASHRAE  Commissioning standards committee had and also keeps an accurate familiar industry term.

One of the arguments against the term Functional Testing, is that it is a whole building process and we are not just testing HVAC systems. The argument continues to say that the term does not apply to Building envelope testing. I disagree with this argument. Every test that I have looked at for building envelope is verifying the functionality of either a system or a system sub-component in the same way as HVAC system functional testing. All of the building envelope components have a functionality or they would not put it into the building; air movement control, moisture transfer control, temperature transfer control, sound transfer control, etc. All of the ASTM Functional Tests that I have worked with, either directly or indirectly test the functionality of one or more of the building envelope systems or subsystems. Building pressure Functional Testing tests the air barrier system as well as construction quality in general. Adhesive pull tests verify attachment of the vapor barrier which is an indirect measurement of the proper installation and effectiveness (functionality) of the vapor barrier. Thermographic imaging does not directly test any systems but with proper interpretation can give tremendous information about the functionality of the building envelope and it’s subsystems.

In short, Functional Testing is a familiar industry term that accurately describes the commissioning process activity that the commissioning team uses prior to turning the building over to the owner, and it is a more appropriate term to use than any of the other terms proposed so far.

Integrated System Testing

This is a term that has seemed to come from the data center building sector. It describes testing the systems together, introducing multiple points of change, or failure into different systems and seeing how the system responds and recovers. It is always done after the Functional Testing. Unfortunately, there is a misunderstanding among many Cx providers of what Functional Testing should entail, because IST should be the last step of the FT process. The FT process should begin with components, then move to subsystems, then to systems, and then finally to testing all of the building systems together. Testing all of the building systems together is the definition of the IST. The IST term should not replace Functional Testing, but rather it should be understood that it is the last step of FT.

In summary, my strong opinion is that the BCA should properly define Functional Testing and use this term in the Best Practices of New Construction. Doing otherwise would make this standard different from all of the other BCA documents as well as inconsistent with the rest of the commissioning industry. The only exception may be the new ASHRAE Guideline 0. I believe that if no one else goes along with ASHRAE, they will eventually recognize their mistake and begin using the term Functional Testing in future guideline additions, especially if the BCA properly defines the term and uses it in their standards.

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As a leader in the building commissioning industry, Total Building Commissioning (TBC) is a facility consulting firm that specializes in the commissioning of mechanical, electrical, controls and all other major building systems as well as LEED™ certification consulting.

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