White paperCitationEditor’s pick
The Green Grid 2008
WP#14 - The Green Grid Metrics: PUE/DCiE Detailed Analysis
In the PUE/DCiE calculator, cite this paper as historical provenance.
- Registration required; related standard ISO/IEC 30134-2.
Topic guide
Performance metrics
Explore publications on PUE and other data centre performance indicators. Before using a metric for comparison or design decisions, check its measurement boundaries, calculation method and required inputs against the original reference.
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- 2007–2026
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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.
Technical guideCitation
Uptime Institute 2018
2018 Data Center Industry Survey Results (8th annual) - report landing page
Use as a historical data point for 2018 in a PUE and rack-density benchmark chart (PUE 1.58).
- Average PUE was reported as 1.58 in 2018 (as cited in a later Uptime publication).
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White paperCitationEditor’s pick
The Green Grid 2008
WP#14 - The Green Grid Metrics: PUE/DCiE Detailed Analysis
In the PUE/DCiE calculator, cite this paper as historical provenance.
- Registration required; related standard ISO/IEC 30134-2.
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.
Technical guideCitation
Uptime Institute 2018
2018 Data Center Industry Survey Results (8th annual) - report landing page
Use as a historical data point for 2018 in a PUE and rack-density benchmark chart (PUE 1.58).
- Average PUE was reported as 1.58 in 2018 (as cited in a later Uptime publication).
White paperFree to read
Schneider Electric 2023
3 Steps to Calculate Total Enterprise IT Energy Consumption Using DCIM
Model each meter point as a power-tree node with an aggregate flag so roll-ups never sum a parent and its child.
- Unmetered devices: 60% of manufacturer rating x assumed hours of use.
Technical guideFree to read
Upsite Technologies blog 2014
4 Steps to Reducing Bypass Airflow
Compute CCF for each room from running cooling capacity and IT load and show it as a KPI, with a warning when it is high (oversupply).
- CCF = rated capacity of running cooling units (kW) / (1.10 x IT critical load kW); the 10% covers lights, people etc.
Research paperFree to read
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.
Research paperPDF
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.
Research paperFree to read
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.
Research paperPDF
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.
Research paperPDF
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.
Research paperPDF
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.
RegulationPDF
European Commission 2026
Annexes 1 to 3 to Commission Delegated Regulation C(2026) 3472 - EU data centre energy (PUE) and water (WUE) efficiency classes, data centre label, and amendments to Delegated Regulation (EU) 2024/1364
Translate PUE and WUE targets into A-G classes: class A needs a design PUE of 1.15 or below and WUE of 0.1 or below; the class D boundary is 1.5 and 0.6. Write the class target into the design specification.
- WUE classes: A <= 0.1; B 0.1-0.2; C 0.2-0.4; D 0.4-0.6; E 0.6-0.8; F 0.8-1.0; G > 1.0.
StandardCitation
ASHRAE 2020
ANSI/ASHRAE Standard 127-2020, Method of Testing for Rating Computer and Data Processing Room Unitary Air Conditioners
In the CRAC catalogue, record rated capacity and efficiency (NSenCOP) on the basis of AHRI 1360 / ASHRAE 127 test conditions.
- Standard 127-2020 is listed with product code 86408.
StandardFree to read
ASHRAE 2022
ANSI/ASHRAE Standard 90.4-2022, Energy Standard for Data Centers - ASHRAE fact sheet
In the compliance calculator, compute annualised MLC and design ELC per segment (UPS, distribution, PDU) and compare them with climate-zone limits.
- The standard applies to data centres with power density above 20 W/ft2 and IT load above 10 kW.
StandardCitation
ASHRAE 2024
ASHRAE Datacom Series (TC 9.9) - series overview incl. IT Equipment Power Trends 3rd ed., Best Practices for Datacom Facility Energy Efficiency 2nd ed., Particulate and Gaseous Contamination 2nd ed., Green Tips
Use Book 2 (IT Equipment Power Trends) for default kW-per-rack growth projections.
- Book 10: Green Tips for Data Centers (2011), product 90554.
Technical guideFree to read
Consulting-Specifying Engineer 2019
ASHRAE's energy standard for data centers turns three
Implement the 90.4 MLC and ELC calculators with the correct test load points per UPS redundancy class (N/N+1 vs 2N).
- Annualized MLC requires an hourly energy simulation, also checked at 100% and 50% ITE load.
Research paperPDF
arXiv preprint (cs.AI), Harvard T.H. Chan School of Public Health 2026
Assessing the Carbon Emissions and Energy Consumption of U.S. Hyperscale Data Centers
In fleet or facility energy estimation, use capacity × 8,760 × facility-load coefficient (0.48-0.70, central 0.58) and report the range (67.7-98.6 TWh) explicitly.
- State-level intensities (central scenario): Virginia 535, Oregon 440, Iowa 645, Nebraska 740, Wyoming 1035 gCO2/kWh; Virginia had 142 HDCs, 21.0 TWh, 11.5 Mt.
Technical guidePDF
European Commission, DG ENER (AIT, Borderstep Institute, EY) 2025
Assessment of next steps to promote the energy performance and sustainability of data centres in EU, including the establishment of an EU-wide rating scheme - Second technical report
Align the PUE target of new designs with the proposed MPS: design PUE below 1.3 and operational PUE below 1.4 in the first three years; for existing sites plan the path to below 1.5 by 2030.
- MPS feasibility was tested across 27 data centre archetypes with selected best available techniques (BAT).
Technical guideFree to read
TMMOB Makina Mühendisleri Odası (MMO) 2023
Options for exergy-rational use of heat generated by CHP systems
In the energy module, when on-site CHP/trigeneration is modelled, report PUE together with source-aware metrics (primary energy, CO2 and optionally exergy-based figures).
- Related standard: ISO/IEC 30134-2.
Research paperPDF
arXiv preprint (cs.CY; formatted for ACM e-Energy '26) 2026
Beyond PUE: A Local-Impact Audit Framework for Data Center Environmental Accountability
In siting and community-acceptance files, present PUE, WUE and CUE together with regional water stress, grid headroom and verification maturity (L0-L4); back project commitments with contractual limits and independent metering (L2-L3).
- Compliance gate: any unresolved major regulatory violation caps the composite score at a ceiling of 40 (suggested, subject to calibration).
Technical guideFree to read
European Commission, DG ENER 2026
Call for evidence for an initiative with an impact assessment - Data centres in the EU: minimum performance standards (Ares(2026)8908107)
Track this initiative as an upcoming rule pack; leave design headroom against likely MPS indicators (PUE, WUE, waste-heat reuse readiness, grid flexibility).
- Legal basis is Article 194(2) TFEU; EU action is justified to avoid divergent national approaches.
Research paperPDF
arXiv preprint (cs.SE), Google 2024
Carbon accounting in the Cloud: a methodology for allocating emissions across data center users
In allocating carbon to data-centre users, give idle power to whoever holds the resource allocation and share dynamic power by actual usage; because an idle server draws about 45% of peak power, the idle share is large.
- Resources with equivalent busy power used to weight idle-power allocation: 1 Intel Skylake N1 CPU core = 20 GiB RAM = 1 TiB SSD = 6 TiB HDD.
StandardFree to read
ASHRAE 2022
Characterizing Data Center Cooling System Water Stress in the United States (2022 ASHRAE Annual Conference paper)
In site comparison, compute both site WUE and source (grid) water using a regional EWIF, and optionally a scarcity-weighted index.
- CRAC model: 100 kW per unit, 20 C supply air, 2.0 m3/s indoor and 4.0 m3/s outdoor airflow, COP varying with condensing temperature.
Technical guideFree to read
iMasons Climate Accord (Infrastructure Masons) 2025
Climate Accord Maturity Model: A Guide to Emissions Reduction in Digital Infrastructure, Version 1.1
Add embodied-carbon fields (kgCO2e; data source: EPD / TM65 / spend-based) to catalogue items and roll them up per design, reporting the share from supplier-specific EPDs.
- Data centers used about 460 TWh in 2022, nearly 2% of global electricity.
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