EnEfG §15: the Energy Reuse Factor ≥ 10 % from July 2026

TL;DR

• From 1 July 2026, new data centres ≥ 1 MW must demonstrate an ERF of ≥ 10 % — rising to 15 % (July 2027) and 20 % (July 2028).
• Breaches of construction and operating obligations carry fines of up to €100,000 per offence; other offences up to €500,000.
• The ERF requirement applies only to new builds; existing data centres are not directly subject to it.
• As an alternative to fulfilling the ERF, an operator can evidence an agreement with a municipality or heat network declaring the build-out of a network within ten years.
• A ministerial draft of the EnEfG amendment dated 9 April 2026 provides for relief — including a switch to cost-benefit analyses and voluntary reporting for waste-heat duties.
• For energy providers, the ERF mandate opens a concrete negotiating position: they become the statutorily provided heat sink.

1. Background

Data centres are one of the fastest-growing energy consumers in Germany. Annual electricity consumption is around 18 billion kilowatt-hours — roughly 3 % of total German electricity use. A decade ago it was 11 billion kWh and the trend continues upward. The main driver is the AI boom: industry observers estimate that data-centre electricity consumption could double again by 2030.

With the Energy Efficiency Act (EnEfG), in force since 18 November 2023, the legislator responds to this trend with a sector-specific, mandatory framework — for the first time binding and fine-enforced. The core instrument for new builds is the Energy Reuse Factor (ERF), regulated in § 11 para. 2 EnEfG. It measures what share of the energy consumed in the data centre is passed on to third parties in a usable form — typically as waste heat — or reused internally. The calculation method is laid down in DIN EN 50600-4-6.

The timing is deliberately political: the EU Energy Efficiency Directive (EED 2023/1791) entered into force in October 2023 and obliges all Member States to reduce joint energy consumption by 11.7 % against the 2020 reference by 2030. Germany transposed this with EnEfG — and went beyond the EU minimum in places, which is now subject to the ongoing amendment debate.

2. Data: the duties in detail

ERF thresholds and deadlines

Requirements apply to data centres with a non-redundant nominal connected load of at least 1 MW that are commissioned after 1 July 2026. The ERF rises in stages: ≥ 10 % from July 2026, ≥ 15 % from July 2027, ≥ 20 % from July 2028. The requirements must be permanently achieved at the latest two years after commissioning.

Commissioning	ERF minimum	New PUE limit	Deadline
from 1 July 2026	≥ 10 %	≤ 1.2	at latest 2 yrs after COD
from 1 July 2027	≥ 15 %	≤ 1.2	at latest 2 yrs after COD
from 1 July 2028	≥ 20 %	≤ 1.2	at latest 2 yrs after COD
before July 2026 (existing)	no ERF duty	≤ 1.5 from July 2027, ≤ 1.3 from July 2030	staggered

Sources: § 11 para. 2 EnEfG (BGBl. 2023 No. 294); Data Center Group (2024)

Scope

Affected are all data centres with a non-redundant nominal connected load above 300 kW. Only network nodes that predominantly do not process data are exempt. The 300 kW threshold applies per site.

Evidence duties

ERF evidence is submitted via the Energy Efficiency Register at the Federal Office for Energy Efficiency (BfEE) at BAFA. Operators must report consumption, PUE, cooling systems and waste-heat use annually by 31 March. From 1 January 2026, validation or certification of the energy or environmental management system is additionally required from 1 MW connected load (private operators) or 300 kW (public entities).

Penalty framework

If an energy or environmental management system is not, not correctly, or not timely established, the fine is up to €100,000. The same applies to breaches of the construction and operating requirements in § 11 paras. 1 and 2, and to breaches of the waste-heat duty in § 16 para. 1. In all other fine-bearing cases under § 19 para. 1, fines up to €500,000 may be imposed. Enforcement is by BAFA on a sample basis.

Exceptions and exemptions

The Act provides several exits: Agreement solution — operators can evidence an agreement with a municipality or heat network declaring the concrete intention to build a network within ten years. Capacity presumption — if the heat network operator does not respond to an enquiry within six months, sufficient capacity is statutorily presumed. Exemption for small heat-supplying plants — data centres that feed at least 50 % of their waste heat into a heat network are exempt from the management-system duty if their annual consumption is below 7.5 GWh.

EU context and amendment dynamics

With the EnEfG, Germany goes beyond the minimum measures set out in the EED for data centres. The European Commission initiated infringement proceedings after Germany missed the EED transposition deadline in October 2025. The April 2026 ministerial draft amendment provides that the ERF obligation would no longer apply where no technically and economically reasonable connection to an existing or planned heat network is available within a 5 km radius. Whether this draft becomes law in that form is open at press time (April 2026).

3. Implications for operators and energy providers

For operators, § 15 / § 11 para. 2 EnEfG is a planning obligation first: anyone commissioning a data centre ≥ 1 MW after 1 July 2026 must design waste-heat use from the outset — not retrofit it. That means cooling systems, heat exchangers and connection infrastructure must be integrated in the build phase. Experience from live projects shows this can cause significant retrofit cost in air-cooled data centres — water-cooled systems have a structural advantage here.

For energy providers, EnEfG fundamentally changes the negotiating logic with data-centre operators. They are now the statutorily provided heat sink. The heat network operator is obliged to inform the data-centre operator about the network's capacity. Not responding triggers the capacity presumption. At the same time, rising demand for ERF-compliant heat offtake contracts opens a new revenue category.

Pricing of such heat supply contracts is not defined in the Act. Waste heat is, in principle, not remunerated — minimum tax amounts are taken into account. In practice, levelised-cost models are frequently negotiated.

4. Where P2H connects

The P2H model addresses exactly the regulatory gap § 11 para. 2 EnEfG exposes: smaller and mid-sized energy providers often lack the capacity to actively acquire contracts with data-centre operators or to build their own waste-heat infrastructure. P2H's containerised compute modules feed waste heat at 60–75 °C directly into existing district heating networks.

Limits of the model: the 60–75 °C supply temperature is only usable for older district-heating generations (3G networks with 80–95 °C supply) with a heat-pump stage. For modern 4G networks (55–70 °C), direct feed-in is technically compatible. Suitability must be assessed site-specifically.

5. Outlook and open questions

The ERF mechanism sits in an active regulatory tension: the applicable EnEfG sets strict thresholds, the amendment draft (April 2026) would largely dissolve them for sites without heat-network connection. For operators, that means planning uncertainty.

For energy providers three follow-up questions are concrete: by when must a capacity response be issued to requesting operators? How is the concept of levelised cost to be interpreted? And what municipal-law consequences follow from letters of intent under the agreement solution? These questions are, to date, not conclusively resolved by the courts or a BAFA guidance note.

Sources

1. EnEfG §§ 11–15 — German Energy Efficiency Act, BGBl. 2023 No. 294. https://www.gesetze-im-internet.de/enefg/BJNR1350B0023.html
2. Government EnEfG draft bill (draft version), BMWK. https://www.bundeswirtschaftsministerium.de/Redaktion/DE/Downloads/Gesetz/entwurf-enefg.pdf
3. Taylor Wessing (2024): Passage of the Energy Efficiency Act. https://www.taylorwessing.com/de/insights-and-events/insights/2023/10/verabschiedung-des-energieeffizienzgesetzes-im-bundestag
4. BfEE / BAFA (2024): Energy Efficiency Register for data centres. https://www.bfee-online.de/BfEE/DE/Effizienzpolitik/Energieeffizienzregister_Rechenzentren/energieeffizienzregister_rechenzentren_node.html
5. Kapellmann Rechtsanwälte (2024): EnEfG — new duties for data-centre operators. https://kapellmann.de/de/beitraege/das-energieeffizienzgesetz-enefg-neue-aufgaben-fuer-unternehmen-und-betreiber-von-rechenzentren
6. DENEFF (April 2026): EnEfG 2026 amendment explained. https://deneff.org/energieeffizienzgesetz-enefg-novelle-2026-erklaert/
7. Directive (EU) 2023/1791 on energy efficiency (EED). https://energy.ec.europa.eu/topics/energy-efficiency/energy-efficiency-targets-directive-and-rules/energy-efficiency-directive_en
8. ZfK (April 2026): What the new EnEfG draft actually means. https://www.zfk.de/politik/deutschland/enefg-reform-referentenentwurf-sparquoten-wegfall
9. Bird & Bird (2023): Energy efficiency becomes a duty. https://www.twobirds.com/de/insights/2023/germany/energieeffizienz-wird-zur-pflicht
10. DIN EN 50600-4-6 — Energy reuse factor calculation standard. Beuth Verlag.