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  • Alex Mathers

What Most People Don't Understand about Integrated System Testing

Integrated System Testing stands as an indispensable component in the commissioning process for buildings and facilities. By rigorously testing and validating the interoperability, performance, and compliance of integrated systems, IST ensures that commissioned facilities not only meet but exceed the expectations of owners, occupants, and regulatory authorities. As the construction and facility management landscape evolves, IST remains a cornerstone in achieving excellence in building and facility commissioning.


Commissioning is the proactive systematic process of ensuring that a building's systems and components are designed, installed, tested, operated, and maintained according to the operational requirements of the owner. The process of commissioning includes tasks at various stages of the construction process including design pre-construction, construction and post-occupancy.


The most involved task of commissioning is functional testing, aka functional-performance testing (FPT).  Functional-performance tests are system and equipment specific evaluations.  They are in isolation of outside influences, verifying the stated performance of a system and comparing the results to design assumptions. FPT involves testing each system independently to verify that it performs according to the design specifications and functional requirements. This includes HVAC systems, lighting controls, electrical systems, plumbing, fire protection, and other building systems.


Integrated System Testing (IST) occurs after functional testing.  Once systems and equipment are verified independently, it is now time to see how they work together. This is where the rubber meets the road because instead of systems from one engineer and one trade having to work together (i.e. mechanical AHU and VAVs), now we bring in the variable of electrical, fire alarm, process and system integrations. It is one thing for an engineer to design and sequence a system solely in their purview, or for a contractor to only have to coordinate with themselves and their direct subcontractors. Now, with integrated systems, we as CxAs get to see how well the teams coordinated across trades.



Did mechanical integrate correctly with fire alarm? Did controls remember to wire their transformers to e-power? Did electrical get the generator phase rotation correct? Did process include UPS power in their scope? Are redundant systems programmed correctly?    


Integrated System Testing involves testing all of the systems and components of a building to verify that they function cohesively and meet the intended performance criteria. This includes evaluating the interactions between HVAC systems, plumbing, process, lighting, security, fire protection, and other building systems.


While there are many different types of ISTs, the most common is a “Blackout Test”, also call a loss of power response test, pull-the-plug test, or a Level 5 test in data centers. The intent of a blackout test is to verify business continuity during a power failure.  That is, can the facility continue to perform safely, with no interruption in service, in the event of an unplanned utility power outage?


Misunderstanding #1: Since blackouts are an unplanned event, the IST test does not require planning


“If You Fail to Plan, You Are Planning to Fail.” An IST is an all hands on deck affair.  It typically takes weeks to months to plan a successful IST.  Everyone needs to be involved from the Owner to the tenants, to the subcontractors to the EORs. A detailed MOP (Method of Procedure) needs to be in-place and approved. Everyone needs to understand what to expect, and have a plan, for what if things fail. Server room CRAC units don’t come back online? Better quickly get some cooling or restore power and hope the issue clears. Lab exhaust fans trip off and fume hoods are alarming? Better get someone on the roof ASAP (or better yet, have someone there already).The CxA should use their experience to plan the event for the owner.

 Misunderstanding #2: The IST is an electrical test

While the blackout test does functionally test the Emergency Power Supply System (EPSS) including generator, ATS, switchgear, uninterruptible power supplies (UPS), and EPSS distribution and e-power receptacles, it is not solely, or even mainly, an electrical test. 


The IST does include the confirmation of the NFPA 110 requirements including 10 second power restoration timing of Type 10 systems, generator loading, transient response, and acceptable power quality. The emergency lighting power inverter, exit signs, and egress lighting illumination is also verified during an IST.


However, what is also important to verify during an IST is how the HVAC, plumbing, process, and fire alarm systems react to abruptly losing power for 10 seconds and then suddenly regaining power.


I can tell you from experience, most of the issues found are mechanical related. Spring return dampers close, sometime tripping off AHUs as they come back online, BMS field controllers lose memory, sometimes wiping out all stored flow coefficients, equipment such as humidifiers, fan coils and exhaust fans don’t come back online (or were never put on standby even though drawings were clear).


While the power is out for only 10 seconds, much of the HVAC equipment takes 30 seconds to sometimes 5 minutes to come back online.  If this restart is not sequenced correctly, trip outs, resets and manual overrides are required.


Sometimes, issues are not installation issues, but design issues. I have seen a few lab buildings with lab exhaust on e-power, but supply AHUs are not to save the cost of a larger generator. The thinking is that if a central plant is not on generator, and CHW or HHW is not available, then why add the AHU? Well, what happens is when the utility power is off and exhaust fans are still running at their set speed, with no supply you are creating a very negative space.  So negative in fact, I have seen door opening forces as high as 60 lbs.  So congrats, you saved some money, but now you have trapped everyone inside.



Misunderstanding #3: Once everything is verified on e-power, the IST is complete


While transitioning to generator is important, equally as important is the return to normal power.  Oddly, I have seen more issues once normal power is restored than going on to generator. The reason may be because of the return sequence.  When utility power comes back online, everything on normal power instantly has power again. The equipment that was not on emergency or standby now has power after being off for 2-3 hours. However, everything on the emergency or standby is still on generator. 

Once the ATS sees normal power, it starts a (typically) 5-10 minute timer to verify the normal power restoration will be permanent and to verify the transition is in-phase. Once that timer is done, only then does the ATS transfers emergency or standby from generator to normal. While everything else has been on for 5 or 10 minutes (AHUs, fans, BMS), now emergency or standby sees another power blip. This one is quick, 15-150 milliseconds, but that is just enough time for the power gremlins to come out a second time.  VFDs sometimes lose communications, inrush current trips breakers, UPSs take a second hit.


Misunderstanding #4: Ok, now everything is done


Nope.  Now you have a 15-30 minute generator cool down. While you are waiting, it is a good time to compare notes. There is a lot going on during an IST - it is impossible for one person to capture everything. Did someone check the generator annunciator panel?  Did you check all of the e-power receptacles (even the ones in the ceiling utility panels and in the elevator pit)? Did the elevator recall or shutdown work as intended?  Did all the alarms clear? Did remote notifications work? Were smoke dampers powered?


Misunderstanding #5: Blackout ISTs are only for buildings with emergency or standby generators


Just because a building does not have a EPSS doesn’t mean it doesn’t need an IST.  One way to determine if a system qualifies for IST is if any two systems are designed or installed by two or more contractors or engineers.  Any building or facility is susceptible to a utility power outage and failure of equipment during an outage (i.e. lighting inverters) or during restart can affect health and life safety and business continuity. 

The number and duration of power outages in the U.S. continue to rise, driven primarily by weather-related incidents. The average outage duration in the U.S. is 120 minutes and climbing annually. The purpose of an IST is to test the integration of two or more interconnected systems, in the case of a blackout test, in the event of a power outage. Systems requiring integrated systems testing include electrical, HVAC, plumbing, process, fire alarm, fire protection and may also include smoke control systems, stairwell pressurization systems, magnetic door holds among others.


ISTs are one of the last tests for construction phase commissioning.  It is the culmination of all the work that led up to that point. A successful IST (even if it takes two or three tries) is a great team builder and something that every participant should be proud of.

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