Free cooling · Economizer
Using cool outside air or water to reject heat without running mechanical chillers, saving energy in mild conditions.
Current numbers
~45 °Cwarm-water inlet band (W40/W45) GB200 & Rubin target — enables near-year-round chiller-less free cooling
~3–5 °Ctypical CDU heat-exchanger approach temperature (lower = warmer facility water, more free cooling)
30–40%cooling share of total data-center energy that warm-water free cooling can largely eliminate