How a Data Hall Moves Heat Outside

Every watt a data hall uses becomes heat, and all of it has to be moved outside. Here is how data center cooling really works: one watt followed through five handoffs, from the server fans to the hot aisle, a coil, chilled water, a chiller and a cooling tower or dry cooler, and the one wall that decides how well all of it works. On 19 July 2022 London reached 40.2 °C, and two chillers at a Google data center there failed. The fix was not more cooling: machines were switched off to make less heat. This video explains why. Chapters: 0:00 Two chillers, forty degrees 1:12 Five handoffs 2:19 The wall between the aisles 4:05 Air into water 5:05 Pushing heat uphill 6:24 The last handoff 8:09 The hot day 9:29 Where the heat could go Sources: Met Office, July heat review (2022): https://www.metoffice.gov.uk/about-us/news... Burt, S. (2025), Weather (RMetS), record UK temperatures of 19 July 2022: https://rmets.onlinelibrary.wiley.com/doi/... Google Cloud Service Health, incident fmEL9i2fArADKawkZAa2 (europe-west2, 19–20 July 2022): https://status.cloud.google.com/incidents/... Rasmussen, N., Calculating Total Cooling Requirements for Data Centers, APC/Schneider Electric White Paper 25: https://www.apc.com/us/en/support/resource... Uptime Institute, Global Data Center Survey 2025: https://datacenter.uptimeinstitute.com/rs/... ASHRAE TC 9.9, Thermal Guidelines for Data Processing Environments, 5th ed., reference card: https://www.ashrae.org/file%20library/tech... US DOE FEMP / LBNL, Best Practices Guide for Energy-Efficient Data Center Design (2024): https://www.energy.gov/sites/default/files... Engineering ToolBox, Air – Specific Heat: https://www.engineeringtoolbox.com/air-spe... Engineering ToolBox, Air – Density: https://www.engineeringtoolbox.com/air-den... US EPA WaterSense at Work, Section 6.3 Cooling Towers: https://www.epa.gov/system/files/documents... Engineering ToolBox, Water – Heat of Vaporization: https://www.engineeringtoolbox.com/water-p... Google Data Centers, Efficiency: https://www.google.com/about/datacenters/e... Google Data Centers, Hamina, Finland: https://datacenters.google/locations/hamin... DCD, Google's Finland data center pioneers new seawater cooling: https://www.datacenterdynamics.com/en/news... CapMan, Haminan Energia heat recovery facility (2026): https://capman.com/articles/capman-infras-... Footage via Wikimedia Commons (trimmed, colour-graded, labels and logos blurred): Lawrence Systems, "Data Center Tour & Technical Deep Dive into the Power, Data and Cooling Infrastructure!" and "What's Inside This Decommissioned Data Center?", CC BY 3.0 Jan Beránek, "Showers in natural draft cooling tower", CC BY-SA 4.0 Photos via Wikimedia Commons (cropped, slow zoom, labels and logos blurred): "Datacenter de ARSAT" by IMarcoHerrera, CC BY-SA 4.0; "Virginia Tech - data center" by Christopher Bowns, CC BY-SA 2.0; "Dry cooler LU-VE" by Nico aspe 22, CC BY-SA 4.0; "CERN Server 03" by Florian Hirzinger - www.fh-ap.com, CC BY-SA 3.0; "Chiller in a large commercial building, Brisbane" by Kgbo, CC BY-SA 4.0; "Centrale d'eau refroidie, Université Laval" by Rubisco4, CC BY-SA 3.0; "Lulea Facebook datacenter building" by Christopher Down, CC BY 4.0; "Hamina Orthodox Church 2023-01-21" by Niera, CC BY-SA 4.0 Licences: https://creativecommons.org/licenses/ (by/3.0, by/4.0, by-sa/2.0, by-sa/3.0, by-sa/4.0) Stock footage, Pexels License (pexels.com/video/ID): Carl UK (6814379); Eduardo Cano Photo Co. (5327934); MrColo (7140928); Edouard Matte (7796797); Andrey Kirievskiy (10008388); K (19582357); Andrei Ignia (4979299) Stock footage, Mixkit Free License (mixkit.co): 23282, 4380, 7892, 49185, 7866, 26856, 4362, 32523 AI footage note: 7 short atmosphere shots (rooftop heat haze, cold mist, a vapour plume, a cooling tower at sunset, a hot sky, a winter coast, a seabed cable) were generated with Google Flow (Veo). They set the mood only. No AI image is used for any mechanism, data plate, gauge or text. The cooling path itself is shown with real footage, real photos or our own diagrams. Music: original instrumental generated with ElevenLabs Music. Ambient sound: an ElevenLabs Sound Effects machine-hum loop plus synthesized airflow, wind and sea noise. Narration: synthetic voice (ElevenLabs) reading an original script.