Working and managing energy efficiently is not only important in times of energy shortages. That is why the legislature in Germany is prescribing precise targets with the new Energy Efficiency Act (EnEfG). The EU also intends to become the first climate-neutral continent on the planet by 2050 with the European Green Deal. Data centers in particular, as major consumers of electricity, are significantly affected. Great demands are therefore placed on the operators of data centers. In Germany, for example, they must demonstrate a Power Usage Effectiveness (PUE) of 1.3 for their data center by 2025. Furthermore, 75 percent of the energy used must come from sustainable and renewable sources. However, not every data center is equipped for the requirements of the future and not all sustainable parameters are always taken into account when planning new centers. What is needed are planning and restructuring approaches for data centers that take sustainability and the achievement of climate neutrality into account and integrate them as a driving factor.

Data centers are the backbone of digitization. In Germany alone, there are over 50,000, and the market is constantly growing due to the increasing demands due to the increasing data volume - annually by up to 15 percent. The area of cloud data centers alone rose over 150 percent in the period from 2016 to 2021. "The development of the amounts of data to be processed knows only one direction," says Harry Knopf, Managing Director of High Knowledge. As a solution developer, the Cologne-based consulting company has specialized primarily in sustainable data center planning with the goal of climate neutrality. “Increasing amounts of digital data are being processed. The annual data volume worldwide is up to 135 zetabytes. Data centers are now ubiquitous and can be found in every hospital, on public transport or in schools.”

However, data centers require an immense amount of energy. More than 3,000 data centers have a connected load of more than 40 kW. For comparison: In a single-family house, this output is ten kW. In total, the data centers in the country consumed over 16 billion kW per hour in 2020 - and the trend is rising here too. The so-called Power Usage Effectiveness (PUE), which puts the energy used for IT in relation to the electricity demand for the infrastructure, was 1.68 last year. "As early as 2025, according to the requirements of the federal government's new Energy Efficiency Act (EnEfG), this value may not exceed 1.3. Data center operators are therefore strictly required to implement the necessary measures over the next two years so that they can achieve their legally defined sustainability goals in accordance with the EnEfG," explains Knopf.

Great Challenges for the Future

The underlying climate goals of the federal government, but also of the EU, are clearly defined: By 2030, 100 percent of the energy used for data centers must come from sustainable sources - e.g. B. from wind and water energy. In addition, 40 percent of the waste heat must be reused. As of today, the waste heat is only used effectively in a few cases; for example, fed into the district heating network or used to heat buildings in the immediate vicinity. According to a study by the Bitkom Association, only five percent of data center operators reuse more than 50 percent or more of the waste heat. Only 20 percent make sensible use of ten to 50 percent of the heat generated. "This is exactly the big topic of the future and will therefore pose major problems for some data center operators," emphasizes Knopf. "There are many sensible ways to save energy when planning data centers and, above all, to use the waste heat sensibly."

For most operators, these are not facultative, optional measures; the EnEfG must meet specifications in the foreseeable future in order to ultimately achieve climate neutrality. Not only does the PUE have to be 1.3 by 2025, but by 2027 all data centers in the country are to be operated ecologically and sustainably. Furthermore, the minimum inlet temperature of the air on the server must be 27 degrees. Today, most data centers work at 21 degrees, which means that they have to be cooled down immensely. However, if you need a lower temperature for work, you have to do this without using an energy-consuming refrigeration system.

A Precise Overview Thanks to Sustainability Certification

In order to be prepared for the strict requirements of the future, you need partners who can take a holistic view of the situation. Because an energy-efficient data center is based on different elementary pillars. “It's about keeping an eye on all aspects when planning the tasks to be implemented. It's about the right cooling, the efficiency of the server or the question of location," explains Knopf. "By the way, this applies to the planning of a new data center as well as to the energy-efficient renovation of an existing center."

However, before concepts can be implemented, the current situation must be examined in detail, which is why the individual location is scrutinized. The infrastructure of the entire IT and the utilization of servers are also considered. In addition, sustainable planning also includes the close examination of water as an increasingly valuable and increasingly scarce resource. Based on the sustainability certification, a well thought-out, holistic view of a data center can then be carried out. In this context, for example, in the case of a new building, an assessment is also made of how the data center can later be sustainably dismantled and what use the building could then have.

Working Sustainably with the Elements

"Most operators of data centers don't even know where they stand when it comes to energy efficiency," continues Martin Vogt, Head of Technology at High Knowledge. Once such an analysis has been completed, concrete procedures for future-oriented optimization can be derived and implemented. For this z. B. High Knowledge is the holistic solution Blue DC Elements developed, which enables the implementation of climate-neutral IT infrastructure using building blocks. Depending on the local situation, certain advanced technologies can be used. "In many cases, unused potential can be identified and significantly reduced energy consumption achieved," says Knopf.

The building blocks are based on the four elements earth, fire, water and air. In addition to reducing electricity consumption, the central point is above all the introduction or optimization of the use of waste heat. For example, the waste heat in the server can be transferred to a water circuit and the heated water can be used for heating systems such as district heating networks. The waste heat can also be used directly to heat adjacent rooms or buildings. Blue DC Elements also shows how the operator can effectively cool with water. "The aim is to show that water is not consumed, but used," emphasizes Vogt. The topic of "air cooling" also provides enormous savings potential. However, the Blue DC Elements concept can be applied not only to new plans, but also to existing data centers. "Here, too, a PUE of even 1.0 can ultimately be achieved," Knopf promises.

Choose the best location

Another factor for an energy-efficient data center will be the location in the future. In most cases, such centers are now in the immediate vicinity of Internet hubs such as in Frankfurt am Main. In most cases, however, the waste heat is released directly into the atmosphere – without being used effectively. Knopf: “In the foreseeable future, new plans for data centers will definitely have to break new ground. Since the waste heat is completely released into the environment, as is unfortunately still often the case today, we have several negative effects at the same time. Energy is practically wasted and the waste heat also has a negative effect on the microclimate at the locations of the data centers - and the waste heat has such an enormous potential for meaningful reuse!" 

Concepts for economic use see e.g. B. the association with customers in the vicinity. For example, central data centers can be located next to kindergartens or schools, for which the waste heat then serves as a heat source. A connection to the district heating network should also always be planned for a new building. "Especially in today's discussion about high gas and energy prices, hardly anyone talks about the use of waste heat from data centers," notes Knopf. "Here, too, a lot of energy could be used sensibly, but in most cases it still vanishes into thin air."


Data centers are becoming more and more important due to the constantly growing digitization. However, this also increases energy consumption, for example for cooling the servers. Waste heat is generated here, which has not been used sensibly up to now. In addition, with the new Energy Efficiency Act, the legislator stipulates that up to 75 percent of the energy used will come from renewable sources by 2025. By 2030 it should even be 100 percent. In addition, the law stipulates that at least 40 percent of the waste heat must be used. The EU also has major goals that are to be achieved by 2050: by then the entire continent should be climate-neutral. In order to meet these strict requirements, data center operators need competent support and innovative solutions such as Blue DC Elements. Thanks to a holistic view, sustainability and energy efficiency can be increased, which means that more favorable PUE values can be achieved.