Importance of Commissioning Buildings with HVAC Controlled by DDC or BAS

The best practice is plain and simple:  Commissioning should start before design, as outlined by ASHRAE and other industries.  This is easy to say but takes discipline to do.  In this blog, we are going to discuss why you need to perform commissioning at the startup phase of any HVAC equipment that is controlled by a BAS or DDC system.

What exactly is commissioning?

Fun fact:  The term commissioning comes from the navy and its operations for preparing ships. In an engineering context commissioning now means the process of ensuring that all systems in a new building meet the owner’s specifications. At DMA Engineering, this process involves a collaborative approach, uniting designers, contractors, and stakeholders to document, test, and verify systems like HVAC, electrical, and plumbing. Our method guarantees optimal performance, safety, and efficiency extending 12 months post-occupancy,  distinguishing us at DMA Engineering as a trusted commissioning partner.

Why does a building that has a DDC or BAS need to be commissioned?

Because misunderstandings and omissions are much more common than we would like. Commissioning is especially important for buildings with Direct Digital Control (DDC) and Building Automation System (BAS), because of their complex systems that automatically control a building’s various systems, such as HVAC, lighting, and power.

Is it risky to skip commissioning at the beginning of a project?

Yes, it’s risky to skip commissioning at the start-up phase of any HVAC project. Here is an example of how things can easily go wrong: The first engineer writes the sequence of operations but leaves out details, then the controls engineer fills in their interpretation rather than asking the first engineer. This controls engineer inherits the confusion, will not understand the sequence of operations and may simply use a sequence they used on a similar building. This is a huge problem, because the current building just inherited the same issues as the former building.

If the control system that was originally specified is not actually being used, the design engineer may not be fully aware of how the installed system operates. While a graphical user interface (GUI) can demonstrate a lot, looking at the actual programming shows what the programmed sequence of operations is doing. Having trend data to review against the GUI, the programmed sequence of operations is a way to graph the system performance and verify the system is working correctly.

Why is the early timing so important?

Many builders try to get through the warranty phase and then let the buildings maintenance personnel work through the issues, instead of proactively performing the commissioning.  In today’s world building engineers are overworked and understaffed while managing more complex systems and a tighter operating budget.  Costly problems can occur when it takes years for the building staff to fully understand that system was not set up correctly in the beginning, and then they need to devise work arounds or abandon the operation of equipment all together and go with alternate solutions.

Buildings that are not commissioned often face numerous challenges and operational inefficiencies. Without a thorough commissioning process, there can be significant discrepancies between the design intent and the actual performance of the building systems. Issues such as incorrect sequence of operations, misunderstood control systems, and unresolved deficiencies can lead to persistent problems.

Moreover, the absence of commissioning can result in higher energy consumption, frequent equipment failures, and uncomfortable indoor environments. These issues not only frustrate the building occupants but also result in increased maintenance costs and reduced lifespan of the building systems.

How can a third-party commissioning help me?

For smaller projects using a rule of thumb under 10,000 square feet (even though we engineers don’t like rules of thumb!), there should be no problem with your design engineer commissioning your project, provided you trust the design engineer.  For example, we at DMA Engineering commission our own luxury residential projects and small commercial buildings up to 10,000 square feet.  For larger commercial and residential projects, DMA can complete a third-party commissioning (or re-commissioning) to maintain objectivity and provide credibility for all stakeholders in these 10,000+ square feet projects.

Whether your commissioning company is DMA Engineering or another entity, the commissioning engineers must be empowered and contracted to deliver a building that works per the design documents. They must drive deficiencies to resolution, especially in complex HVAC systems where a deficiency is frequently just a symptom of a larger problem.

How can I do it right?

Commissioning ensures that the building operates as intended, delivering optimal performance and value to the client.  Successful commissioning will:

• Get the client the building they paid for.
• Deliver a building that meets the design documents.
• Set the building on the correct path to operate correctly for years to come.
• Greatly reduce the number of service trucks at the project after the first year. While we cannot guarantee there will be no service trucks, we can say that the maintenance of the building will be easier and less costly in future years.
• Save more energy than in a non-commissioned building. Fact: All buildings will soon be required to meet a certain Energy Use Index, (EUI). If you are behind the starting line on this EUI requirement because your building is operating inefficiently, you will be required to pay for an energy audit, then a retro-commissioning, meaning you will be essentially paying twice for commissioning.

Can you give me an example?

Here is a simple success story of a DMA Engineering commissioning project.  DMA commissioned a project, in which it was reported that some control valves were not closing correctly, and the spaces were overheating. After troubleshooting with the contractor, we found that valves were not the issue at all: 1) the valves were wired and adjusted correctly, and 2) the control head was installed correctly. Knowing that the valves were not the issue, we dug deeper and found that the entire floor supply and return water were reversed, revealing that the valve was trying to close against the water flow and therefore lifting.

We are very pleased that the commissioning project permitted us to go beyond the initial inspection of “valves are OK” so that we could drive toward the real resolution. We helped the building owner avoid the lengthy and frustrating process of writing up a deficiency, negotiating with the contractor, and working through the finger-pointing.  This commissioning efficiently and accurately identified the accountability for the problem and pointed to a clear solution. This is what the building owner wants:  a working building, not a grueling process.