Building automation, controls in mixed-use buildings
Engineering mixed-use buildings is a fine art—specifiers must combine multiple engineered systems for several business and residence types into one structure. Building automation and controls can be complex, and system integration is key.
Robbie Chung, PE, LEED AP, Senior associate, Environmental Systems Design Inc., Chicago
Raymond Holdener, PE, Senior associate, Dewberry, Fairfax, Va.
Andrew Lasse, PE, LEED AP, Associate principal/senior mechanical engineer, Interface Engineering, Portland, Ore.
Gary Pomerantz, PE, LEED AP, Executive vice president, building systems, WSP, New York City
John Sauer, PE, LEED AP, Senior director, BSA LifeStructures, Indianapolis
LeJay Slocum, Assistant director, Atlanta regional office, Aon Fire Protection Engineering Corp., Suwanee, Ga.
CSE: What factors do you need to take into account when integrating automation and controls systems on mixed-use projects?
Pomerantz: Depending on how integrated or separate the building constituents choose to be, the automation systems can be fully integrated or entirely separate. The only exception to this is the fire alarm system, which must be integrated by code and good practice. Typically in mixed-use projects, each constituent has an independent system that is able to communicate critical information between them. The more integrated the MEP systems are with each other, the more integrated the building management system (BMS) also is. For example, if a common heating and cooling plant is used between the constituents, then the BMS tends to be more integrated such that the operation of these plants can be more easily optimized.
Chung: The delineation of the network backbone needs to be carefully considered between building usages with multiple owners or engineering staff. Early confirmation should be made on what the end-user intent will be to ensure each operator will have his or her own workstation and network associated to the respective equipment as required. Network security is also a hot topic that should be thoroughly evaluated to ensure the risk of being hacked is minimized. If a single building automation system (BAS) is used across multiple users, secure access should be carefully analyzed.
Lasse: The first question that needs to be addressed is whether to use a full building automation system (BAS) or stand-alone controls. This will depend on the uses for the building, the owner’s expectations, sustainability and metering targets, as well as the budget. We’ve found significant cost savings in stand-alone low-voltage controls on mixed-use residential projects that are not implementing a central HVAC system. However, projects need to be looked at holistically—a full BAS can provide a higher level of flexibility, troubleshooting, metering, and trending to provide valuable feedback for building owners, and is a must for central plant systems in mixed-use buildings.
Holdener: An overall management system should be planned for at the beginning of the project so that the building as a whole can use the same automation system. Therefore, the system must be specified so that it is an open protocol system that can be connected to various types of equipment so that all of the systems can work together. The system must be specified as expandable for the future.
CSE: What aspect of building automation systems (BAS) is most overlooked?
Holdener: Centralized BAS monitoring and control of individual dwelling unit HVAC systems, particularly where dwelling units tend to be unoccupied for extended periods of time and the HVAC system can be shut down entirely. For example, a condominium unit owner in a northern climate vacates to a southern climate for the winter months, turning off the HVAC system so the interior space conditions can reach relatively low temperature conditions depending on the outdoor ambient and adjacent space conditions. If that condo unit gets too cold, adjacent walls, floors, and ceilings can experience higher than expected heat transfer from the adjacent warmer spaces. If that condo unit gets cold enough, piping could burst. It would be beneficial for the BAS to have an interface with each condo unit’s HVAC system to monitor and control the system to maintain reasonable indoor temperature conditions at all times. Many times, the BAS controls the central HVAC system and equipment (cooling towers, pumps, boilers, “common area” air handling units, etc., for a water-source heat pump system), but the dwelling unit heat pumps have stand-alone controls so are not controlled or even monitored by the BAS. Energy monitoring of utility meters and submeters is another area commonly overlooked or deleted from the BAS during the VE process.
Pomerantz: Most often overlooked is the real-world operations of buildings and how building operations staff actually use BMS systems in their buildings. Operations staff tend not to operate the buildings on fully automatic operation because they know certain nuances of their buildings and how they are occupied and used.
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