An existing raised floor data center with 5,000 kW of information and communication technology equipment load capacity was expanded in 2004 to accommodate an additional 3,000 kW of high-density load. The additional space needed to serve higher density racks of up to 16 kW per rack with an average density of 8 kW per rack. This project demonstrated the applicability and cost effectiveness of variable airflow in data centers. CO₂ produced was decreased by 2,000 tons/yr (1,814 Mg/yr) with a direct energy savings of 16,210,930 kWh/yr. This is an ASHRAE Technology Award.