{"api_version":"v1","schema_version":"1.1","dataset":"technologies","title":"Technology guides","generated":"2026-10-18","research_imported":"2026-10-18","licence":"Editorial summaries and structured fields by CoolPower Index. Reuse with attribution and a link. Source documents remain the property of their publishers.","coverage":"Published records only. Draft records, private booking data and contacts are never included. Capacity figures are tracked public coverage, not national totals.","schema":"https://coolpowerindex.com/data/v1/schema/","count":10,"records":[{"id":"800-vdc-power","type":"technology","status":"published","name":"800 VDC rack power","aliases":["800V DC","800 VDC","HVDC rack power","sidecar","solid-state transformer"],"summary":"800 VDC is a proposed power architecture for AI racks approaching 1 MW, converting AC to DC centrally and distributing 800 V DC to racks to cut copper, conversion stages and losses. NVIDIA has published the architecture and suppliers including ABB, Eaton and Schneider Electric have announced products, but it is not yet a shipping mainstream design.","maturity":"emerging","body_sections":[{"heading":"What it is","text":"Instead of many AC to DC conversions near each rack, power is converted at facility level and fed as 800 V DC to racks, then stepped down near the GPUs. NVIDIA says full-scale production of 800 VDC data centres will coincide with its Kyber rack systems in 2027, aimed at 1 MW IT racks. Interim designs use a rack-adjacent sidecar that converts AC to 800 VDC."},{"heading":"Supplier activity","text":"Schneider Electric announced an 800 VDC sidecar with NVIDIA. Eaton published an 800 VDC reference architecture and bought solid-state transformer maker Resilient Power Systems. ABB is co-developing with NVIDIA."},{"heading":"Prototype vs shipping","text":"Treat products as announced or development stage unless a supplier confirms orderable status and ratings. Standards, protection, arc flash practice and maintenance procedures for 800 VDC in white space are still maturing."},{"heading":"Sourcing considerations","text":"DC protection and fault clearing, personnel safety and training, connector standards, energy storage integration, and compatibility with existing AC UPS and switchgear."}],"rfi_questions":["Product status (prototype, announced, orderable, shipping)","Applicable safety standards and certification status","DC protection and arc flash approach","Interface with existing AC power train","Rack and connector compatibility with the chosen IT platform"],"category_ids":["ups-power","switchgear"],"supplier_ids":["schneider-electric","eaton","abb","nvent","delta-electronics"],"policy_ids":[],"project_ids":[],"sources":[{"url":"https://developer.nvidia.com/blog/nvidia-800-v-hvdc-architecture-will-power-the-next-generation-of-ai-factories/","title":"NVIDIA 800 VDC architecture will power the next generation of AI factories","publisher":"NVIDIA","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://developer.nvidia.com/blog/building-the-800-vdc-ecosystem-for-efficient-scalable-ai-factories/","title":"Building the 800 VDC ecosystem","publisher":"NVIDIA","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.se.com/ww/en/about-us/newsroom/news/press-releases/schneider-electric-highlights-innovation-in-800-vdc-power-systems-in-support-of-nvidia%E2%80%99s-next-generation-gpus-68ecb631098fd4ea49024353/","title":"Schneider Electric 800 VDC systems","publisher":"Schneider Electric","date_published":"2025-10","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.eaton.com/us/en-us/company/news-insights/news-releases/2025/eaton-unveils-next-generation-architecture.html","title":"Eaton 800 VDC architecture","publisher":"Eaton","date_published":"2025","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://new.abb.com/news/detail/129900/abb-to-develop-next-generation-ai-data-centers-with-nvidia","title":"ABB to develop next-generation AI data centers with NVIDIA","publisher":"ABB","date_published":"2025","date_accessed":"2026-10-18","authority_type":"company"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":"2025-10","effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/800-vdc-power/"},{"id":"backup-power-and-energy-storage","type":"technology","status":"published","name":"Backup power and energy storage","aliases":["UPS","static UPS","rotary UPS","DRUPS","generators","gensets","BESS","battery energy storage","flywheel"],"summary":"Backup power keeps IT running through grid faults: static UPS with batteries, rotary or flywheel UPS, diesel or gas generator sets, and increasingly battery energy storage that can also support the grid. Ratings mix kW, kVA and MWh, so power and energy must never be added together.","maturity":"established","body_sections":[{"heading":"What it is","text":"Static UPS (for example ABB MegaFlex DPA 1,000 to 2,000 kW) bridge the gap until generators start. Rotary and diesel rotary UPS (Piller UNIBLOCK up to 50 MW systems) combine flywheel and engine. Gensets (mtu 20V4000 DS4000 rated 3,950 to 4,000 kVA) carry longer outages. BESS store energy in MWh and deliver power in MW."},{"heading":"Units and roll-ups","text":"kVA is apparent power, kW real power, MWh energy. Genset ratings differ by duty (standby, prime, continuous, data centre continuous). Never sum MW with MWh, and never sum standby with continuous ratings."},{"heading":"Corporate status matters","text":"Check supplier health. Powin, a BESS integrator, filed for Chapter 11 in June 2025, its key assets went to FlexGen and its estate is in liquidation. Fleet support and warranty assignment should be confirmed in writing."},{"heading":"Sourcing considerations","text":"Emissions permits for gensets, fuel type (diesel, HVO, gas), start time, step load acceptance, battery chemistry and fire safety codes, runtime basis, and lifecycle service."}],"rfi_questions":["Rating basis (kW vs kVA, standby vs continuous)","Runtime and energy (MWh) at stated load","Start time and step load performance","Fuel, emissions limits and permits","Battery chemistry, fire testing and spacing","Warranty holder if the supplier is acquired or insolvent"],"category_ids":["ups-power","gensets","bess"],"supplier_ids":["abb","schneider-electric","eaton","piller-power-systems","socomec","mitsubishi-electric","huawei-digital-power","delta-electronics","rolls-royce-power-systems-mtu","cummins","caterpillar","kohler-energy-rehlko","ge-vernova","w-rtsil","powin"],"policy_ids":[],"project_ids":[],"sources":[{"url":"https://new.abb.com/news/detail/134362/abb-expands-megaflex-dpa-ups-range-for-next-gen-data-centers","title":"ABB MegaFlex DPA","publisher":"ABB","date_published":"2026-03-23","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.piller.com/product/uniblock-ups-from-150kw-up-to-50mw/","title":"Piller UNIBLOCK","publisher":"Piller","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.mtu-solutions.com/content/dam/mtu/products/power-generation/powergeneration-product-list-latest/32310781_PG_spec_20V4000DS4000_4000kVA_3D_FC_50Hz.pdf","title":"mtu 20V4000 DS4000","publisher":"Rolls-Royce Power Systems","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.flexgen.com/resources/blog/flexgen-completes-acquisition-powin-assets-expanding-global-leadership-grid-scale","title":"FlexGen completes acquisition of Powin assets","publisher":"FlexGen","date_published":"2025-08-19","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://powintrust.com/","title":"Powin Liquidating Trust","publisher":"Powin Liquidating Trust","date_published":null,"date_accessed":"2026-10-18","authority_type":"other"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":"2026-03-23","effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/backup-power-and-energy-storage/"},{"id":"brownfield-liquid-cooling-upgrades","type":"technology","status":"published","name":"Brownfield liquid cooling upgrades","aliases":["retrofit","rear door heat exchanger","RDHx","liquid-to-air CDU","hybrid cooling retrofit"],"summary":"Brownfield upgrades add liquid cooling to existing air cooled halls. Options run from rear-door heat exchangers and liquid-to-air CDUs that need no new facility water, to tapping chilled water with liquid-to-liquid CDUs, to full new warm water loops. Structural, power and water constraints decide what is feasible.","maturity":"established","body_sections":[{"heading":"Options","text":"Rear-door heat exchangers (for example Legrand ColdLogik) cool rack exhaust air with water. Liquid-to-air CDUs (Vertiv CoolChip CDU 70, Eaton RAA22 and RAA32, CoolIT AHx range) run direct-to-chip loops and reject heat to room air without facility water. Liquid-to-liquid CDUs can connect to existing chilled water but may be limited by its temperature and capacity."},{"heading":"Constraints","text":"Floor loading, ceiling height for pipework, existing chilled water temperature and spare capacity, electrical capacity per rack, and leak risk over live equipment. Air handling still has to remove residual heat."},{"heading":"Sourcing considerations","text":"Ask for a site survey, phasing plan with live operations, flushing and commissioning method, and how capacity is rated at your existing water temperatures. Munters and others market air-to-liquid upgrade paths."}],"rfi_questions":["Existing chilled water temperature and spare capacity","Whether a liquid-to-air CDU or RDHx avoids new pipework","Floor loading and pipe routing","Live-site installation method and risk controls","Residual air cooling load after retrofit"],"category_ids":["cooling-cdu","chillers"],"supplier_ids":["legrand","vertiv","eaton","boyd","coolit-systems","munters","stulz","rittal"],"policy_ids":[],"project_ids":[],"sources":[{"url":"https://www.legrand.com/datacenter/int-en/white-space/cooling/usystems-rear-door-cooling/cl20-proactiverdc","title":"CL20 ProActiveRDC","publisher":"Legrand","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.vertiv.com/en-us/products-catalog/thermal-management/high-density-solutions/vertiv-coolchip-cdu/","title":"Vertiv CoolChip CDU","publisher":"Vertiv","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.eaton.com/us/en-us/catalog/thermal-management-solutions/coolant-distribution-unit-cdu.html","title":"Eaton CDU (liquid-to-air section)","publisher":"Eaton","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.coolitsystems.com/cdu-product/chx2000/","title":"CoolIT CHx2000 FAQ (AHx liquid-to-air)","publisher":"CoolIT Systems","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://datacenter.munters.com/products/cdu-data-center/","title":"Munters CDU (upgrade path)","publisher":"Munters","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":null,"effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/brownfield-liquid-cooling-upgrades/"},{"id":"coolant-distribution-units","type":"technology","status":"published","name":"Coolant distribution units (CDUs)","aliases":["CDU","CDUs","coolant distribution unit","cooling distribution unit","FDU","facility distribution unit","TCS","technology cooling system"],"summary":"A CDU is the pump, heat exchanger and control skid that separates the facility water loop from the clean technology cooling system (TCS) loop feeding cold plates or immersion tanks. Ratings depend on approach temperature, flow and fluid, so capacities are only comparable at stated conditions.","maturity":"established","body_sections":[{"heading":"What it is","text":"A CDU moves heat from the IT-side loop (TCS) to the facility water system (FWS) through a plate heat exchanger. It controls supply temperature and flow, keeps the TCS above the dew point, filters the coolant and raises alarms on leaks, pressure or flow. Liquid-to-air units reject heat to room air instead and suit sites without facility water."},{"heading":"Form factors","text":"In-rack units sit inside an IT rack and typically cover tens to low hundreds of kW. In-row units sit in the row and in 2026 commonly span about 0.6 to 2.5 MW. Facility or skid units sit in a gallery or plant room and are marketed from about 2.5 MW to beyond 8 MW per unit. Examples with published figures: Vertiv CoolChip CDU 70 to 2300 kW, Rittal CDU In-Row 1,000 kW at 4 K approach, DCX 8 MW FDU at 2 °C approach."},{"heading":"Why ratings are hard to compare","text":"A capacity figure means little without approach temperature difference (ATD), flow per kW, fluid (water, PG25) and supply temperatures. The same Eaton ROL2300 is rated 2,300 kW at 8 °C approach and 1,150 kW at 4 °C. LiquidStack's CDU-1MW reaches 1,350 kW at 1.15 lpm/kW but 1,004 kW at 1.50 lpm/kW. Always normalise to the same ATD and lpm/kW."},{"heading":"Sourcing considerations","text":"Check redundancy (N+1 pumps, 2N filters, dual power feeds), filtration grade (25 or 50 micron, side-stream 0.2 micron options), wetted materials and fluid compatibility, controls protocols (Redfish, Modbus, BACnet, SNMP), group control for many units, harmonics of pump drives, service access, factory test load, local service coverage and lead time. The Open Compute Project publishes the Project Deschutes facility specification as an open reference for CDU requirements."},{"heading":"Prototype vs shipping","text":"Many 2025 to 2026 CDUs are announced before they ship. Examples in our records: Trane LiquidStack CDU 2.X is on pre-order with shipments from Q2 2027. nVent lists CX121 and CZ61/CZ62 on a 'coming in 2026' page. Supplier records mark each product family as prototype, announced, orderable or shipping, and unknown status stays unknown."}],"rfi_questions":["State capacity at a defined ATD, TCS flow per kW, fluid and FWS/TCS supply temperatures","Pump redundancy and whether pumps and filters are hot-swappable","Filtration grade on TCS and FWS sides","Wetted materials list and approved coolants","Control protocols and group control limits","Electrical supply options, dual feed, harmonic mitigation","Factory acceptance test load and witness options","Commissioning, flushing and fluid sampling responsibility","Local service presence and spares stock in the project country","Lead time and current shipping status"],"category_ids":["cooling-cdu"],"supplier_ids":["vertiv","motivair-by-schneider-electric","schneider-electric","stulz","nvent","coolit-systems","boyd","eaton","rittal","liquidstack","trane","carrier","johnson-controls-york","daikin-applied","chilldyne","munters","delta-electronics","mitsubishi-electric-hydronics-it-cooling","airedale-by-modine","nortek-data-center-cooling","envicool","kelvion","dcx-liquid-cooling-systems","jetcool","zutacore","accelsius"],"policy_ids":[],"project_ids":[],"sources":[{"url":"https://www.opencompute.org/documents/ocp-specification-deschutes-final-2025-09-05-pdf","title":"Project Deschutes: data center facilities specification","publisher":"Open Compute Project","date_published":"2025-09-05","date_accessed":"2026-10-18","authority_type":"standards-body"},{"url":"https://www.vertiv.com/en-us/products-catalog/thermal-management/high-density-solutions/vertiv-coolchip-cdu/","title":"Vertiv CoolChip CDU 70-2300 kW","publisher":"Vertiv","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.eaton.com/us/en-us/catalog/thermal-management-solutions/coolant-distribution-unit-cdu.html","title":"Coolant distribution unit (CDU)","publisher":"Eaton","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.rittal.com/com-en/products/PG20231215KLI101/PG20231245KLI1005/PG20240116KLI207/PRO136623?variantId=3343200","title":"Rittal CDU In-Row 3343200","publisher":"Rittal","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.dcx.eu/product/fdu-8mw","title":"DCX 8 MW FDU","publisher":"DCX","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://elibrary.tranetechnologies.com/public/commercial-hvac/Literature/Sales/CDU-SLB001-EN_04202026.pdf","title":"LiquidStack CDU-1MW sales literature","publisher":"Trane Technologies","date_published":"2026-04-20","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.trane.com/commercial/north-america/us/en/about-us/newsroom/press-releases/liquidstack-cdu-2x.html","title":"Trane launches LiquidStack CDU 2.X","publisher":"Trane Technologies","date_published":"2026-09-29","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.nvent.com/en-us/data-solutions/next-generation-liquid-cooling-and-power-portfolios-coming-2026","title":"nVent next generation liquid cooling","publisher":"nVent","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":"2026-09-29","effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/coolant-distribution-units/"},{"id":"heat-reuse","type":"technology","status":"published","name":"Data centre heat reuse","aliases":["waste heat recovery","district heating","ERF","energy reuse factor","heat export"],"summary":"Heat reuse exports data centre heat to district heating, buildings or industry, usually via plate heat exchangers and often heat pumps. Liquid cooling raises the heat grade. In Germany EnEfG section 11 sets energy reuse factor requirements for new data centres, so heat reuse is becoming a design and permitting question.","maturity":"mixed","body_sections":[{"heading":"What it is","text":"Warm facility water passes through a plate heat exchanger to a heat network. Where the network needs higher temperatures, heat pumps lift the temperature at an electricity cost."},{"heading":"Example","text":"Alfa Laval describes HeatChain in Finland using AlfaQ plate heat exchangers in modular data boiler sites that feed district heating, with the company reporting 50 GWh of heat delivered in 2025. That is a company claim for a specific scheme, not a general benchmark."},{"heading":"Policy link","text":"Germany's EnEfG section 11 sets energy reuse factor targets for new data centres by commissioning date (see policy record de-enefg-section-11-data-centres). EU data centre reporting under the EED includes reuse indicators (eu-eed-data-centre-reporting). Check current text and dates in those records."},{"heading":"Sourcing considerations","text":"Heat offtake contracts, offtaker demand profile, temperature and reliability obligations, metering boundary for ERF, heat pump ownership, and what happens when the offtaker does not take heat."}],"rfi_questions":["Offtaker identity, temperature and seasonal demand","ERF metering boundary and calculation method","Heat pump need and who pays its electricity","Backup heat rejection when offtake stops","Contract term and liability"],"category_ids":["heat-rejection"],"supplier_ids":["alfa-laval","kelvion","submer","dcx-liquid-cooling-systems","mitsubishi-electric-hydronics-it-cooling","stulz"],"policy_ids":["de-enefg-section-11-data-centres","eu-eed-data-centre-reporting","de-enefg-amendment-2026"],"project_ids":[],"sources":[{"url":"https://www.alfalaval.com/media/stories/data-center-cooling/heatchain-data-boiler/","title":"AlfaQ heat exchangers and district heating (HeatChain)","publisher":"Alfa Laval","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.gesetze-im-internet.de/enefg/__11.html","title":"EnEfG section 11","publisher":"Bundesministerium der Justiz","date_published":null,"date_accessed":"2026-10-18","authority_type":"legislation"},{"url":"https://energy.ec.europa.eu/topics/energy-efficiency/energy-efficiency-targets-directive-and-rules/energy-efficiency-directive/energy-performance-data-centres_en","title":"Energy performance of data centres","publisher":"European Commission","date_published":null,"date_accessed":"2026-10-18","authority_type":"government"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":null,"effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/heat-reuse/"},{"id":"power-distribution","type":"technology","status":"published","name":"Data centre power distribution","aliases":["MV switchgear","LV switchboards","busway","busduct","PDU","transformers","power train"],"summary":"Power distribution covers the chain from the utility or on-site connection through MV switchgear and transformers to LV switchboards, UPS, busway and rack PDUs. AI loads push higher currents and faster build schedules, so lead times for transformers and switchgear and factory capacity are central sourcing risks.","maturity":"established","body_sections":[{"heading":"What it is","text":"Medium voltage switchgear and transformers step down utility power. LV switchboards and UPS feed busway or cable to rack PDUs. Prefabricated power skids and modular enclosures shorten site work."},{"heading":"Market signals","text":"Suppliers are adding capacity: Hitachi Energy announced a 528 million USD transformer plant in Mississippi (Sept 2026). Siemens announced more than 200 million USD for US switchgear factories. Legrand bought Kratos Industries (LV/MV equipment) and nVent bought Maverick Power. These are capacity signals, not delivery guarantees."},{"heading":"Sourcing considerations","text":"Confirm lead times by item, factory location, type tests to IEC or UL as required in the project country, fault levels, harmonic limits, and the interface to UPS and future 800 VDC equipment."}],"rfi_questions":["Lead time for transformers and MV switchgear by factory","Applicable standards (IEC vs UL) for the project country","Fault level and selectivity study ownership","Prefabrication scope and site testing","Spare parts and service response time"],"category_ids":["switchgear","ups-power"],"supplier_ids":["siemens","hitachi-energy","ge-vernova","ls-electric","schneider-electric","eaton","abb","legrand","nvent","socomec"],"policy_ids":["gb-ofgem-data-centre-connection-reforms-curate","ie-cru-large-energy-users-connection-policy-2025"],"project_ids":[],"sources":[{"url":"https://www.hitachienergy.com/news-and-events/press-releases/2026/09/hitachi-deepens-commitment-to-u-s-manufacturing-with-528-million-mississippi-transformer-factory","title":"Hitachi 528 million USD Mississippi transformer factory","publisher":"Hitachi Energy","date_published":"2026-09-15","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://press.siemens.com/global/en/pressrelease/siemens-strengthens-ai-infrastructure-leadership-more-200-million-us-manufacturing","title":"Siemens US manufacturing investments","publisher":"Siemens","date_published":"2026","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.legrand.us/about-us/newsroom/press/legrand-acquires-kratos-industries","title":"Legrand acquires Kratos Industries","publisher":"Legrand","date_published":"2026-02-12","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://investors.nvent.com/press-releases/press-release-details/2026/nVent-Completes-Acquisition-of-Maverick-Power/default.aspx","title":"nVent completes acquisition of Maverick Power","publisher":"nVent","date_published":"2026-10-01","date_accessed":"2026-10-18","authority_type":"company"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":"2026-10-01","effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/power-distribution/"},{"id":"direct-liquid-cooling","type":"technology","status":"published","name":"Direct liquid cooling (direct-to-chip)","aliases":["DLC","direct-to-chip","D2C","cold plate cooling","two-phase direct-to-chip"],"summary":"Direct liquid cooling pumps coolant through cold plates mounted on CPUs, GPUs and other hot components, removing most server heat into liquid. It is the main route to rack densities beyond what air can handle, and it comes in single-phase water or glycol and two-phase refrigerant variants.","maturity":"established","body_sections":[{"heading":"What it is","text":"Cold plates sit on the hottest chips and a closed technology cooling loop carries the heat to a CDU. Remaining components still need some air cooling, so most halls are hybrid. Single-phase systems use treated water or water-glycol (often PG25). Two-phase systems (for example Accelsius NeuCool, ZutaCore HyperCool) boil a dielectric refrigerant at the cold plate and avoid water in the white space."},{"heading":"Where it fits","text":"New AI halls and retrofits where rack density outgrows air. Vendors such as LiquidStack note that air cooling struggles beyond roughly 30 to 50 kW per rack. Treat such thresholds as vendor guidance, not a standard."},{"heading":"Sourcing considerations","text":"The system crosses supplier boundaries: server OEM cold plates, rack manifolds, quick disconnects (for example UQD and MQD/MQDB couplings), CDU, and facility water. Agree who owns fluid quality, flushing, leak detection and warranty at each interface. Ask for wetted materials lists and coolant qualification. Negative pressure systems (Chilldyne) trade pump design for reduced leak risk."},{"heading":"Prototype vs shipping","text":"Single-phase DLC with CDUs is commercially shipping from many vendors. Two-phase systems are shipping from some specialists (Accelsius MR250 is listed as a product) but have a smaller installed base. Treat new cold plate and connector standards (OCP MQD/MQDB specification approved Oct 2026) as emerging."}],"rfi_questions":["Which party supplies and warrants cold plates, manifolds, quick disconnects and CDU","Approved coolant and fluid maintenance plan","Leak detection method and response","Facility water temperature class needed (ASHRAE W class)","Share of heat captured by liquid vs residual air","For two-phase: refrigerant type, GWP, regulatory status and refill logistics"],"category_ids":["cooling-cdu"],"supplier_ids":["coolit-systems","boyd","eaton","vertiv","jetcool","zutacore","accelsius","chilldyne","danfoss","nvent","motivair-by-schneider-electric","legrand","johnson-controls-york","rittal"],"policy_ids":[],"project_ids":[],"sources":[{"url":"https://www.ashrae.org/file%20library/technical%20resources/bookstore/emergence-and-expansion-of-liquid-cooling-in-mainstream-data-centers_wp.pdf","title":"Emergence and expansion of liquid cooling in mainstream data centers","publisher":"ASHRAE TC 9.9","date_published":null,"date_accessed":"2026-10-18","authority_type":"standards-body"},{"url":"https://www.ashrae.org/File%20Library/Technical%20Resources/Bookstore/WhitePaper_TC099-WaterCooledServers.pdf","title":"Water-cooled servers: common designs, components and processes","publisher":"ASHRAE TC 9.9","date_published":null,"date_accessed":"2026-10-18","authority_type":"standards-body"},{"url":"https://www.opencompute.org/wp-content/uploads/2026/10/MQD-MQDB-OCP-Design-Specification-1.0.0.pdf","title":"MQD/MQDB OCP design specification 1.0.0","publisher":"Open Compute Project","date_published":"2026-10","date_accessed":"2026-10-18","authority_type":"standards-body"},{"url":"https://accelsius.com/single-product-mr250/","title":"NeuCool MR250","publisher":"Accelsius","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://zutacore.com/solutions","title":"HyperCool","publisher":"ZutaCore","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://assets.danfoss.com/documents/latest/606093/AM521139373386en-000701.pdf","title":"Danfoss Hansen MQD/MQDB data sheet","publisher":"Danfoss","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://liquidstack.com/cdu-direct-to-chip/coolant-distribution-unit-1-megawatt","title":"CDU-1MW (air vs liquid FAQ)","publisher":"LiquidStack","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":"2026-10","effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/direct-liquid-cooling/"},{"id":"heat-rejection","type":"technology","status":"published","name":"Heat rejection","aliases":["dry coolers","adiabatic coolers","cooling towers","evaporative cooling","free cooling","chillers"],"summary":"Heat rejection is the plant that finally dumps data centre heat to outdoor air or water: dry coolers, adiabatic coolers, cooling towers, evaporative systems and chillers. Liquid cooling with warm water lets more hours run on dry or adiabatic coolers without compressors, trading footprint and water use against energy.","maturity":"established","body_sections":[{"heading":"What it is","text":"Dry coolers pass facility water through finned coils with fans. Adiabatic units pre-cool air with water sprays or pads on hot days. Evaporative towers use water evaporation and need water treatment. Chillers add compressors when outdoor conditions or required temperatures demand it."},{"heading":"How to compare","text":"Ask for the ambient rating point, fluid in and out temperatures, fan power, sound basis and distance, footprint, and annual water use at the site climate. Kelvion's V-shape dry cooler range, for example, is stated at 25 °C ambient with 40 °C in and 35 °C out. Figures at other rating points are not comparable."},{"heading":"Sourcing considerations","text":"Water availability and permits, noise limits, plume and legionella control, refrigerant choice for chillers, and controls integration with CDUs. Recent consolidation matters: Vertiv bought ThermoKey (dry coolers) in June 2026."},{"heading":"Prototype vs shipping","text":"Mature and shipping. Newer hybrid plant packages (for example Nortek StatePoint) are also marketed. Check reference sites at similar climate."}],"rfi_questions":["Rating ambient and fluid temperatures","Fan power at design and part load","Water use per year at the site, and water quality needs","Sound power and sound pressure at a stated distance","Footprint and weight","Free cooling hours assumed and climate data source"],"category_ids":["heat-rejection","chillers"],"supplier_ids":["kelvion","alfa-laval","munters","vertiv","nortek-data-center-cooling","ecocooling","carrier","trane","johnson-controls-york","daikin-applied","airedale-by-modine","mitsubishi-electric-hydronics-it-cooling","modine"],"policy_ids":[],"project_ids":[],"sources":[{"url":"https://d2xjeen3zaup4u.cloudfront.net/asset/767398133948/document_7i1fi0k3uh1ldfq08sm75jqk5l/PF_HRR_DryCooler_VShape_Range_EN.pdf","title":"V-shape dry cooler range","publisher":"Kelvion","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://datacenter.munters.com/products/cdu-data-center/","title":"Munters data center cooling portfolio","publisher":"Munters","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.vertiv.com/en-us/about/news-and-events/corporate-news/2026/vertiv-completes-acquisition-of-thermokey-expanding-heat-rejection-portfolio-for-ai-data-centers/","title":"Vertiv completes ThermoKey acquisition","publisher":"Vertiv","date_published":"2026-06-12","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.prnewswire.com/news-releases/nortek-dcc-unveils-c-force-lifecycle-model-and-statepoint-2025-hybrid-cooling-to-deliver-efficiency-sustainability-and-performance-302449478.html","title":"Nortek StatePoint 2025","publisher":"Nortek DCC","date_published":"2025","date_accessed":"2026-10-18","authority_type":"company"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":"2026-06-12","effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/heat-rejection/"},{"id":"immersion-cooling","type":"technology","status":"published","name":"Immersion cooling","aliases":["single-phase immersion","two-phase immersion","tank immersion","precision immersion","chassis immersion"],"summary":"Immersion cooling submerges servers in a dielectric fluid, either in open tanks (single-phase or two-phase) or in sealed chassis (precision immersion). It removes heat from all components, allows warm water heat rejection and can eliminate server fans, but needs adapted hardware, fluid management and service procedures.","maturity":"mixed","body_sections":[{"heading":"What it is","text":"In single-phase tanks the fluid stays liquid and a CDU or heat exchanger moves heat to facility water. Two-phase systems boil a fluid at the components and condense it above the bath. Precision or chassis immersion (Iceotope) seals fluid inside each server chassis."},{"heading":"Published examples","text":"Submer SmartPod EXO lists up to 361 kW heat dissipation depending on model and conditions and operation with water up to 60 °C. GRC's ICEraQ Series 10 launch (2021) quoted 200 kW with warm water and 368 kW with chilled water."},{"heading":"Sourcing considerations","text":"Ask about fluid type, supply chain, toxicity and end-of-life handling, server and warranty compatibility, floor loading, service lifting, fluid loss rates and fire classification. Confirm whether the tank CDU is redundant (Submer TwinTank uses 2N CDUs)."},{"heading":"Prototype vs shipping","text":"Single-phase tank immersion is commercially shipping from several suppliers. Some vendors' current product lines were not verified in this run and stay as drafts. Two-phase immersion has faced fluid regulatory pressure and should be checked case by case."}],"rfi_questions":["Fluid chemistry, supplier and replacement cost","Server OEM warranty position","Tank weight and floor loading","Redundancy of pumps or CDUs","Water temperature range and heat reuse potential","Maintenance procedure and lifting equipment"],"category_ids":["immersion"],"supplier_ids":["submer","green-revolution-cooling-grc","iceotope","asperitas","liquidstack","stulz","alfa-laval"],"policy_ids":[],"project_ids":[],"sources":[{"url":"https://submer.com/smartpod/exo/","title":"SmartPod EXO","publisher":"Submer","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.grcooling.com/press_releases/grc-releases-the-next-generation-of-data-center-liquid-immersion-cooling/","title":"GRC releases ICEraQ Series 10","publisher":"GRC","date_published":"2021-05-18","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.iceotope.com/solutions/iceotope-servers/kul-ai-solutions-and-technical-specifications/","title":"KUL AI solutions","publisher":"Iceotope","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.stulz.com/products/detail/cybercool-cdu/","title":"CyberCool CDU (for DLC and immersion)","publisher":"STULZ","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":"2021-05-18","effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/immersion-cooling/"},{"id":"warm-water-cooling-loops","type":"technology","status":"published","name":"Warm-water cooling loops","aliases":["warm water cooling","W32","W40","W45","W+","ASHRAE W classes","high temperature facility water"],"summary":"Warm-water loops run facility water at 30 to 45 °C or more so that heat can be rejected with dry coolers for most of the year and reused more easily. ASHRAE TC 9.9 defines W classes by maximum facility water supply temperature, from W17 up to W45 and W+ above 45 °C.","maturity":"established","body_sections":[{"heading":"What it is","text":"Liquid cooled chips tolerate much warmer coolant than air cooled rooms need. Raising facility water temperature cuts or removes chiller hours and raises the grade of recovered heat."},{"heading":"ASHRAE classes","text":"ASHRAE TC 9.9 uses classes W17, W27, W32, W40, W45 and W+, each named after the maximum facility water supply temperature in °C. Equipment claiming a class should run unthrottled across that range. Use the class to align IT, CDU and plant designs."},{"heading":"Examples","text":"STULZ rates its CyberCool CDU at 32 °C facility water and 36 °C TCS supply. Trane's LiquidStack CDU 2.X supports facility inlet up to 45 °C. DCX designs its 8 MW FDU for 45 °C warm water operation."},{"heading":"Sourcing considerations","text":"Warmer water needs a smaller CDU approach temperature to keep chips within limits, which means larger heat exchangers. Confirm the IT vendor's allowed TCS temperature, and agree who carries the risk if a future GPU generation needs colder water."}],"rfi_questions":["Target ASHRAE W class and why","Approach temperature the CDU must achieve at that class","IT vendor maximum TCS supply temperature","Chiller backup hours and trim strategy","Heat reuse offtake temperature"],"category_ids":["cooling-cdu","heat-rejection"],"supplier_ids":["stulz","liquidstack","trane","dcx-liquid-cooling-systems","coolit-systems","submer","kelvion","carrier"],"policy_ids":["de-enefg-section-11-data-centres"],"project_ids":[],"sources":[{"url":"https://www.ashrae.org/file%20library/technical%20resources/bookstore/emergence-and-expansion-of-liquid-cooling-in-mainstream-data-centers_wp.pdf","title":"Emergence and expansion of liquid cooling in mainstream data centers","publisher":"ASHRAE TC 9.9","date_published":null,"date_accessed":"2026-10-18","authority_type":"standards-body"},{"url":"https://www.ashrae.org/file%20library/technical%20resources/bookstore/supplemental%20files/therm-gdlns-5th-r-e-refcard.pdf","title":"Thermal Guidelines 5th edition reference card","publisher":"ASHRAE","date_published":null,"date_accessed":"2026-10-18","authority_type":"standards-body"},{"url":"https://www.stulz.com/products/detail/cybercool-cdu/","title":"CyberCool CDU","publisher":"STULZ","date_published":null,"date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.trane.com/commercial/north-america/us/en/about-us/newsroom/press-releases/liquidstack-cdu-2x.html","title":"LiquidStack CDU 2.X","publisher":"Trane Technologies","date_published":"2026-09-29","date_accessed":"2026-10-18","authority_type":"company"},{"url":"https://www.dcx.eu/blog/dcx-announces-new-8mw-coolant-distribution-unit","title":"DCX announces new 8MW CDU","publisher":"DCX","date_published":"2026","date_accessed":"2026-10-18","authority_type":"company"}],"last_checked":"2026-10-18","reviewer":"CoolPower Index research (automated, sourced)","dates":{"published":"2026-09-29","effective":null,"event":null,"expected_operation":null,"last_checked":"2026-10-18","next_review":"2027-04-18","review_cadence_days":182},"url":"https://coolpowerindex.com/technology/warm-water-cooling-loops/"}]}