HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Energy and Power Management, Distributed Control TrendsBuilding-wideController TrendsAmong the trends in building-wide control has been the drive forstandard communications. Early innovators that acted without generalindustry consensus include IBM with its Facility Automation and CommunicationNetwork (FACN) and others from the German and Canadiangovernments.Another trend at every layer of the control architecture has beenpeer to peer control. This technique is meaningful for building-widecontrol since it distributes the critical network functions to multiplecontrollers. The concept improves the integrity and reliability of thesystem. Although this type of controller can be complex, the cost premiumfor peer control is not significant due to the advances in electronicand microprocessor-based technology that result in greater functionalityat less cost. Microprocessor technology is at the heart of building-wideand individual control advances.Another related building-wide controller trend is integration at thefunctional level. There has been a movement toward integrated controlbetween systems with different functions such as security and buildingcontrol systems.Other trends in building-wide control include easier to use programmingand monitoring systems and PC-based central operator interfaceswith simple user interfaces.VAV Distributed ControlMost Variable Air Volume boxes include distributed controls. Peercontrollers can be used for continuously interrogating the network forsequences such as morning warm-up. This feature would have beencentralized in older systems. A single condition such as outside air temperaturemight have been monitored, and the building-wide devicewould make a decision on start time based on this data and a storedsequence. When start up was required, that controller would signal thestart of the sequence. With integrated control of this type, each controllercan make independent decisions based on building-wide data as well aslocal controller data. This results in more reliable and effective controlsystems.©2001 by The Fairmont Press, Inc. All rights reserved.