Last month, this column introduced the issue of data sharing between equipment on-board controllers and a central BAS. We have reached a point in the evolution of building systems control and integration where there is actually more information available to be shared than is typically useful to the building owner/operator. In order to avoid data paralysis, decisions need to be made by project teams regarding which points are worth acknowledging between the equipment controllers and the BAS and which points can be ignored.
Last month’s column suggested a design-phase approach to addressing this situation in order to clarify which points must be shared in either direction (e.g., equipment controller-to-BAS or BAS-to-equipment controller) and what will be done with those mandatory points after they are shared. If that does not happen, dealing with the issue will be pushed into the construction phase of a project. In either case, the commissioning professional may be put in a position of facilitating the discussion and decision-making process.
Ten years ago, the construction phase challenge was making sure the onboard equipment controllers could actually communicate and share information with the BAS. That often required special gateway equipment that may or may not have been clearly specified in the bid documents. Today, communication between systems has improved significantly as major equipment controllers have the required gateways built-in or are otherwise configured to communicate easily with major BAS. In fact, many equipment controllers can now share everything they have with the BAS, and that’s where the potential data paralysis occurs.
The BAS does not need everything from the equipment controllers, and the building operators do not want to be burdened with data that is not of value. When equipment manufacturers make all their data points available to the BAS, the BAS needs to be programmed to “take” only the valuable points. Who decides what is valuable for each project? If that isn’t clearly defined by the designers in the bid documents, it will end up being the BAS contractor.
This is where the third-party commissioning professional comes in. First of all, the commissioning professional will focus on documentation of the shared points in the BAS submittal. The BAS contractor should document exactly which equipment points are to be imported into the BAS for active monitoring. That list is essentially an extension of the BAS system points list. However, this part of the points list contains the integrated or hard-wired points that come from other control systems in the facility.
The commissioning professional should encourage the building owner/operator to have a voice in this decision. Some operators will have a large appetite for data and will have the resources to dedicate to its monitoring. Many operators, on the other hand, barely have time to look at the BAS under normal circumstances and, when they need to, they do not want to have to wade through a lot of extraneous information before they arrive at the critical stuff.
The level of technical expertise and expectations for hands-on troubleshooting on the part of the building operators are other factors to take into account when deciding how many and which points need to be brought into the BAS. If the building operator would find a point interesting to have available remotely in order to determine a plan of action for system performance problems, then it should be brought into and appropriately displayed in the BAS. If the building operator wouldn’t understand what a point is and how to interpret its reading, there is limited value to bringing it into the BAS. It is important to remember that all equipment data points will also be available locally at the user interface to the equipment controller itself.
Once the points of interest are identified, it is critical that the BAS contractor’s submittal be clear on exactly what will be done with each point. Some typical options:
•Monitoring only, in which case the point needs to be incorporated into one of the BAS graphic pages
•Monitoring and alarming only, in which case alarm limits need to be defined in addition to incorporating into a BAS graphic page
•Control point integrated into a BAS control sequence, in which case the affected BAS sequence should be clear on what the BAS will do as the point changes
This all sounds very logical and straightforward, but it is a major challenge in the commissioning process. I believe this is primarily because it is not a normal project delivery process. No one has historically been responsible for this detailed systems integration, and the commissioning professional often ends up playing this role in the course of obtaining answers to questions regarding how the systems will work and what the user interface will be. ES
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