Although the use of commissioning as a management tool is becoming more widespread, less than 5% of the new and existing buildings in the United States have been commissioned. This fact points to an ongoing need in the next century for recommissioning. Recommissioning, or retrocommissioning as it is sometimes called, is typically performed on older structures that either haven’t been designed or operated properly, or that are undergoing a major renovation due to age or change of purpose.

Like commissioning, recommissioning involves performance and diagnostic testing of most or all major building systems including hvac, building automation, lighting, life safety, and transportation. Mechanical systems operation and controls are most examined, likely because they create the biggest problems for owners. The results are documented, along with recommendations for improving performance.

Why Do It?

Recommissioning is a value-enhancing program for building owners and facility managers. Contrary to the common fear that it is too costly, recommissioning is actually one of the most cost-effective management decisions an owner can make.

Indeed, most of the advantages of recommissioning include economic benefits. A thorough investigation and analysis of the hvac system, for instance, can lead to improvements that will reduce operating costs. A system upgrade may well enhance occupant comfort and productivity, in turn increasing employee and/or tenant retention. Improved energy utilization can translate into extensive savings on utility bills.

Like commissioning, the goal of recommissioning is to ensure that all the power-using and power-conserving systems in a building work together. This is done by uncovering and correcting problems, defects, and deficiencies in existing building systems.

The Root of the Problem

These problems and defects may have been part of a system from startup, or they may have developed over years of use and/or abuse. For example, the widespread practice of oversizing or other poor design concepts can be the cause of flaws in the ventilation system. Other deficiencies may arise during system installation and startup, such as not establishing building pressure control for all operating conditions.

A lack of continuity between the designer and the installing contractor may mean that a building system does not operate as intended from the start. If the contractor sets up a procedure which does not meet the design criteria, and no one has the responsibility to verify performance intent, the resulting operational sequence would be incongruous with the designer’s (and most likely the owner’s) vision.

Commissioning agents occasionally find items that were specified but never installed. A recent project uncovered a request from the owner for an outdoor air tracking system to fulfill ASHRAE Standard 62-1989 (involving indoor air quality). The system had not been installed. Until a commissioning agent was retained, the owner had no idea that his “IAQ insurance” was missing from the building.

Facilities that were designed and constructed under a design-build (D-B) contract may also have more performance problems than those delivered under the traditional design-bid-build method. In the early days of D-B, these projects often lacked a definitive understanding of design and performance criteria between the owner and the contractor. Too many times the general contractor selects the D-B mechanical contractor based on low bid, while ignoring sizing and other design and performance issues out of ignorance or greed. This occurs particularly on projects that either have no documented design/performance criteria or have documentation that is written so poorly that it is ripe for liberal interpretation by the mechanical contractor.

Another possibility is that the design proposed by a D-B mechanical contractor emphasizes the strengths of that contractor. If the contractor is primarily a sheet metal contractor, the system might have as much sheet metal as possible, coupled with package systems that reduce the necessity to include other trades, such as pipefitting. Such an approach may or may not be the best design solution for the owner.

Elsewhere, intentionally or unintentionally, service organizations sometimes miss warranty issues. The warranty on a controller, for example, may be “jerry-rigged” to work to avoid warranty expense and never repaired. This is exactly the type of problem a commissioning agent is trained to find.

Growing Old

Normal wear and tear naturally cause the degradation of systems and equipment. Often, a system will continue to function, but at a greatly reduced level of efficiency.

Complaints from building occupants and trouble call records can signal a need for recommissioning. Ventilation systems are consistently reported as one of the leading sources of complaints. Building owners attempting to do the right thing – control energy costs, for example – may be guilty of creating their own nightmares. The way a facility’s hvac system operates directly impacts the well-being of occupants. Aggressive energy management practices such as reducing system operating schedules or curtailing outside air, may put a building at risk for IAQ problems.

Changes in operating procedures by maintenance staff who lack system training can intensify building operations problems. Outdoor air dampers may be shut down during summer months, for example. A boiler or chiller may be shut off in response to a complaint about the building temperature. By negating the automatic control response, this “bandaid” will only result in more severe disorders.

Yet another reason to consider recommissioning is when the original function or purpose of a building changes. Building systems may perform as originally intended, yet not meet the standards and/or the intent of the new owners.

Whether current problems were inherent or have developed over time, the goal should be to see that the systems perform at optimum conditions to meet the needs of the current occupants and the actual performance requirements of the owners.

Timing and Personnel

Building owners and facility managers considering recommissioning must also regard the timing of the process. Optimum opportunities for this procedure include:

  • Prior to a major renovation or remodeling;
  • When a change in ownership or tenants occurs;
  • When complaints relating to comfort increase noticeably; or,
  • Worst case scenario — when a system fails.

Once an owner has made the decision to recommission a facility, who is the best person for the job? Because mechanical systems are the most frequently tested building component, professionals trained in mechanical engineering will perform this function best. At the least, the person conducting the recommissioning service must be a registered professional engineer. In-depth experience (at least 10 yrs) as a designer of MEP and FP systems, as well as field construction and construction management experience, is preferable. Skills like problem solving, value engineering, and cost control should also be second nature.

Step by Step

Starting the recommissioning procedure generally includes the following activities:

  • Converse with the owner/manager;
  • Identify current problems;
  • Study the building’s history of problems;
  • Review documentation;
  • Examine operating cost records; and
  • Develop a project plan.
If the problem can be isolated to a single component, that component is repaired and the situation re-evaluated at a set date. If, however, the problem involves multiple layers, the defects must be systematically identified. This phase includes:

  • Executing a systems study;
  • Considering original design intent;
  • Comparing current operation to design intent;
  • Studying the original application;
  • Studying any alterations to the system;
  • Identifying any relevant maintenance issues; and
  • Determining a strategic approach to resolution.

At that point, the recommissioning agent has two options: restore the system to original performance intent, or improve on original performance intent. Then the procedure is fairly direct:

  • Select most cost-effective solutions;
  • Administer repairs;
  • Install new and/or better equipment;
  • Retest;
  • Document updated performance of the system; and
  • Conduct training for maintenance staff on operation of the updated system.

Who Gets the Call?

Selecting a contractor to perform any necessary repairs is another critical piece of the pie. Too often, an owner calls on a general contractor to perform these services, believing that since the contractor managed the construction, the contractor should be able to handle the “reconstruction.”

The problem lies in the word “general.” Building systems are a specific component of a building which need to be evaluated and restored by a specialist. Control contractors should repair controls. Piping contractors should work on the piping systems. A sheet metal contractor should be employed for ductwork defects. Overseeing these various specialists should be a mechanical construction management firm. Why not just let a general contractor hire the mechanical manager? Because it only creates a larger chain of authority, with layers of communication begging to be misinterpreted.

Proving it in School

A school district in a small town contacted a commissioning firm when severe mold problems arose in its 20-year-old middle school. A subsequent investigation found, among other things, that all of the fresh air vents in the building had been shut off and that the systems were not operating as originally intended. When various complaints about building temperature had arisen over the years, the maintenance personnel’s response had been to close the offensive vent. The controls for the system had not been repaired because the original controls manufacturer had gone out of business.

The commissioning firm was able to determine that the hvac systems, when new, had been installed correctly. The building would likely have functioned with few problems, had the support staff understood the maintenance requirements of the control system, been schooled in how the system should function, and understood the need to replace and/or repair the control system.

This example points out what will be an ongoing need in the next century for recommissioning. Like the school, many facilities have received bandaid treatment over the last 20 to 30 years and are now in need of serious repair and/or equipment replacement. In other cases, the purpose of the building has changed and the original building systems no longer meet the needs of the owner and occupants.


After the systems have been renovated and retested, they are once again turned over to the personnel who will operate and maintain them. Since staff members who lack systems training are often at the root of the problem(s) that necessitated recommissioning services in the first place, the need for detailed, regular training is evident. A program of preventive maintenance can also go a long way toward sustaining desired system performance.

Lower maintenance costs, improved productivity, higher employee and tenant retention, improved energy utilization, and fewer headaches (literally and figuratively) are just a few of the benefits an owner or facility manager can garner from a building which is operating at peak performance as designed. Recommissioning is an excellent tool for preventing problems and ensuring a well-run facility. ES