Heat Reuse Subproject Update (OCP EMEA Summit 2025)

Overview

Presented by Petter Terenius, Gemma Reeves and Jaime Comella in the DC Sustainability track of the OCP EMEA Summit 2025 in Dublin, this deck is a status report from the Open Compute Project Heat Reuse subproject. It is freely accessible. The subproject comprises a reference-design white paper, policy research, an economics calculator and a readiness checklist. The deck is conference material and gives summary information rather than detailed justification.

The reference designs white paper covers a 3D model, line diagram, modular heat station, component table, room dimensioning table and demand matching. The deck also summarises what the designs cover: heat reuse room sizing, configurations, demand matching, boosting with heat pumps, heat-to-cooling and heat-to-power. The metrics considered are seasonality and intraday variation, impact on PUE, WUE and CUE, heat storage, and ERF and ERE measurement.

The policy section gives a round-up of EU, German and US state activity. Germany's Energy Efficiency Act sets a maximum PUE of 1.2 for new builds and 1.3 for existing sites, a minimum heat-reuse share of 10-20% for new builds and 100% renewable electricity. The EU EED requires reporting of PUE, ERF, REF, CUE and WUE. Findings say heat reuse can lower cooling costs by 10-30%, ease permitting and allow heat sales; New York State offers grants of up to USD 2M for heat-recovery projects.

A planned white paper will compare 1 MW heat-reuse scenarios in four geographies (Central Europe, Middle East, SE Asia and Virginia). The deck is a good pointer to the regulatory heat-reuse thresholds a European design must meet. Its limit is that it is a slide deck giving a summary rather than binding legal text; for legal obligations, the legislation itself should be consulted.

Key points

1. The reference designs white paper covers a 3D model, line diagram, modular heat station, component table, room dimensioning table and demand matching.
2. Metrics considered: seasonality and intraday variation, impact on PUE, WUE and CUE, heat storage, ERF and ERE measurement.
3. Germany's Energy Efficiency Act: maximum PUE 1.2 for new builds and 1.3 for existing sites, minimum heat-reuse share of 10-20% for new builds, 100% renewable electricity.
4. EU EED requires reporting of PUE, ERF, REF, CUE and WUE.
5. Heat reuse can lower cooling costs by 10-30%, ease permitting and allow heat sales; New York State offers up to USD 2M grants for heat-recovery projects.
6. A planned white paper compares 1 MW heat-reuse scenarios in four geographies (Central Europe, Middle East, SE Asia, Virginia).
7. Related documents: Directive (EU) 2023/1791, German Energy Efficiency Act (EnEfG) and ISO/IEC 30134-6 (ERF).

Using it in design

• Site and compliance rules should hold jurisdiction-specific targets (for example Germany: PUE 1.2 for new builds and 10-20% ERF).
• The tool should compute ERF/ERE when a heat-export interface is added.
• Define a heat-reuse room/plant object with sizing parameters, which would match the reference designs.
• Show the cooling-cost, permitting and heat-sale benefits of heat reuse as separate items in project economics.

Who should read it

Data centre designers, sustainability and policy specialists with heat-recovery and regulatory compliance goals in Europe.

Related standards

• EU Energy Efficiency Directive (EU) 2023/1791
• German Energy Efficiency Act (EnEfG)
• ISO/IEC 30134-6 (ERF)

Publication details

Authors

Petter Terenius; Gemma Reeves; Jaime Comella

Publisher

Open Compute Project Foundation

Year

2025

Document number

OCP EMEA Summit 2025, DC Sustainability track

Event

OCP EMEA Summit 2025, Dublin

Document language

English

Source type

Industry body

Access

Free to read

Licence

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

Citation