Tales from the Script: What Is “Ready” in Commissioning?

By April 29, 2021Conduit

Greenfield data centers are built the same way most other facilities are built: the building schedule is driven by constructability. From design through turnover, the primary and often the only driver is efficient, linear construction. While this makes perfect sense for most facilities, this traditional process leads to copious issues involving commissioning, schedule, and budget in a data center. The data center MEP equipment’s criticality creates a need for commissioning that far exceeds the typical construction process. The contractors, vendors, commissioning agent, and owner are often left wondering what is “ready” in the commissioning process.

Thorough testing and commissioning affect a data center’s reliability and operation as much if not more than any other construction aspect of the facility. This question’s definition and the possible answers can profoundly impact data center design, construction, and schedule. The general understanding of “ready to commission” by most in the industry means when one power source is turned on to a piece of equipment. The true definition of ready occurs when equipment has been installed and tested, has electrical power from all sources, has control power, is networked, and can be tested as a complete system.

One example is a chiller plant. A chiller is not ready to commission as soon as the chiller is installed; it must have piping complete, water flushing and filling, electrical power, controls installed and networked, vendor startup, and test and balance complete. If any of these pieces are missing, although some parts of commissioning can be done, the chiller system as a whole will have to be revisited at a later date. Touching equipment more than once results in a circular commissioning process, not linear. This non-linear, inefficient commissioning process eats up the commissioning budget, time in the schedule, can lead to missed issues, and ultimately frustrates the owner.

Another example is a critical power reserve (alternate) bus, common in data center electrical power distribution. The contractor installs static transfer switches (STS), connects the primary power source, and calls for commissioning to start. But an STS has two sources of power – the second one is the reserve bus. Due to the multiple points that a reserve bus touches, this bus often isn’t installed until much later in the construction process. Without the reserve bus in place, the STS can’t be commissioned.

In a construction driven process, the negative commissioning consequences include:

  • Pushing tasks further into the schedule effectively compressing the commissioning schedule
  • Skipping tasks towards the end to make the turnover date
  • Focusing on the component operation and not system operation
  • Never observing steady-state operation, particularly on the mechanical side, to work out bugs
  • A sliding project end date
  • An end product that does not meet the owner’s expectations

“The construction team had a tough time adhering to a schedule that made sense from a commissioning perspective. We needed to have the commissioning agent, HP&D, more involved in the planning phase so the construction team can produce the building in a more efficient manner.” Data Center Owner


The solution to the readiness issue is to consider commissioning and MEP systems in the same way you consider construction. The data center owner should have a dialogue with the general contractor, design engineer (MEP) and commissioning firm to determine commissionability based construction scheduling. Questions to consider:

  • How can you construct and install so that the data center is ready for commissioning earlier in the schedule?
  • Can you build in more time for startup and commissioning?
  • Can you design the large mechanical and electrical systems to be broken down into smaller pieces that can be installed and commissioned in segments? An added benefit to this type of design consideration is an increase in isolated systems, which lead to greater reliability, ease of operation, and long-term maintainability. As always, risk versus reward should be considered along with costs.

This type of deliberation is much more prevalent in live building retro- or re-commissioning. The stakes are much higher with live load, so every impact and impediment is taken into account with regards to commissioning. In this case, the decisions are infrastructure-driven, not construction-driven, and the commissioning firm is actively involved in the decision-making process from the beginning.

Today, data center construction is well defined in terms of cost, schedule, and expectations. For commissioning, it is possible to achieve the same level of predictability in cost, schedule and outcome if owners/operators will work with their design engineer, general contractor, and commissioning firm to come up with schematic design and construction solutions that meet everyone’s needs and deliver data center projects on time and on budget.