By Laurie A. Gilmer, P.E. - March 2006 - Energy Efficiency
Energy cost are constantly on the rise, and organizations’ resources are becoming increasingly limited. In an effort to keep energy costs down, maintenance and engineering managers have begun looking for ways to improve the performance of their facilities’ energy-consuming systems.
One way to significantly reduce these costs is through the process of retrocommissioning. The process offers managers an organized approach to identifying operating problems with existing facilities and systems, as well as opportunities for increased energy efficiency and reduced operating costs.
Retrocommissioning, much like commissioning for new buildings, is an organized process that identifies facility performance objectives, a methodology for testing and verifying those objectives are achieved, and documentation of the process. But retro-commissioning is performed on facilities that are already in operation, and it is typically in response to problems that exist within building systems.
The overall goals of the retrocommissioning process are to:
- verify and document that the key building systems are performing in accordance with the owner’s defined operational needs
- reduce both energy consumption and operating costs.
During the process, problems with building systems are identified, and recommendations for fixing the problems are made. The process can range all the way from very simple to highly detailed, but the bottom line is always the same: identify ways to save money through better system performance.
When to Retrocommission
Retrocommissioning typically is called for in response to operational problems in a facility. Among the timing issues manager should consider are these:
- System performance. Is the system performing as expected? Has there been an unexplained increase in building energy use in the recent past?
- Occupant comfort. Have building occupant complaints risen lately? What is the nature of these complaints?
- Changes to the facility. Have changes been made to the building systems that have not been verified or documented? Is the documentation of these changes beneficial?
- How critical is the performance of the building systems to the particular facility or area? How often must it be verified? Tolerances for systems operations in a laboratory facility will be much different from an office building.
There is no simple answer to the question of the cost of retrocommissioning. Costs for the process will depend on the type of facility involved, the complexity of its systems, and the type and number of systems that are going to be retrocommissioned. Typical costs for retrocommissioning can range from as low as $0.50 per square foot up to $2 per square foot.
The key to keeping costs in line is to identify, ahead of time:
- the goal of the process for the particular facility
- the type of information that the process should collect
- the type of recommendations expected from the process.
The results of retrocommissioning obviously will vary. Depending upon the problems identified and recommendations implemented, annual operating cost savings can range from $0.15 per square foot to $1.15 per square foot.
With this type of savings possible, the cost for retrocommissioning is relatively small. For example, a 100,000-square-foot facility with a retrocommissioning cost of about $88,000 — $0.88 per square foot — yielded an annual cost savings of about $20,000, or $0.20 per square foot. The payback for the retrocommissioning often is less than five years.
Selecting a Partner
The make-up of the retrocommissioning team depends upon an organization’s needs. The team typically includes a maintenance and engineering manager, key members of the facility operations and maintenance staff, contractors, and the retrocommissioning consultant.
Selecting a retrocommissioning consultant is an important decision because the firm will be the key partner in the process, responsible for coordinating and managing the overall retrocommissioning process. When selecting a retrocommissioning partner, managers should look for a partner that:
- has an organized approach
- understands the organizations’ needs
- has an experience base that can be applied to the facility in question.
Retrocommissioning can be as simple or complex as a manager wants it to be. But some areas of investigation will have a more significant impact on reducing energy use and operating costs. The number one area is building heating, ventilating, and air conditioning systems. HVAC systems account for the majority of building operating costs.
By concentrating on the performance of these systems, a manager can target the “low-hanging fruit” — those systems and components that make the most significant improvements to an organization’s bottom line. Common HVAC system problems identified during the initial stages of the retrocommissioning process include:
- loose fan belts
- leaking valves
- balancing valves that are not functioning properly
- thermostats and sensors that are out of calibration
- air balancing systems that are off
- variable-air-volume boxes that are not working properly
- economizer sequences that are not working as designed
- controls sequences that are functioning incorrectly.
Addressing these problems can quickly reduce a building’s energy use.
Once a manager and a retrocommissioning partner have identified system problems and the opportunities for energy savings, the manager must select the recommendations that will be implemented. Once this has occurred, the building systems should operate more efficiently and in accordance with the needs of the facility. And with the retrocommissioning plan and recommendations in hand, the manager has a baseline for measuring results.
The success or failure of retrocommissioning lies with answers to these questions:
- Are the building systems performing according to defined operational needs?
- Has the facility’s overall energy use been reduced?
- Have occupant complaints dropped?
Retrocommissioning is an invaluable tool that managers overseeing existing facilities can implement to produce results. When it is used effectively, the process can provide an organized approach for verifying system performance, improving energy efficiency, and reducing a facility’s overall operating costs.
Laurie A. Gilmer, P.E., CFM, is with Facility Engineering Associates (FEA) — www.feapc.com — a nationwide consulting firm that focuses on extending the life of and improving existing facilities.
Retrocommissioning can be a complex process because of its potential to cover a range of facility systems and equipment. But it also can be well worth the commitment of time and resources. Managers looking for more information on the process can check out these available resources: