Energy-efficient data centres: a high-level overview - eu-LISA Research and Technology Monitoring Report 2026

Overview

This is the 2026 Research and Technology Monitoring Report (EL-01-26-007-EN-N) of eu-LISA, the EU agency for the operational management of large-scale IT systems. Prepared with input from Sopra Steria and RISE, it offers a high-level overview of data centre energy efficiency and sustainability. Its audience is not only specialist engineers but also decision makers at organisations that run their own data centres.

The report first explains the indicators: PUE, WUE, ERF, REF and others. It then reviews EU and international regulatory frameworks, including the Energy Efficiency Directive (EED) and the rules in Germany and Japan. For PUE it gives indicative bands: 1.2 or below is very efficient (state of the art, for example with liquid cooling), 1.3 or below efficient, 1.5 or below average, and 2.0 or below inefficient.

It also draws attention to the gap between design and operation. New or refurbished sites, for example those designed for a PUE of 1.3 but operating at 1.4, show this gap because of incomplete containment and blanking and low early utilisation. On waste heat, data centres integrated with district heating report an ERF of around 0.3-0.6; higher ERF usually requires liquid cooling, high outlet temperatures and urban proximity to heat demand.

On regulation, Japan's Energy Conservation Act sets a benchmark of PUE of 1.4 or less for server rooms over 300 m2 (the top 15%), to be tightened once more than half the industry meets it. The small EU survey found that many organisations running their own data centres lag in water monitoring and lifecycle sustainability management. The report also summarises innovation projects and hyperscaler practices.

Key points

1. PUE bands: <= 1.2 very efficient, <= 1.3 efficient, <= 1.5 average, <= 2.0 inefficient.
2. New or refurbished sites often show a design-versus-operation gap, such as designed for 1.3 but operating at 1.4, due to incomplete containment, blanking and low early utilisation.
3. Data centres integrated with district heating report ERF of about 0.3-0.6; higher values need liquid cooling, high outlet temperatures and urban proximity.
4. Japan's Energy Conservation Act benchmark for server rooms over 300 m2 is PUE <= 1.4 (top 15%), to be tightened once over half the industry meets it.
5. The survey found many organisations running their own data centres lag in water monitoring and lifecycle sustainability management.
6. The report explains PUE, WUE, ERF, REF and other KPIs and reviews EU and international regulation.
7. Related documents: Directive (EU) 2023/1791, Delegated Regulation (EU) 2024/1364 and ISO/IEC 30134.

Using it in design

• For novice users, show the band labels (very efficient, efficient, average, inefficient) as plain-language feedback next to the computed PUE.
• Add a design-to-operation gap allowance (for example +0.1 PUE) to early-life operational forecasts.
• Add an inspection of containment and blanking panels to the commissioning checklist.
• For projects planning heat recovery, treat liquid cooling, high outlet temperature and proximity to heat demand as preconditions for a higher ERF.
• Include water monitoring and lifecycle indicators in the sustainability report.

Who should read it

Engineers, corporate IT managers and policy specialists assessing data centre energy efficiency targets and regulatory compliance.

Related standards

• Directive (EU) 2023/1791
• Delegated Regulation (EU) 2024/1364
• ISO/IEC 30134

Publication details

Authors

eu-LISA

Publisher

European Union Agency for the Operational Management of Large-Scale IT Systems in the Area of Freedom, Security and Justice (eu-LISA)

Year

2026

Document number

EL-01-26-007-EN-N

Document language

English

Source type

Expert / community

Access

Free to read

DOI

10.2857/5626249

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation