Our President, Rebecca Ellis, has been writing a monthly column in Engineered Systems Magazine since 1998. Read June’s column below:

One of the easiest-to-create commissioning process deliverables is also one of the most valuable to the building owner/operator. I am talking about a Master Equipment List (MEL).

Every commissioned system is made up of individual pieces of equipment, and the commissioning professional must know what they are, where they are located, and why they are needed. One of the first things a commissioning professional should do is make a list of systems and which equipment belongs to each. “Systems” are not necessarily defined by industry standards, so each commissioning professional needs to define systems that make sense for each project. This is important for communicating with the project team and for ensuring system boundaries are clear and all overlaps are addressed through integration verification.

That systems list is the start to an MEL for the project. At the end of the project, it should be easy for the commissioning professional to submit a tabular list of all equipment with, at a minimum, the following information:

  • Equipment Number
  • Equipment Type
  • Equipment Location
  • What Does the Equipment Serve?

Additional information which would be very helpful in the future would include nameplate data such as manufacturer, model number, capacity, serial number, etc.

Without an MEL, all of the pertinent information would, theoretically, be available to the owner/operator in as-built drawings and O&M manuals. However, it will be orders-of-magnitude more convenient and useful as a single document.

Future owners/operators will use the MEL on a regular basis for:

  • Familiarizing new staff to the systems/equipment
  • Populating computerized maintenance management systems
  • Contracting out-sourced preventive maintenance services
  • Replacement equipment and/or parts procurement

Only since the beginning of 2020, I have met two owners/operators who did not have an MEL and suffered because of it.

One was a large industrial plant with a full-service maintenance agreement with a reputable firm. The facility engineer who was responsible for managing that contract had been in the plant for more than 5 years and trusted that “full-service” meant “everything.” However, the 20+ rooftop exhaust fans were not written into the service contract. Therefore, no one was taking care of them. During a retro-commissioning visit, we found that all exhaust fans, except those that were interlocked with and critical for the performance of specific process machinery, were non-functional; most of them with their belts broken.

The second owner/operator was relatively new to a healthcare facility and was trying to resolve uncomfortable conditions in some core areas. The root cause of the problem was also exhaust fans with broken belts. However, the building engineer was not even aware that those fans existed.

In these two cases, and essentially in all buildings, an MEL would have been a low cost/high benefit document for the owner. An MEL is one of the highest value deliverables a commissioning professional can offer.