It sends "chilled water" (about 45°F) through the building to cool the air.
Large buildings don’t just use "giant air conditioners." They use a tag-team system: and Cooling Towers. Hvac Water Chillers and Cooling Towers
For skyscrapers or hospitals, air-cooled systems would have to be impossibly large. It sends "chilled water" (about 45°F) through the