{"id":"cooling-plant","level":"datacenter","name":"Facility cooling and final heat rejection","shortName":"Cooling plant","role":"Carries heat from IT equipment to the outdoor environment or an approved reuse path.","description":"Heat removed from a processor has not vanished; it moves through successive thermal interfaces and fluid or air circuits. The facility cooling chain eventually rejects that heat outdoors or directs it into a useful heat-recovery application. Depending on climate and design, equipment can include heat exchangers, dry coolers, cooling towers, chillers, pumps, and air-handling systems. The atlas follows one unit of heat from the rack to its final destination and keeps water flow distinct from electrical energy use. Different arrangements trade energy and water consumption differently, so liquid cooling alone does not determine the total environmental footprint. Facility performance must be assessed across the complete heat-removal system and its operating conditions.","specs":[{"label":"Energy balance","value":"Heat is transported and rejected","context":"Cooling does not destroy energy."},{"label":"Equipment mix","value":"Design- and climate-dependent","context":"No universal requirement for every listed component."},{"label":"Water-use metric","value":"Liters per kWh of IT energy","context":"Site water-use effectiveness has a defined system boundary."}],"interfaces":[{"name":"Rack and facility return loops","direction":"in","signal":"Collected heat"},{"name":"Environment or reuse system","direction":"out","signal":"Rejected or recovered thermal energy"}],"tradeoff":"Cooling choices trade energy, water, and operating range. Local climate and system boundaries change the comparison.","whyAI":"Cooling capacity constrains sustainable compute density. The building must carry away the heat generated by active hardware.","related":["cdu","rack","power-shelf"],"sources":[{"title":"US Department of Energy — Data-Center Cooling Water Efficiency","url":"https://www.energy.gov/cmei/femp/cooling-water-efficiency-opportunities-federal-data-centers"}],"scale":"Building-to-campus thermal infrastructure","kind":"cooling-plant","mechanism":["Collect heat from IT and supporting equipment.","Transport it through the selected facility cooling stages.","Reject or reuse the heat while accounting for the supporting energy and water flows."],"misconception":"Liquid cooling at the chip does not by itself imply zero water use or zero cooling energy across the facility.","check":{"question":"Where does removed processor heat ultimately go?","options":["It is erased by the coolant","It becomes extra training accuracy","To an external heat sink or a heat-reuse system"],"answer":2,"explanation":"Cooling transfers energy through the system. A complete explanation must identify the final heat destination."},"branch":"Thermal infrastructure","subbranch":"Facility heat rejection","science":[{"title":"Cooling energy boundary","equation":"COP = Q̇_removed / P_cooling; P_facility = P_IT + P_support","explanation":"A cooling system uses supporting power to transport heat. Measuring only the chip loop omits the pumps, fans, chillers, and other facility functions that may contribute to the complete system.","assumptions":"Steady accounting within an explicitly chosen boundary; COP is a cooling-performance ratio, while total facility accounting also includes non-cooling loads."}],"history":[],"prerequisites":["cdu"],"learningObjective":"Distinguish cooling-system COP from full-facility power accounting.","engineeringExample":"Synthetic plant removes 1 MW of heat with 0.2 MW of cooling electricity, so COP = 5. If IT load is 1 MW and other support uses 0.1 MW, facility input is 1 + 0.2 + 0.1 = 1.3 MW at that boundary; COP is not the facility/IT ratio.","evidenceNotes":"The example uses steady matched boundaries and invented loads. Heat-rejection method, environmental conditions and other support equipment affect actual power and water use; circulating water is not automatically consumed water.","labId":"library","scope":"No current calculator directly models this lesson’s main mechanism. Use the library for related bounds while retaining their stated omissions.","investigationId":"manufacturing","labScope":"No current calculator directly models this lesson’s main mechanism. Use the library for related bounds while retaining their stated omissions."}