Modelica Library for Building Heating, Ventilation and Air-Conditioning Systems

Publication Type

Conference Paper



The data center in this study had a total floor area of 8,580 square feet (ft2) with one-foot raised-floors. It was a rack lab with 440 racks, and was located in a 208,240 ft2 multi-story office building in San Jose, California. Since the data center was used only for testing equipment, it was not configured as a critical facility in terms of electrical and cooling supply. It did not have a dedicated chiller system but served by the main building chiller plant and make-up air system. Additionally, it was served by a single electrical supply with no provision for backup power. The data center operated on a 24 hour per day, year-round cycle, and users had all hour full access to the data center facility.

The study found that data center computer load accounted for 23% of the overall building electrical load, while the total power consumption attributable to the data center including allocated cooling load and lighting was 30% of the total facility load. The density of installed computer loads (rack load) in the data center was 63 W/ft2. Power consumption density for all data center allocated load (including cooling and lighting) was 84 W/ft2, approximately 12 times the average overall power density in rest of the building (non-data center portion).

For the data center, 75% of the overall electric power was the rack critical loads, 11% of the power was consumed by chillers, 9% by CRAH units, 1% by lighting system, and about 4% of the power was consumed by pumps. The ratio of HVAC to IT power demand in the data center in this study was approximately 0.32.

General recommendations for improving overall data center energy efficiency include improving the lighting control, airflow optimization, and control of mechanical systems serving the data center in actual operation. This includes chilled water system, airflow management and control in data centers. Additional specific recommendations or considerations to improve energy efficiency are provided in this report.


7th International Modelica Conference

Year of Publication