Beyond PUE: A Local-Impact Audit Framework for Data Center Environmental Accountability

Overview

Standard data-centre sustainability metrics (PUE, WUE, CUE) measure a facility's resource use and emissions intensity normalised to IT energy use, without directly representing local resource scarcity, infrastructure capacity or social footprint. This gap has become politically consequential: in the first quarter of 2026 alone, local opposition delayed or cancelled roughly $130 billion in projects across the United States. Uptime Institute's 2024 survey average PUE is 1.56, flat for five years, and only 41% of operators track water use; an estimated 40% of US data centres sit in regions of high or extreme water stress.

The authors propose a five-category, 0-100 audit score: energy, water stewardship, carbon/renewables, regulatory compliance and local disclosure. Base weights: energy efficiency 20% (PUE, ERE); water stewardship 25% (WUE, withdrawal versus permit cap, source type potable/reclaimed/seawater, % returned as wastewater); carbon/renewables 20% (CUE, renewable %, with 24/7 hourly matching weighted above annual matching). The design rests on four principles: weights adjusted for water stress and grid conditions, a compliance gate, a five-level data-verification maturity ladder, and quarterly trend reporting.

The water stewardship weight is raised according to a regional water-stress index (WRI Aqueduct), and the carbon weight is adjusted for local grid carbon intensity and headroom, so identical operating figures can score differently depending on location. Compliance gate: any unresolved major regulatory violation caps the composite score at a ceiling of 40 (suggested, subject to calibration) no matter how well the facility performs in other categories. Five-level verification maturity ladder for each metric: L0 no public data; L1 operator projection with no enforcement; L2 permitted cap with contractual penalties but no independent metering; L3 third-party (utility) metering verifying the cap; L4 continuous verification.

Applying it to three Illinois projects shows public records cannot support a verified score for any of them without a contracted audit relationship. Example: Project Cardinal (Yorkville) water projections moved from 500,000 to 310,000 to 350,000 gal/day, then to 42,500 gal/day after a redesign to air-cooled, closed-loop cooling, with a contractual penalty above 71,400 gal on any single day. Limits: the framework covers only on-site water and energy and does not yet include indirect water consumed in electricity generation; the weights and thresholds (for example the compliance ceiling of 40) are suggested and subject to calibration. It is a preprint.

Key points

1. Base weights: energy efficiency 20% (PUE, ERE); water stewardship 25% (WUE, withdrawal versus permit cap, source type, % returned as wastewater); carbon/renewables 20% (CUE, renewable %, 24/7 hourly matching weighted above annual matching).
2. The water stewardship weight is raised according to a regional water-stress index (WRI Aqueduct) and the carbon weight is adjusted for local grid carbon intensity and headroom, so identical operating figures can score differently by location.
3. Compliance gate: any unresolved major regulatory violation caps the composite score at a ceiling of 40 (suggested, subject to calibration).
4. Five-level verification maturity ladder: L0 no public data; L1 operator projection with no enforcement; L2 permitted cap with contractual penalties but no independent metering; L3 third-party metering verifying the cap; L4 continuous verification.
5. Uptime Institute's 2024 survey average PUE is 1.56, flat for five years, and only 41% of operators track water use; an estimated 40% of US data centres sit in regions of high or extreme water stress.
6. Project Cardinal (Yorkville) water projections moved from 500,000 to 310,000 to 350,000 gal/day, then to 42,500 gal/day after a redesign to air-cooled, closed-loop cooling, with a contractual penalty above 71,400 gal on any single day.
7. Limitation: the framework covers only on-site water and energy and does not yet include indirect water consumed in electricity generation.

Using it in design

• 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).
• Define water design commitments by permit cap, source type (potable, reclaimed, seawater) and share returned as wastewater; redesign to air-cooled closed loop cut daily withdrawal from 350,000 to 42,500 gal/day.
• Use a five-category audit score of this kind as a screening tool for local opposition risk, but state that weights and thresholds are suggested and subject to calibration.

Who should read it

Planners and policy specialists preparing data-centre siting, environmental accountability and local community-acceptance files.

Document contents

1. Introduction
2. Proposed local-impact audit framework (five categories, weights, compliance gate, verification maturity ladder, quarterly trend reporting)
3. Illinois case application (Project Cardinal Yorkville, Meta DeKalb and other projects)
4. Discussion and limitations
5. Conclusion

Related standards

• ISO/IEC 30134-2
• ISO/IEC 30134-6
• ISO/IEC 30134-8
• ISO/IEC 30134-9
• EU Code of Conduct for Data Centres

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Publication details

Authors

Sharifa Sultana; Syed Ishtiaque Ahmed

Publisher

arXiv preprint (cs.CY; formatted for ACM e-Energy '26)

Year

2026

Document number

arXiv:2609.23421

Document language

English

Source type

Scientific

Access

Open licence — downloadable

DOI

10.48550/arXiv.2609.23421

Licence

CC BY 4.0 — share with attribution

Licence evidence

arxiv.org

Citation