Consulting-Specifying Engineer - April 2008 - (Page 44) Advanced Application Controllers provide energy-saving control algorithms for many applications and equipment diagnostics through on-board trending. Photo: Automated Logic Corp. building system? Again, the answers are very project-dependent, but need to be clearly specified and planned for in the overall DDC system design. A more complex system-to-system interface occurs when the engineer attempts to have multiple systems interoperate. This can be accomplished by using an open protocol allowing two different systems to share information. This also can occur between various “vintages” of one manufacturer’s versions or systems. Typically, the interfacing that occurs between various offerings of one manufacturer is handled by that manufacturer. The questions that need to be asked to effectively integrate different manufacturers are many and relatively complex (and probably the subject for a different article). As with equipment interfaces, key factors include the level of visibility and functionality available across systems. It is relatively easy to make visible specific hardware point values across systems. It is another level to expose “parameter level” details such as alarm limits, calibration values, overrides, tuning parameters, and similar factors across systems. These details may not need to be displayed across systems, but if it’s desired or required, it needs to be specified as it has significant network bandwidth, hardware, and set-up time impacts. Another detail to consider: What level of functionality would you expect? For example, can system A trend system B points? Can system A schedule system B equipment? Can system A alarm based on System B parameters? You should also consider the changing of set points, reset schedules, or other programming details between systems. Other details Training and documentation requirements are equally important factors in the design of the system. If this project is going on a site where the operators are inherently familiar with the system being installed, there may be the need for a demonstration and orientation-level training session only. More often, the DDC system may be new to the inheriting operators. This fact may require a brief assessment of DDC capabilities and needs as part of the project. If it’s a small project, the budget may not afford too much specialized training above and beyond what typically is provided. Conversely, a larger project may be the place to require advanced training on DDC systems for a given institution. Regardless, if system performance is to be maintained, operators need to be trained on the DDC system. Documentation also needs to be covered in the planning of a DDC system. Documentation requirements can cover how sub- mittals and shop drawings are organized and presented. It can cover details like addressing and point-naming conventions. Wouldn’t it be nice to see similar names for all the points on hundreds of air handlers across the same site or campus? Or to be able to look at a standard point addressing format and quickly know specifics about that point (such as building, system number, point type, etc.)? Documentation requirements could also include details on how graphic pages are laid out, and could require that these graphics be made part of the submittal and approval process. The key is getting the graphics reviewed and approved early in the process. Most DDC application engineers don’t mind customizing graphics for an owner as long as they do it only once. The above DDC criteria ideally would exist for every owner and could be used for every project. Unfortunately DDC master planning hasn’t received the same level of attention as IT infrastructure planning. Detailed planning documents exist to get a new building on the corporate, university, hospital, or county on local area network. If these details were not planned out, we would have less reliability, higher maintenance costs, and less secure networks—and ultimately business conducted through these networks would be less effective and efficient. What’s at the other end of our DDC systems and the HVAC systems they control? A significant portion of the energy consumption of the building, the quality of the air we breathe while in the building, and the productivity of the most important assets in the majority of buildings—its occupants. Shouldn’t these systems have a similar level of planning as our information systems? With the increased focus on energy performance of buildings, our carbon impact on the environment, IAQ, and building performance and persistence, maybe this planning finally will get the attention it deserves. Santos is a principal and co-founder of Facility Dynamics Engineering. He has directed the development of DDC/control master plans for numerous institutions and organizations. 44 Consulting-Specifying Engineer • APRIL 2008
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