Tips and tricks for commissioning, balancing buildings
CSE: When re- or retro-commissioning structures, what challenges do you encounter, and how do you overcome them?
York: Re- and retro-commissioning projects introduce the unique challenge of trying to understand how the facility was originally designed and also how it is currently operating. The existing documentation (design, record documents, and equipment information) is typically sparse or non-existent, and the CxA must rely on intensive field investigation and end user interview sessions to establish the baseline. In addition, system functional testing is problematic because the facilities are occupied. The CxA must be prepared to work off-hours and become creative with testing as to not interrupt the end user’s daily activities.
Bauers: The most significant challenge in retro-commissioning or re-commissioning is uncertainty. Simply understanding the nature and configuration of installed systems requires an iterative process of discovery. Dealing with the expertise, motivation, and resistance of the operating staff requires a subtle approach to engaging those individuals most knowledgeable in the character and operating challenges of a building system as full partners in the process. Finally, collaboratively constructing a process to both identify and quickly implement operating and deferred maintenance opportunities is essential to creating cultural changes that allow the implemented solutions to become a part of the culture of the operating building.
Szel: Challenges with retro-commissioning start with the scope of work. Clients understand the goals but often have difficulty preparing a good phased scope of work. Because of that, often the bids aren’t apples to apples and the client may not achieve the full expectations. Invariably with a re- or retro-commissioning project, the documentation is out of date, incomplete, or completely missing. Understanding how the system currently operates is critical. This is where the building controls vendor is the most helpful resource. The technician will be able to dig into the programming and extract the sequences of how the building is actually running. Don’t assume they can pull everything you need without direction, though. You will need to work with them and help with the documentation process—this will be invaluable later when you are discussing recommendations with the team.
Wolff: The first big challenge is a functioning control system. If the target building does not have a functioning DDC system, the challenge of improving functionality is almost impossible. Retro-Cx customers are usually interested in “low-cost/no-cost” solutions, and if the project does not have a DDC system or if the controls are incomplete or are in such a poor state that replacement is warranted, then low-cost/no-cost solutions are usually not available since the investment of a new or retrofitted DDC system is cost prohibitive. The second major challenge is that unless the building is fairly new, the documentation, if it exists, is usually unreliable. This can create challenges in every aspect of the existing building commissioning project. For this reason we typically recommend a multi-step approach to existing building commissioning that allows us to adjust the program as we go. The third challenge is one of identifying and understanding the purpose and goals of each retro-commissioning project. Why does the customer want to do retro-commissioning on his building? What is the goal? As the provider you need to know if they are interested in energy savings, operating improvements, both, or something else.
Feyler: The investigation phase is generally the most time-consuming and challenging. As-built documentation from the earlier design, retro-fitting, or improvement projects that may have taken place, construction final documents, auction trust closeout (ATC) documentation, and O&M manuals are difficult for the owner to provide. Additionally, have the system performance and operation been changed due to tenant complaints, general tweaking of the systems to answer the complaints, or a change of use within the building or spaces? These changes are almost always not documented on drawings or facility maintenance plans. Another challenge is the facilities maintenance plan—how well has the facility been maintained, and when was the last time sensors and meters were calibrated? Is there an existing testing and balancing report, or will there be a need to perform a existing condition air and water flow verification during the retro-commissioning investigation plan stage? Will the building envelope be part of the retro-commissioning plan to include the envelope in the investigation? Are the cold and warm calls due to the building envelope issues?