Precision Control Plays Role in University’s Renovation

ROHNERT PARK, Calif.-Sonoma State University proposed converting the original Ruben Salazar library into a multi-use facility. The project required careful consideration, from selection of the 106kW solar photovoltaic system to the valves and actuators that control water flow and damper operation in more than 100 zones.

Pacific Gas and Electric Company has awarded the Ruben Salazar building and the university $703,200 in rebates and incentives over the last eight years for this and other energy-efficient projects.

The Ruben Salazar project earned Sonoma State University an ASHRAE Regional X Award in the category of “Institutional Building, Existing.” The library has also caught the attention of the California Energy Commission and the Lawrence Berkeley National Laboratory, which has hired the Davis Energy Group to further study the performance of the building.

Principal engineer Tony Costa, of Costa Engineers Inc., was aware of the campus goals and budget when selecting the characterized control valves and actuators that would be used on the VAV reheat coils, dampers and chilled water-cooling coils. The valves and actuators played an important role in the system’s overall efficiency, as they enable the building to maintain 100 percent outdoor air and carefully maintain accurate flows to maintain comfort at the lowest possible pump speed.

Costa knew from experience that Belimo’s Characterized Control Valves (CCV’s) were accurate and, along with direct -connected actuators and DDC controls, would enable the university to continuously monitor every valve in the building and adjust pump flow rates based on valve position. Minimum required flow rate is attained when all zones are satisfied and no control valve is more than 90 percent open. Ordinarily, an engineer might select globe valves for this type of application. However, the engineering firm had tried the CCVs shortly after they were introduced to the market in 1999 and subsequently realized they could get accurate control from the “ball-type” control valve at less expense, size and weight.

According to Costa, the design of the Sonoma control system is a step above others because of the precise control it allows over individual zones. System VFD’s react to an “average” in pressure change, rather than the individual position of each valve. However, at the Ruben Salazar building, operators know exactly which valve is at its worse-case scenario and can drive the pumps to meet that particular condition without consuming unnecessary energy.

These were important considerations for the electrical contractor, as well, who not only installed the control system, but also services it. Syserco Inc. has installed more than 1,000 systems in Northern California and fully supported the CCV selection. “We wanted a valve and actuator that would provide proportional control for better comfort for our customer,” said Phil Herve, Account Manager for Syserco’s North Bay office. “The CCV offered the service and reliability we wanted, plus a full two-year warranty from the date of commissioning.”

Fully operational since late 2002, the system has been able to maintain an indoor temperature of 72 F to 75 F without help from the chilled water system. The university’s own observations indicate that the total system design has reduced peak load by almost 400 tons on the hottest days of summer.