--- title: Data center cooling, explained simply url: https://7hive.com/cooling canonical: https://7hive.com/cooling updated: 2026-10-06 author: 7Hive LLC description: Plain-language guide to data center cooling cost. Air, direct-to-chip liquid, and immersion compared on upfront cost, monthly power, and water. --- # Data center cooling, explained simply Cooling carries the heat out. You pay once to build it, then every month in power, and sometimes in water. Updated 6 October 2026. Written by 7Hive LLC. Human page: https://7hive.com/cooling The cheap build and the cheap month are often different machines. Ranges are directional. Ask a vendor before a number goes into a model. ## Ten-second cheat sheet Upfront is the build. The monthly bill is mostly electricity. Dense AI means racks from about 40 kW up, including a GB200-class rack near 120 kW. | Setup | Upfront | Bill each month | Water | Fits dense AI? | | --- | --- | --- | --- | --- | | Air | Lowest | Highest power | Medium to high if the tower is wet | No | | Liquid, closed loop, dry coolers | Medium to high | Lower power | Very low | Yes | | Liquid plus evaporative | Medium | Lower power | High | Yes | | Immersion, dry rejection | Highest | Often the lowest power | Very low | Yes | ## Three builds ### Air Fans push room air through the servers. A wet tower can dump the heat outside. Cheapest install at normal density, highest power bill. Often about $2 to $4 million per MW. Water is high if the tower is wet. ### Direct-to-chip liquid A plate on the chip, a CDU between loops, then dry coolers or a tower. Often about $3 to $6 million per MW, about 1.5 to 2 times the air kit. The CDU box alone is often cited at $0.10 to $0.20 per watt. Lower power than air. Almost no water if the outdoor cooler is dry. Outdoor fans can still be a serious power cost when the air outside is already hot. ### Immersion The server sits in a tank of fluid that does not conduct electricity. Heat still leaves through an outdoor cooler. Usually the highest install, because of the tanks, the fluid, and the servers built for the bath. Often the lowest cooling power. Almost no water if rejection is dry. Where power is expensive, that monthly saving is how the higher build cost pays itself back. ## When air stops Under about 15 to 20 kW per rack, air is enough and it is the cheapest. From 30 to 40 kW it is a stretch. A GB200-class rack near 120 kW ships with cold plates, so liquid is already required. NVIDIA’s DGX GB200 user guide puts rack power at about 120 kW. Schneider’s liquid infrastructure is cited up to 132 kW per rack. ## Where the heat goes The chip loop and the outdoor loop are different choices. Dry coolers use more metal and more fan power on a hot afternoon, almost no water, and less salt on the metal. Wet towers use less electricity on hot days, spend water, and corrode if the coast is salty. WUE is site water divided by IT energy, in liters per kWh. Brazil’s Redata benefit, Lei 15.504 of 2026, asks for 0.05 L/kWh or less, measured yearly. A dry cooler can meet that. A wet tower spends the water the statute counts. Luís Tossi, of the Brazilian data center association, told Neo Mondo that closed-loop condensers meet the index by using more electricity and skipping a constant water refill. ## How the studies drew the box Each study measures a different box. Read them as separate scopes. - Schneider WP282, a whole 2 MW building in 2019. At 10 kW per rack, air and immersion were about $7.02 and $6.98 per watt. At 40 kW, immersion was about $6.02, mostly because the building got smaller. https://blog.se.com/datacenter/architecture/2020/02/24/liquid-vs-air-cooling-which-is-the-capex-winner/ - Data Center Scope reads Turner & Townsend 2025 to 2026 as a 7 to 10 percent construction premium for a liquid hall, and cites Uptime for a 5 to 10 percent direct-liquid add. https://datacenterscope.com/cooling/data-center-cooling-cost/ - Adam Silva, 16 racks, 2026: advanced air about $1,800 to $3,200 per kW, direct-to-chip $3,500 to $5,000, single-phase immersion $4,300 to $6,500. https://www.adamsilvaconsulting.com/insights/data-center-cooling-economics-2026 - A secondary summary of IDTechEx, December 2025, put one GB200-class rack’s cooling hardware near $55,000, of which the CDU was near $23,000. https://www.aitooldiscovery.com/ai-infra/data-center-cooling-explained - TechTarget on Schneider WP220: liquid supply from 32°C to 45°C cut water about 66 percent in a Dallas case and about 82 percent in Paris. PUE moved under 1 percent. https://www.techtarget.com/it-infrastructure/news/366651212/AI-data-centers-can-run-hot-to-stay-cool-report and https://www.se.com/ww/en/download/document/SPD_WP220_EN/ - Uptime, April 2026: a dry cooler can match evaporative PUE in many climates. Evaporative PUE is bought with water. https://intelligence.uptimeinstitute.com/resource/dry-cooling-energy-performance-can-rival-evaporative-cooling - Field notes, not cost sources. @omijagun on 5 October 2026 put GB200 racks up to about 140 kW against halls built for 10 to 15 kW. https://x.com/omijagun/status/2107123657575194952 @AliLenjani a day earlier pointed at galvanic corrosion in the CDU and the cold plates. https://x.com/AliLenjani/status/2106805745853567451 ## Names on the package Full list: https://7hive.com/glossary#players Cold plates and CDUs: CoolIT, Motivair, nVent, Boyd, Asetek, Vertiv, and Schneider. Outdoor coolers: Munters, STULZ, Vertiv, and Schneider. Immersion tanks: GRC, Submer, and LiquidStack. ## Common questions ### What does data center cooling do? It carries heat out of the building. Almost every watt the chips use becomes a watt of heat. Cooling is the fans, cold plates, tanks, pumps, and outdoor boxes that move that heat outside. ### How much does data center cooling cost to build? As a planning range, air cooling is often about $2 to $4 million per megawatt of IT. Direct-to-chip liquid is often about $3 to $6 million per megawatt, or about 1.5 to 2 times the air cooling kit. Immersion usually costs more to install than cold plates. These are directional ranges, not a bid. ### When is air cooling enough for a data center? Below about 15 to 20 kW per rack, air is usually enough and it is the cheapest install. Above about 30 to 40 kW per rack, air cannot carry the heat. Current AI racks, including NVIDIA GB200-class racks around 120 kW, are built for liquid cooling. ### Does liquid cooling use water? The loop on the chip can be closed, so it does not consume water. Water use depends on how you reject the heat outside. Dry coolers use almost none. Evaporative towers and adiabatic assist use water on purpose, to cut electricity on hot days. ### What is a CDU? A coolant distribution unit. It sits between the cold plates and the building loop, moves heat off the rack, and keeps the IT fluid separate from the outdoor loop. The box alone is often cited around $0.10 to $0.20 per watt, before pipe, coolers, and install. ### What is the difference between cold plates and immersion? A cold plate bolts liquid onto the hottest chips. Immersion puts the whole server in a tank of fluid that does not conduct electricity. Cold plates are the common path for current AI racks. Immersion usually costs more to install and often uses less electricity to run. ### What cooling choice matters for a dense AI hall? Liquid is already required, so the useful comparison is closed-loop dry coolers against evaporative heat rejection, and cold plates against immersion. Dry costs more in fans or metal and uses very little water. Evaporative saves electricity on hot days and spends water. ## Sources Checked 6 October 2026. - NVIDIA DGX GB200 user guide, hardware. https://docs.nvidia.com/dgx/dgxgb200-user-guide/hardware.html - NVIDIA, GB200 NVL72. https://www.nvidia.com/en-us/data-center/gb200-nvl72/ - NVIDIA, GB200 NVL72 designs contributed to the Open Compute Project. https://developer.nvidia.com/blog/nvidia-contributes-nvidia-gb200-nvl72-designs-to-open-compute-project/ - NVIDIA blog, Blackwell platform water efficiency. https://blogs.nvidia.com/blog/blackwell-platform-water-efficiency-liquid-cooling-data-centers-ai-factories/ - Schneider Electric white paper 282, 2020 summary. https://blog.se.com/datacenter/architecture/2020/02/24/liquid-vs-air-cooling-which-is-the-capex-winner/ - Schneider Electric white paper 220. https://www.se.com/ww/en/download/document/SPD_WP220_EN/ - TechTarget, on the Schneider 32°C to 45°C comparison. https://www.techtarget.com/it-infrastructure/news/366651212/AI-data-centers-can-run-hot-to-stay-cool-report - Uptime Intelligence, dry cooling can rival evaporative cooling. https://intelligence.uptimeinstitute.com/resource/dry-cooling-energy-performance-can-rival-evaporative-cooling - Data Center Scope, cooling cost breakdown. https://datacenterscope.com/cooling/data-center-cooling-cost/ - Adam Silva Consulting, cooling economics 2026. https://www.adamsilvaconsulting.com/insights/data-center-cooling-economics-2026 - IDTechEx rack cooling hardware, as summarized by AI Tool Discovery. https://www.aitooldiscovery.com/ai-infra/data-center-cooling-explained - Brazil, Lei 11.196 of 2005 as amended by Lei 15.504 of 2026. https://www.planalto.gov.br/ccivil_03/_Ato2004-2006/2005/Lei/L11196compilado.htm - Senate of Brazil, Redata signed into law. https://www12.senado.leg.br/noticias/materias/2026/09/16/sancionada-lei-de-incentivo-para-a-instalacao-de-data-centers - Neo Mondo, on the Redata water index. https://neomondo.org.br/energia/o-brasil-fixou-em-005-litro-por-kwh-a-regua-hidrica-dos-data-centers-e-ela-mede-pouco-mais-da-metade-da-conta - Field note on X, rack density, 5 October 2026. https://x.com/omijagun/status/2107123657575194952 - Field note on X, plumbing and corrosion, 4 October 2026. https://x.com/AliLenjani/status/2106805745853567451