Waste heat utilisation

Waste heat utilisation

Waste heat utilisation or heat recovery is a central component in the engineering and operation of energy-efficient data centers. Waste heat generated by the operation of individual data center components can be captured, processed and passed on to ensure that CO2-free heat can be used to heat local office, commercial or residential buildings or to feed waste heat into a local or district heating network. The requirements for this must be realised, which the Data Center Group is implementing with its experts and with the help of MVV Enamic GmbH.

 

Pipes standing on a green meadow with a blue sky
2 hands operating and writing on a calculator. Plus a green miniature house

The Energy Efficiency Act for Data Centers (EnEfG) passed by the German government in 2023 requires mutual notification of load assumptions and consumers. Furthermore, data center operators must demonstrate a fixed proportion of reused energy.

This Energy Reuse Factor (ERF) is calculated from the quotient of the value of the reused energy and the total energy consumption of the data center. A high ERF value indicates that the data center is using energy effectively. A low ERF value indicates that less energy is recovered from the data center for other purposes.

According to the Energy Efficiency Act, the proportion of reused energy (ERF - Energy Reuse Factor) must be at least 10% when the data center is commissioned from 

  • 1.7. 2026 must be at least 10%,
  • 15% from 1.7. 2027 and 
  • 20% from 1.7.2028.

Further information on the Energy Efficiency Act can be found here:

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A man working on heat pumps and wearing a helmet and safety vest

Waste heat is generated in data centers when the servers are cooled. Recirculating air cooling is usually used, which is heated to around 35 degrees by the waste heat from the servers, for example. The circulating air is then exchanged for water via a circulating air cooling unit. This water with a temperature of around 25 to 27 degrees can then be made available for waste heat recovery. In contrast, with liquid cooling - usually with water - the waste heat is usually removed directly from the processor (CPU) and other relevant components. The waste heat temperature here can oscillate between 55 and 60 degrees.

Instead of transferring the heat directly (air cooling) or via a chiller (liquid cooling) to the environment, it can be connected to a local or district heating network to heat buildings or produce hot water. This usually requires individual solutions.

Further information on the advantages and disadvantages of water cooling can be found in the article:

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Pipes that transport heat

The waste heat from data centers cannot be used directly in a district heating network. The temperatures are too low for this. A district or local heating network is usually operated with flow temperatures of 70 to 130 degrees. The temperature of the exhaust air (air cooling) or hot water (liquid cooling) must therefore be increased using special, highly efficient heat pumps so that it reaches the level of the heating network and fluctuations in waste heat are balanced out. Liquid cooling offers better technical conditions here, as the heat is already available in liquid form.

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We ensure that waste heat can also be used in practice. The DENEFF consortium Bytes2Heat, in which we are a project partner, is developing innovative and forward-looking waste heat solutions.

Further information can be found here:

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2 people each have a piece of the puzzle in their hand

The Data Center Group is the competent partner for the climate-friendly and efficient use of waste heat in data centers. We apply our extensive expertise to the energy-efficient and economical use of waste heat and implement the technical interface for the transfer of waste heat to a customer.

We support our customers on their way to a sustainable data center and a sustainable heat supply to match.

You can find more information on waste heat utilization in our article:

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Shaping the future sustainable

Several hands hold a small miniature earth in green
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Sustainability in data centers start with planning

Architect's design: And this is what the new data center for Regio iT should look like
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Groundbreaking ceremony for the new climate-neutral data center of regio iT in Aachen

A flagship project for energy efficiency and sustainability

Heat pump in a small green shrub forest
News
Research project on waste heat utilization "Bytes2Heat" successfully completed

A final report and presentation of the tools developed to support a successful heat transition in the data center sector

Our measures for the green transformation

Waste heat recovery

We use accruing waste heat to generate heat

Certification

according to the Blue Angel eco-label

Photovoltaics & Facade Justification

Energy recovery and natural heat reduction of the IT protective shell

Research cooperation

We work on the topics of the future

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