A Case Study of Efficiency and Capacity Upgrades to the Earl Warren Hall Data Center at the University of California, Berkeley

Eric Soladay, P.E., LEED AP®, Integral Group

A case study of the Earl Warren Hall Data Center at the University of California, Berkeley, will be presented. The existing data center, cooled by traditional DX Computer Room Air Conditioners with a raised floor and no aisle containment, had exceeded its power and cooling capacities. On design days, the outdoor condensing units (mounted on the roof) overheat and supply air temperatures are not able to be maintained. Higher density racks, at 10 kW per rack located in two rows, experience temperature problems during these conditions, indicating the limits of a traditional raised floor installation.

A water-side economizer system is being added with a cooling tower, heat exchangers, pumps and rear door heat exchangers on the most heavily loaded racks, substantially reducing the energy use of the facility. A corresponding reduction in peak load on the CRAC units allowed additional servers to be added to the data center. Further, the generally dry weather in Berkeley allows the cooling tower system to alleviate the over-temperature situation with the condensing units. At high dry bulb temperatures when the condensing units struggle, the evaporative tower is at full capacity. Alternatively, on moderate temperature but humid days when the tower is only providing partial economizing, the condensing units are able to perform without problem.

When the project is complete later this year (all done while the existing data center remained in operation!), the data center's annual PUE will drop from 1.5 to 1.2, saving 20 percent of its annual electrical cost.


Eric Soladay is an innovative, goal-oriented mechanical engineer responsible for the procurement, management, and design of building engineering system projects with architectural and social significance, sustainable and efficient systems, and cost- and maintenance-conscious designs. As high-technology team manager, Mr. Soladay is responsible for the design of all high-technology projects and commissioning for all projects. As project manager and mechanical engineer of record at Integral Group, Mr. Soladay has led several significant projects, including a planned LEED Platinum retrofit of a historical laboratory building, a 180,000 square-foot data center with groundbreaking energy-efficient design, a 190,000-square-foot mixed use retail/commercial development in Palo Alto, California, and the Packard Foundation Headquarters, a 30,000-square-foot commercial/institutional zero-energy building.