Scientific papers

Research paperFree to readEditor’s pick

Journal of Science Policy & Governance (Journal of Science Policy and Governance, Inc.) · 2026

Is Power Usage Effectiveness (PUE) Still Fit for Purpose? An Integrative Review of Data Center Metrics for Assessing the Environmental Impact of Modern AI Infrastructure

Give the sustainability panel at least four axes (PUE, CUE, WUE/WUEsource and a placeholder for IT productivity) and show them as a radar chart, so a low PUE never appears alone.

• Water-energy tipping point: in a hot, dry climate a further 10% cut in water use can raise total energy use by 25%; in a cool, humid climate the cost is low.

Performance metricsWaterSustainability

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arXiv preprint (National University of Singapore) · 2025

A Bidirectional Gated Recurrent Unit Model for PUE Prediction in Data Centers

For an operations or digital-twin module, use the feature list as a practical minimum sensor set for PUE prediction: outdoor dry/wet-bulb, IT power, UPS power, CRAC power/capacity/SCOP, coil temperatures and airflow.

• RFECV selected feature sets of {21, 28, 29, 32, 33, 43} features with the minimum MSE.

Performance metricsEnergyCooling

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ASHRAE (ASHRAE Transactions Vol. 131 Pt. 2) · 2025

A Chilled-Water-Cooler-Capacity Model for Data Center CFD and Other Cooling Digital Twins (ASHRAE 2025 Annual Conference, PX-25-075)

Chilled-water CRAH/fan-wall catalogue items should store rated capacity with its rating conditions (EWT, return air temperature, airflow, water flow).

• Related standard: ASHRAE Standard 127.

CoolingAirflow

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Energies (MDPI AG) · 2020

A Comparative CFD Study of Two Air Distribution Systems with Hot Aisle Containment in High-Density Data Centers

In high-density HAC halls, prefer a raised floor to hard-floor supply; on a hard floor high-velocity jets can starve the racks nearest the CRAHs and draw hot air back into them.

• On the hard floor, supply velocities of 10 m/s or more persisted to the eighth rack position, versus the fourth with a raised floor.

AirflowCoolingReliability

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arXiv preprint (Texas Tech University / PNNL; submitted to Renewable and Sustainable Energy Reviews) · 2026

A Critical Review of Grid Integration Challenges and Flexibility Opportunities for Large-Scale Data Centers

Base interconnection studies on staged, updatable facility data rather than a single static MW value; requested peak MW and annual energy alone do not establish integration.

• Under IEEE 519-2022, voltage-distortion limits at the PCC are the system owner's responsibility and current-distortion limits are the user's; a scalar THD cannot rule out narrow-band resonance.

ElectricalReliabilitySustainability

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Proceedings of the Twelfth ACM International Conference on Future Energy Systems (ACM) · 2021

A Guide to Reducing Carbon Emissions through Data Center Geographical Load Shifting

For geographic load shifting, consider locational marginal carbon emissions (lambda-CO2) as the signal instead of LMP or regional average carbon intensity; it gave the largest reduction (-1.44%).

• Lambda-CO2 shifting saved about 0.14 t CO2 per MW shifted and still reduced generation cost by 0.27%; LMP shifting cut cost by 1.07% but saved less carbon.

SustainabilityEnergyOperations

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Frontiers in Sustainability (Frontiers Media SA) · 2023

A material social view on data center waste heat: Novel uses and metrics

In data-centre siting, look beyond PUE to energy source (EnergyIn) and heat reuse (EnergyReuse), which PUE ignores.

• Proposed metric: DESS = 3 × EnergyIn + EnergyCompute + 2 × EnergyReuse, where each constituent lies between 0 and 1.

SustainabilityPerformance metricsSite planning

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IEEE Access (Institute of Electrical and Electronics Engineers (IEEE)) · 2021

A Novel Reliability Index to Assess the Computational Resource Adequacy in Data Centers

Set the number of spare PSUs/servers in a rack with a LOWP-style calculation from target service reliability and the load duration curve, avoiding unnecessary overprovisioning.

• The rack model assumes 10 blade servers rated 800 W each (400 W idle) with 40 local fans.

ReliabilityRacksElectrical

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ACM/SPEC · 2014

A Power-Measurement Methodology for Large-Scale, High-Performance Computing (ICPE 2014)

In the metering design module, offer Level 1/2/3 templates that place meters (for example upstream of PSUs/PDUs) and set the required coverage and sampling.

• Related references: EE HPC WG Power Measurement Methodology, ISO/IEC 30134-2.

Performance metricsEnergyElectrical

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IEEE Access (Institute of Electrical and Electronics Engineers (IEEE)) · 2021

A Review of Data Centers Energy Consumption and Reliability Modeling

Define the failure state (loss of PDU power, loss of a rack, loss of service) explicitly before starting a reliability study and state it in the report.

• Cooling-system operational availability is AO = 1/(λsys/µsys + 1) and functional availability is Af = AO(1 − pus) + (1 − AO)·pt.

ReliabilityElectricalEnergy

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Energies (MDPI AG) · 2023

A Review of Flywheel Energy Storage System Technologies

In UPS designs that only need bridging until the generator starts, evaluate a flywheel as a battery alternative, checking that a 15 s-15 min discharge range and a generator start under 10 s are adequate for the duty.

• Flywheel operating temperature range is -40 to +50 °C, with low environmental requirements and no contamination.

UPSEnergyReliability

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Energies (MDPI AG) · 2020

A Review of Lithium-Ion Battery Fire Suppression

In Li-ion UPS and BESS areas, set up detection with combined smoke-heat detectors; do not rely on heat detectors alone.

• In DNV-GL tests, F500, FireIce, PyroCool foam, Stat-X aerosol and sprinklers all extinguished the fires, but the water-based systems cooled better over time.

Fire safetyUPS

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Energies (MDPI AG) · 2025

A Review of Non-Uniform Load Distribution and Solutions in Data Centers: Micro-Scale Liquid Cooling and Large-Scale Air Cooling

For high-heat-flux chips, weigh the pump-power increase of complex microchannel cold-plate geometry against the thermal-resistance gain (for example 11.8%).

• Chip heat flux is described as reaching ultra-high levels of 10^6-10^7 W/m².

Liquid coolingAirflowCooling

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Fluids (MDPI AG) · 2026

A Review of Thermal Management in Modern Data Centres: Water Usage Effectiveness and Heat Transfer Coefficients

Set WUE targets from the heat-rejection topology (dry, free-cooling, hybrid, evaporative) and not only the server-side cooling technology; WUE depends on the share of heat rejected by evaporation.

• Dry facilities with closed-loop liquid cooling need essentially no water, while evaporative systems typically report WUE up to 2.5 L/kWh.

WaterCoolingLiquid cooling

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Energies (MDPI AG) · 2021

A Study on the Energy Reduction Measures of Data Centers through Chilled Water Temperature Control and Water-Side Economizer

In a central plant without a WSE, raise the chilled-water supply setpoint to about 11 °C; at 15-17 °C, CRAH fan energy increased total energy.

• Overall reductions against the conventional model were 1.8% (higher setpoint), 19.6% (adding WSE) and 30.1% (WSE with delta-T control).

CoolingEnergy

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Electronics (MDPI AG) · 2025

A Systematic Review of Energy Efficiency Metrics for Optimizing Cloud Data Center Operations and Management

In efficiency reporting do not make PUE the only metric; knowing its weaknesses (manipulation, optimal-condition reporting, ignoring IT utilisation), complement it with WUE, CUE and IT-side metrics (SPUE, PpW, ITEE).

• Google reported a 2023 fleet-average annual PUE of 1.10 against an industry average of 1.58; Microsoft reports PUE and WUE together.

Performance metricsEnergyUPS

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Technology Review for Carbon Neutrality (Tsinghua University Press) · 2025

Accelerating liquid cooling adoption in data centers: necessity, challenges and solutions

For racks where GPU/accelerator thermal design power exceeds 1,200 W, take liquid cooling as a mandatory design input, and weigh the initial cost (about 1.9-2.2 times air cooling) against TCO (up to 20% lower after 4 years, vendor figure).

• Cooling systems in air-cooled data centres consume around 40% of total data-centre energy.

Liquid coolingReliabilityEnergy

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Applied Energy (Elsevier BV) · 2025

Accounting carbon emissions from electricity generation: a review and comparison of emission factor-based methods

In data-centre carbon accounting, state the method (Tier 1, 2, 3) and factor source (IPCC or national) when choosing a grid emission factor; simple methods can underestimate generation emissions by about 73%.

• AEF for the North zone by Method 5 rose from 0.1627 tCO2/MWh in 2016 to 0.4709 in 2022, then fell to 0.3936 in 2023.

SustainabilityEnergyPerformance metrics

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arXiv preprint (University of Alberta) · 2025

AI Load Dynamics - A Power Electronics Perspective

Include rack-level templates for AI racks (32-34 kW air-cooled, 73-132 kW liquid-cooled NVL) with per-GPU power.

• Rack PSU bandwidth of 30-50 ms bounds the fastest net swing upstream.

ElectricalRacksUPS

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arXiv preprint (Cadence Design Systems) · 2026

AI-driven Thermal-aware Data Center Capacity Planning

For layout iteration and add-load what-ifs, a surrogate that predicts only cabinet-inlet temperature (the compliance quantity) is cheaper and more accurate than full-field surrogates.

• As a practical guideline, an initial dataset is about 500 simulation cases with around ten randomised parameters.

AirflowRacksOperations

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Energies (MDPI AG) · 2018

Analysis of Air-Side Economizers in Terms of Cooling-Energy Performance in a Data Center Considering Exhaust Air Recirculation

In airside economiser design, plan exhaust grilles and the building envelope so recirculation stays below 5%; 15% recirculation raised energy about 6.1% for direct and 9% for indirect.

• The authors recommend placing exhaust-air grilles so recirculation is below 5%, or handling it in the envelope plan at design stage.

CoolingAirflowEnergy

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ITEGAM- Journal of Engineering and Technology for Industrial Applications (ITEGAM-JETIA) (GN1 Sistemas e Publicacoes Ltd.) · 2021

Analysis of Power Quality Parameters at Comparing UPS of Different Technologies

Choose online double-conversion UPS for loads where power quality improvement is expected; an offline UPS passes harmonics and unbalance through to the load side.

• Output power factor: offline UPS 0.95, online UPS 0.97 (PRODIST range 0.92-1.00).

UPSElectrical

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Standards (MDPI AG) · 2026

Arc-Flash Hazards: Standards Development Framework in Facilities of National Importance in Healthcare and Data Centers

Schedule the arc-flash study after the coordination study and make that order a mandatory step in the project plan and model.

• Example studies assumed available utility fault current of 21,000 A for the 440 V residential service and 21,000-40,000 A for the 480 V/1200 A commercial service.

ElectricalOperationsCommissioning

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Energies (MDPI AG) · 2023

Artificial Intelligence-Based Temperature Twinning and Pre-Control for Data Center Airflow Organization

For an operational thermal twin, define adequate sensor density covering supply, return, cold-aisle and hot-aisle temperatures and equipment power (728 points at 15-minute sampling in this study).

• The DQN controller cut PUE by an average of 2.6% and WUE by 2.5% over a year.

AirflowOperationsCooling

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