Specifying building automation, control systems for new, existing office buildings
Office buildings might seem like simple structures from the outside, but engineers engaged in such projects know they can be highly complex. This Q&A covers building automation systems (BAS) and controls.
J. Patrick Banse, PE, LEED AP, Senior mechanical engineer, Smith Seckman Reid, Houston
Robert Ioanna, PE, LEED AP, Vice president, Syska Hennessy Group, New York City
Douglas Lacy, PE, LEED AP BD+C, Senior associate, ccrd partners, Dallas
CSE: What factors do you need to take into account when designing building automation systems (BAS) for an office building?
Banse: Several factors, including energy codes, remote access and adjustability, 24/7 space and equipment monitoring, along with measurements, come into play. Some tenants want the ability to turn on their office suite lights just by entering their card key into the building parking garage. This may also activate the suite HVAC system so that air movement and temperature control are available when they enter the suite. It depends upon the sophistication of the BAS and its ability to integrate with security and lighting systems.
Lacy: When choosing a BAS system for a multi-tenant building, it is important to specify an open protocol that provides flexibility for future additions and has the capacity for all the current and future points necessary for the complete build-out. Proprietary systems tend to both limit competition and increase the cost of upkeep and expansion of systems over the life of a facility.
Ioanna: The key in designing a building management system (BMS) for any facility is to understand the level of monitoring each system requires and the types of specialized systems or spaces each floor contains. If any critical systems are known, certain BAS design considerations must be provided appropriately. Robust and redundant BAS instrumentation, self-healing ring network with managed switches, redundant sensors, and failure scenario logic must be accounted for in the equipment sequence of operations.
CSE: Do you find your firm obtaining additional contracts to work with the operations and maintenance (O&M) staff after the building’s BAS has been designed to ensure it’s performing as intended?
Lacy: Yes, we have seen more interest in this service line. With more facilities seeking sustainability certification goals such as U.S. Green Building Council LEED, Green Globes, and others, the desire to fine-tune and validate system performance is a key focus of ccrd’s commissioning and energy groups.
Banse: We sometimes are able to provide commissioning services for some projects through a third party, not part of the design team.
Ioanna: Many clients request our services after the base building design has been completed. We have been writing O&M manuals for equipment or systems, maintenance operating procedures (MOPs), and emergency operating procedures (EOPs). Retro-commissioning services are increasingly popular way to verify the BMS is operating the building mechanical systems at peak efficiency throughout the facility’s lifecycle. We often are asked to help provide the client with “step by step” procedures during maintenance windows or during emergency situations.
CSE: What new types of controls are you specifying into office buildings? Is the demand for personal control increasing? Are owners requesting ongoing measurement and verification?
Lacy: The technology and devices types that are being included today have been available in the market for some time; however, due to the desire to track sustainable metrics, we are finding more opportunity to use a wider variety of control strategies in office design. Strategies such as outdoor air monitoring, duct pressure reset, supply air temperature reset, and energy totalization packages are now commonplace where they were previously reserved for institutional and critical environment clients. Personal control can be a double-edged sword. While having occupants control their temperature is desirable for occupant satisfaction scores, having occupants with close adjacencies be able to adjust the temperature requirements much more than approximately 3 F may cause ”false loads” in a system or may cause two zones to ”fight” each other. Direct adjustment of airflow may also impact ventilation air reaching the occupied zones. With more facilities moving to a totally open concept, careful consideration of construction type, air distribution device location, and the likelihood of future occupant or wall relocations should be carefully considered during design before prescribing a unilateral personal control strategy.
Ioanna: Internationally more prevalent and slowly making its way into our domestic market is intelligent building systems (IBS). The goal of an IBS is to manage and control disparate systems on a common platform. Convergence and automation are two key principles to today’s building technology design. Data, voice, security, video, entertainment, wireless systems, HVAC, lighting, electronic building controls including green technologies, and audio/visual elements running on one infrastructure sharing ubiquitous networks that are robust, redundant, and secure are possible to achieve when planned and executed with the common goals in mind—manage and control. The IBS uses an Internet protocol (IP)-based IT network infrastructure for control system communication. Fully networked systems transcend integration and achieve system interaction with traditionally independent systems. By using the IT network, these systems can work collectively to optimize the building’s performance. Each converged system residing on the IBS network shall use the building’s Ethernet network. A single, redundant topology will mitigate downtime by providing alternate means of traffic flow.
Banse: More wireless devices and technology and adaptable and easily changeable BAS programming are two that come to mind. We see more demand for proper system control and function than for personal control—make the systems work within design parameters. They want the ability to monitor and record utility use of chilled water, airflow, domestic water use, and electricity use on a floor-by-floor and a tenant-by-tenant basis.