University of California, San Diego

Dynamic control and VFDs reduce retrofit costs and yield immediate savings.

29 percent

reduction in electricity use

62 percent

reduction in chilled water

52 percent

reduction in hot water use

“The achievement of substantial energy and cost savings with few disruptions to operations is a useful and replicable strategy to consider for any CAV, non-lab building on any campus.”
– From the case study’s executive summary

Instead of replacing the constant air volume air delivery equipment in this heavily used library, a digital controls retrofit and new variable frequency drives allow significant fan speed reductions and better control, resulting in lower retrofit costs and immediate energy savings of 23 percent.

The UC San Diego wanted to retrofit the Geisel Library to meet a campus-wide commitment to save 12 million kWh in 2012. One of the most heavily used buildings on campus, the library serves 1.4 million students and visitors annually. Its inverted pyramid tower hides a vast area of subterranean stacks and reading rooms added during a 1994 renovation.

Because the building used so heavily, a VAV conversion and its associated construction project was less than desirable. The Vigilent system allows the air handlers to behave more or less like a VAV system with fewer interruptions to users and a lower cost. The school expects to achieve approximately 60 percent of the savings it would have achieved with a full VAV retrofit, but at 30 percent of the cost.