Technical Retro-Commissioning is a process utilized to correct your building’s deficiencies and to improve its performance. Retro-Commissioning (RCx) is intended to be a low-cost method of providing the highest level of building performance without spending a lot of money on capital improvements.
Retro-Commissioning normally is initiated in response to poor system performance issues that the owner has not been able to fix. There are many reasons why these kinds of problems are persistent in buildings, one of them is that most technicians or service organizations cannot find the root cause of the issue and spend their time trying to correct symptoms instead of dealing with the root cause of the issue. T
he complexity of our buildings systems also contributes to persistent poor performance, especially for DDC control systems. Another contributing factor to poor performance is deferred maintenance issues and out-of-balance air and water systems. Any deferred maintenance will directly affect system performance.
What is Building Performance: Building performance is the quality of the indoor environment and the level of energy and water usage. By indoor environment we mean how comfortable the building is for its occupants for temperature, humidity, air flow drafts, air quality, and sound and vibration.
What are the main benefits of Technical Retro-Commissioning: The expected benefit of Technical Retro-Commissioning is that your building’s performance improves during the process of performing the RCx. Be aware that this is the main difference between a normal RCx project and a Technical Retro-Commissioning process.
Normal RCx or Existing Building Commissioning is a hands-off approach which is basically an expanded energy audit where no actual adjustment, optimization or system improvements are made. Technical Retro-Commissioning is a hands-on approach where the provider is responsible to actually make a difference in your system’s performance.
The possible benefits of Technical Retro-Commissioning include: • Improvement in occupant comfort allowing more productivity and happier occupants • Reduced future system maintenance and repair costs • Reduced energy and water utility costs • Improved operations requiring less operator time due to a lower amount of trouble calls • Increased expected lifetime of equipment and systems due to improved operation • Increased value of your building asset
Retro-Commissioning can be performed utilizing many different approaches as to who accomplishes the required tasks. The RCx process can be implemented by utilizing an outside consultant to perform all of the required tasks or it can be accomplished by using in-house expertise or a combination of an outside consultant and in-house expertise. The important thing is not who performs the tasks but that they are all performed.
If you are interested in establishing an in-house RCx team, your RCx consultant can provide a training program to train your staff on how RCx is performed. I have also operated these programs in the past by providing the owner with a commissioning engineer to lead their team in the RCx efforts. This allowed a full RCx effort with the lowest possible outside costs.
The basic steps in the retro-commissioning process are as follows:
1. RCx Contract
The RCx contract can be any kind of contract as preferred by the owner. Most RCx contracts are fixed cost or fixed costs for the discovery process with an allowance for quick fixes and deferred maintenance issue corrections. The contract can also be time & material based upon fixed labor rates. It is also possible to perform RCx under a guaranteed performance contract where savings from the process are guaranteed against the cost of the RCx.
2. Project Planning
Before starting an RCx project, a plan should be established for the goals of the project and how the project is to be implemented. If you have multiple buildings, it is also advisable to instigate a process to evaluate all your buildings to determine what buildings and in what order you wish to include them in the RCx process.
During this planning stage, a basic Current Facility Requirement (CFR) is created to document how the spaces are intended to be used, what their environmental conditions need to be, how many occupants are normally present and any other pertinent data that will affect how the RCx is implemented.
From the CFR and the goals of the owner, an RCx Plan is created that details how the RCx process will be implemented to achieve the goals of the project. The plan details what process will be used and by whom they will be performed. The plan may also contain a general schedule of the anticipated process.
3. Initial Data Collection
To start the actual RCx process, obtain all existing design drawings, system submittals, balance reports, energy and water utility bills for the last few years, copies of replaced equipment submittals or purchase details and summary reports of maintenance management reports, and copies of outside purchased maintenance contracts for what is included in their services.
4. Drawing and Design Review
Perform a drawing and design review of the existing systems. If original construction documents exist, review these to understand the original design intent and to compare with what you actually find installed. Review original control sequences to establish areas of concern that will require site investigation. From your review start an issue log for field investigation use.
5. Building System Assessment & Deferred Maintenance Assessment
As the first field test, inspect each piece of equipment as to its general condition, its operating condition, estimate its current life expectancy, record any obvious operating issues or deferred maintenance issues and record its present load, power usage or water usage.
6. Data Logging Space Conditions
To evaluate system performance, it is important to have a reliable history of the actual space conditions. Normally, we place calibrated data loggers in each control zone when we do the system assessment. These data loggers are left in place for at least two full weeks to gather both week day and week end data.
It is possible to use the existing control system for this data but you must first calibrate all sensors utilized before you can trust the data. Another issue with using the control system is it normally does not have the points we need to record for the space, temperature, humidity, and lighting level.
7. Operator and Occupant Interviews
During the assessment perform operator and occupant interviews. The purpose of the interviews is to listen to their evaluation of their space and to learn what has been done in the past to alleviate any issues.
8. System Testing
From the design review, energy audit, field assessment, space data logs, and the interviews we can determine which systems are not performing correctly and what testing is required to discover the root cause of the issues. System testing includes any or all of the following: a. Control system point and sequence testing b. As-found balance readings c. Energy and water usage tests d. Operating procedure review
9. Root Cause Analysis
From all the data and testing performed, determine the root causes of the issues discovered. Many times, one solution solves more than one issue. During this process, recommendations are created for future capital measures to improve future performance.
10. Quick Fixes and Deferred Maintenance Issue Elimination
During the assessment or testing discovery process, any quick fixes found are fixed so they do not hide the true root cause of the performance issue. A quick fix is defined by the contract and is usually something that can be fixed without material in a few minutes. Examples of a quick fix are adjusting damper linkage, re-attaching a flex duct, adjusting a damper or valve, or making a small control adjustment.
Depending on how the RCx contract is configured, all deferred maintenance issues are corrected as they are found. Normally, it is preferred that the owner’s staff or outside contractors perform the deferred maintenance issues. Deferred maintenance issues consist of:
- Changing Filters
- Cleaning Coils & Fans
- Changing fan belts
- Repairing dampers or valves
- Cleaning strainers
- Cleaning tube bundles
- Cleaning cooling towers
11. System Optimization & Corrections
Near the end of the RCx process, when all deferred maintenance issues are corrected, all quick fixes completed, all issues have been analyzed, and the root causes identified, we start the process of RCx corrections or optimizations. Systems are optimized by trimming the air and water flow balance, calibrating sensors or devices, and adjusting control sequences and setpoints as required to improve system performance.
12. Operator Training
Depending upon what changes or corrections were made, operating instructions are updated and operators are trained and instructed on the updated operations and maintenance practices for the systems.
13. Performance Tracking and Evaluation of the Results
As an important part of the RCx project, the owner’s performance tracking system is updated and reviewed for correct tracking for future system performance. If the owner does not have an operating tracking system, a manual system will be provided, set up, and operators trained on its use. It is critical that operators know how they are doing, and without a performance tracking system, you will never be able to improve performance.
14. Final RCx Report
After all work is complete, a final RCx report is issued. This report contains documentation of all work completed and includes a list of recommendations for future capital projects that will improve future performance. The report contains estimated budgets, anticipated cost savings, and ROI for each recommendation.
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