Retrocommissioning — the process of ensuring that all the mechanical systems in an existing building perform optimally, based on the contract documents, design intent, and the owner's operational needs — can be used for a number of different purposes.
Once its value has been established, several steps must be followed to ensure that the retrocommissioning project will be successful.
STEP 1: Define and document a goal. While a building owner or manager may be sold on the concept of retrocommissioning, be sure that what you intend to deliver meets with his or her expectations. Make sure that the owner's expectations are realistic. If the goal is reduced energy consumption, perform a "sanity check," with simple metrics available from the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) or the Building Owners and Managers Association (BOMA), to confirm that the expectations are reasonable and attainable. Don't promise what can't be delivered.
STEP 2: Assess the building's intended use, and design versus actual building usage. It's quite common to find that the design engineer intended for the building, or a section of the building, to be used differently than it's being used now. Here are some examples we’ve seen at Geauga Mechanical:
- a former laboratory space converted to offices, without compensation for changes in HVAC requirements;
- a school teacher’s lounge converted to a daycare center;
- storage space in a medical office building converted to a room for testing patients' cardiovascular abilities.
Changes in usage often require changes in HVAC capabilities. Make sure your retrocommissioning provides solutions for new space applications. Request that the customer inform you of any changes they make that will affect your retrocommissioning in the future. A thorough retrocommissioning can provide long-term benefits to your customers and their tenants. Help customers understand that it's a partnership, not a one-time "miracle" process.
STEP 3: Ask for and examine as-built drawings and air and water balance reports. These are critical to show how the system was set up and is operating following construction. It's possible you’ll be asked to retrocommission buildings that were never properly commissioned in the first place, or that may have systems that were poorly designed and/or installed.
STEP 4: Assess overall mechanical system condition. This is where "the rubber meets the road" for retrocommissioning.
- Evaluate the repair history of the mechanical system. What has failed, and how often? Is there a pattern?
- Evaluate the building’s utility usage history. If there have been large fluctuations from year to year, find out why.
- Evaluate occupant comfort history. Are there any ongoing comfort complaints?
- Evaluate all major components of the system. What's the condition of the ductwork? What degree of air leakage is there? Does the sizing and layout look right? Has the system been air balanced? Are there any leaks in the piping systems? How is the insulation? Has the water system been balanced? How up-to-date and effective are the controls? Is the operator comfortable with the controls? Are there operator overrides in the system that may be causing problems?
STEP 5: Document any changes you make. Once you have assessed the mechanical systems and decided on a plan of action, document the changes that you implement.
Making one change to a control setpoint or mechanical action can cause a "ripple effect" that affects other elements of the system, so it's important to know what you did and when you did it. If you find that there's a negative reaction down the line, it will be much easier to identify and solve if you document your steps.
STEP 6: Ask questions. If something doesn't seem right to you and your team, ask the owner. Did another HVAC company, or the owner's own maintenance team, make changes to the system, or certain components of it? If you don't ask, you could be missing a critical piece of information. This missing information could be very damaging to your efforts to retrocommission the building. On the other hand, it could also lead to a very satisfied customer if identified.
After performing these steps, you'll have a good feel for what's transpired over time in a building. Then, you can identify "low hanging fruit" (the retrocommissioning fixes that will have the most effect and provide the most bang for the customer’s buck), and begin knocking them down one by one.
Dan Slattery is service manager at Geauga Mechanical Company, Chardon, OH. He can be reached at 440/285-2000 x 205, or by e-mail at firstname.lastname@example.org.