Internet Initiative Japan Inc. (IIJ) has announced plans to begin construction on a third server building at its Shiroi Data Center Campus (DCC) in Chiba Prefecture, targeting the growing demand for AI-ready, energy-efficient data center infrastructure. Construction is scheduled to begin on June 1, 2025, with operations slated for fiscal 2026. The expansion will support IIJ’s portfolio of cloud, security, IoT, and MVNO services, and is designed to accommodate high-power AI workloads with up to 25MW capacity.
The Phase 3 facility will span 5,400 square meters and support 1,000 racks, incorporating direct outdoor air cooling and a “liquid-cooling ready” design. This includes reserved space and pipe routing for DLC (Direct Liquid Cooling) systems, preparing the facility for GPU-intensive servers used in AI applications. Flexible ceiling structures will enable future reconfiguration of rack layouts to accommodate emerging thermal and power demands. The building will also apply hybrid structural design principles to support varying floor load requirements between server and electrical zones.
IIJ is also integrating lessons learned from an ongoing joint research initiative on ultra-high-efficiency AI computing infrastructure. As part of its commitment to carbon neutrality, the new facility continues to adopt energy-saving technologies including wall-mounted blowers and a three-phase, four-wire UPS system for optimized power distribution.
- Construction on Phase 3 begins June 1, 2025; operations expected in FY2026.
- 5,400m² building with 10MW incoming power (expandable to 25MW), 1,000 racks.
- Supports AI workloads with “liquid-cooling ready” infrastructure.
- Flexible ceiling layouts for liquid-cooled rack deployments.
- Continues IIJ’s energy-saving approach with outdoor air cooling and efficient UPS.
- Part of an ongoing research effort on ultra-efficient AI data center design.
“The Phase 3 building reflects our ongoing commitment to meet future infrastructure demands driven by AI, while maintaining top-tier energy efficiency,” said an IIJ spokesperson.
