Ashrae Journal - November 2008 - (Page B15)

pneumatic/electric network between the plant and nearby hardwired points, separate independent computer hardware buildings that could remotely monitor and adjust adjacent and software devices, and occasionally through expensive building HVAC systems. Photo 2, shows the College’s first proprietary and rarely reliable integration devices. Network attempt at an operator workstation (OWS) graphical user communications were through low-speed twisted-pair cables, interface (GUI). pulled through conduits that followed the central plant distriEach building on the Rockville campus had hot water con- bution system to each building, while remote communication verters, decentralized chillers and cooling towers with manually access was through dial-up modems. selectable, pneumatically actuated summer/winter changeover. Controls were specified, furnished, installed, and maintained The late 1960s saw the redevelopment of the Takoma Park/ by a single, sole source vendor, using proprietary products. NorSilver Spring campus, which included self contained packaged mally, public institutions such as the College require competitive terminal air conditioners (PTAC) and rooftop mounted pack- procurement of goods and services. However, in the early days aged DX constant volume systems with “black box” electrical several factors drove us toward sole source procurement. controls. First, the College was trying to successfully introduce a new The College built its newest campus in Germantown, Md., and complex technology while minimizing disruption and enin the late 1970s and responded to that decade’s energy crisis suring ownership by the O&M staff. Unlike some larger instituby designing their buildings with what were then state-of-the- tions who manage controls with a separate controls group, we art technologies. Included were exterior envelope insulation chose to manage our controls with the people who are directly systems, large overhangs for passive solar control, double pane responsible for answering the hot and cold calls, the O&M staff. operable windows for natural ventilation and daylighting, roof The O&M staff was trained on a standard platform using standaylight monitors, efficient lighting systems, water source dard tools while their capabilities were supplemented by service heat pump loops with thermal agreements with the vendor. storage tanks, and centrifugal Expansion of the proprietary chillers providing cooling to DDC into other buildings not the building’s central core. scheduled for renovation was Large rooftop-mounted flat coordinated with the vendor by plate solar thermal arrays and the O&M staff and funded from underground thermal storage their operating budgets. tanks with backup electrical Second, since our campuses boilers provided heat to the were small, and we had central plant distribution systems therheat pumps, heated domestic mally communicating with our hot water and the swimming buildings, it was necessary to pool. Controls consisted of time have the ability to communicate clocks and electrical controls. with the building systems from College-wide, controls were a the central plant. Controls at the mixture of non-DDC technoloPhoto 2: 1960s vintage central plant networked pneumatic operatime lacked a common commugies and manufacturers, which tor workstation graphical user interface. nications protocol, and if you were competitively procured and serviced by College operations and maintenance (O&M) wanted to use different vendors, you either wrote your own software drivers as Mike Newman and his controls group did staff and various controls contractors. at Cornell University or you hardwired monitoring and control Introduction of DDC points between systems. Neither of these options was desirable Direct digital controls were introduced incrementally in the so we stayed with sole source controls. latter half of the 1980s. Whole building installations began in the In the latter part of the 1990s, the College partnered with early 1990s with the construction of major new and renovated NIST by pproviding access to our DDC systems and assisting buildings and central chilled water and hot water plants on the in downloading actual system trend data that was used to test Rockville and Germantown Campuses. The central chilled their algorithms for rule-based fault detection and diagnostics water plants with ice storage, ammonia rotary screw chillers, (FDD). Faults were examined and verified in the field and repairs and engine-driven chillers with heat recovery used the digital were made as necessary. Although those first algorithms were capabilities of the computer to orchestrate energy and demand external to the controls system, later work would embed the management automation sequences not possible with previous algorithms directly into control devices. This was the first time technology. Figure 1 shows the chilling equipment in our central that we used the computer capabilities beyond the traditional plants integrated through the DDC system. controls model and it opened our eyes to some of the untapped Early integration for monitoring and control was through opportunities of this computer resource. November 2008 B A C n e t ® To d a y | A S u p p l e m e n t t o A S H R A E J o u r n a l B15

Table of Contents Feed for the Digital Edition of Ashrae Journal - November 2008

Ashrae Journal - November 2008 Contents Commentary Industry News Meetings and Shows Feature Articles Reducing Data Center Energy Consumption Building Sciences Feature Articles Sustainable Nature Center Emerging Technologies Special Products Washington Report Special Supplement: BACnet® Today BACnet® Goes Green Seeing the Light with BACnet® BACnet® on Campus BACnet® for Net Zero Analyzing BACnet® BACnet® at Xerox Campus BACnet® in Europe BACnet® for Green Library BACnet® at the University of Minnesota: Flexibility, Interoperability InfoCenter Product Showplace Classified Advertising Advertising Index

Ashrae Journal - November 2008

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