In short
- EU sites from 500 kW IT report energy reuse with PUE, WUE and REF since 15 Sep 2024.
- From 11 Oct 2025, sites above 1 MW total rated input must use waste heat unless it is not technically or economically feasible (EED Art. 26(6)).
- Germany's EnEfG sets ERF targets for new data centers: 10 % from Jul 2026, 15 % from Jul 2027, 20 % from Jul 2028.
- A cabinet draft of 24 Jun 2026 would replace the fixed targets with a cost-benefit test; until the Bundestag votes, the current law applies.
The timeline
| Date | Rule | Status |
|---|---|---|
| 15 Sep 2024 | First EU reporting: energy reuse, PUE, WUE, REF for sites ≥ 500 kW IT (EED Art. 12, Delegated Reg. 2024/1364) | In force |
| 11 Oct 2025 | EED Art. 26(6): sites above 1 MW use waste heat unless not feasible | In force |
| Jul 2026 | Germany: ERF 10 % for new data centers | In force |
| 21 Sep 2026 | EU sustainability rating proposed, including waste-heat reuse | Proposed |
| Jul 2027 | Germany: ERF 15 % | Upcoming |
| 15 Aug 2027 | Expected first EU ratings | Proposed |
| Jul 2028 | Germany: ERF 20 %, unless the amendment replaces it | Upcoming |
The same timeline is on the rules section.
EU: reporting first, then a duty to use
The recast Energy Efficiency Directive works in two steps. Article 12 and Delegated Regulation 2024/1364 make data centers of 500 kW IT or more report their energy, PUE, water use, renewable share and the energy they reuse to a European database. Article 26(6) goes further: sites with more than 1 MW total rated energy input must use their waste heat or other recovery applications, unless they show it is not technically or economically feasible.
The proposed EU sustainability rating would add labels that include heat reuse, with first ratings expected in 2027.
Germany: the Energy Efficiency Act (EnEfG)
Germany sets hard numbers for new data centers. The share of reused energy, the ERF, must reach 10 % for sites starting operation from July 2026, 15 % from July 2027 and 20 % from July 2028. The same law sets PUE limits and renewable electricity duties, covered on allinPUE.
The German draft of 24 June 2026
The federal cabinet's draft amendment would replace the fixed ERF steps with a cost-benefit analysis. Sites without a feasible heat network within 5 km would be exempt; offering the heat would be enough. Until the Bundestag votes, the law in force applies, so projects starting now should still plan for the 10–20 % targets.
What ERF counts
Heat that is offered but not taken does not count. That is why the seasonal use share and a firm offtake agreement matter as much as the engineering. Work out your ERF with the calculation guide.
What to do on a new project now
- Map heat networks and large heat users within 5–10 km before buying land.
- Choose a cooling design with the warmest practical return water; it decides the COP.
- Reserve space and connections for heat exchangers and heat pumps.
- Open talks with the network operator early; offtake agreements take time.
- Set up metering for ERF from day one; reporting is already required.
Questions about the rules
Do existing data centers have to reach the ERF targets?
The German ERF steps apply to new data centers. EU reporting and the Article 26(6) feasibility duty apply more broadly; check the transposition in your country.
What if there is no heat network nearby?
Under the EED a site can show that reuse is not technically or economically feasible. Germany's draft would exempt sites without a feasible network within 5 km.
Does ERF count the heat pump's output?
No. It counts the data center energy that is reused, so the heat pump's own electricity does not raise the ERF.
Is this legal advice?
No. It is a summary for planning. Check the current texts and get legal advice for a specific project.
Sources
- Directive (EU) 2023/1791 (EED) Art. 12 and 26(6); Delegated Regulation (EU) 2024/1364.
- German Energy Efficiency Act (EnEfG); federal cabinet draft amendment of 24 June 2026.
- Status as of October 2026; rules change, check the current versions.