Glossary

Rack Density

Also known as: power density, kW per rack

The amount of power, expressed in kilowatts per rack (or per cabinet), that a data center's electrical and cooling infrastructure is designed to support for a single server rack.

Legacy enterprise data centers were typically designed for 3 to 8 kilowatts per rack using air cooling, but the rise of GPU-based AI training and inference clusters has pushed densities to 30, 50, and in some cutting-edge deployments over 100 kilowatts per rack, a level that air cooling alone cannot economically dissipate. Rack density is a critical underwriting variable because a building's mechanical design sets a ceiling on the density it can support without capital retrofit; a facility engineered for 8 kilowatts per rack cannot simply be re-leased to a high-density AI tenant without adding liquid cooling infrastructure, chilled water loops, or supplemental cooling capacity, and in some cases without derating the total leasable power. Investors evaluating older data center stock increasingly ask whether a building's shell, floor loading, and cooling plant can be upgraded to modern high-density standards at reasonable cost, since assets that cannot are at growing risk of functional obsolescence as demand skews toward AI workloads.