What Data Centers Teach us about Energy Efficiency

What defines an energy-efficient building? How can building operations be designed to remain economically viable while conserving resources? How can losses be avoided and surplus energy be fed back into the cycle?

Questions relating to energy efficiency and decarbonization are becoming increasingly relevant in light of rising CO₂ and energy prices, dependence on energy imports from critical regions, stricter regulatory requirements, and growing demands for transparency regarding energy consumption. Reducing energy costs and increasing energy efficiency not only benefit people and the environment, but also reduce economic risks and contribute to overall economic stability.

One thing is clear: energy efficiency is not a single technical parameter. Rather, it describes how consistently a building handles energy – from supply and use through to reuse. The key question is not simply how consumption can be kept as low as possible, but how the energy used can be optimized to avoid losses and keep energy within the cycle. Achieving this requires a holistic perspective and a corresponding concept that takes all technical requirements into account as a whole.

Holistic Planning With a Focus on Energy Efficiency
Optimized energy efficiency can only be achieved when all relevant disciplines are considered together from the outset. Individual optimizations fall short if they are not embedded within an overarching solution. This is particularly evident in the interactions between individual systems. For example, the choice of cooling system influences not only energy demand, but also the potential for waste heat utilization and water consumption. At the same time, the available energy infrastructure affects the design of technical systems. Decisions in one area therefore have direct consequences for others. Our experience in interdisciplinary collaboration enables us to identify these dependencies at an early stage and coordinate them effectively.
Another key aspect is the integration of local conditions. Available grid capacities, climatic conditions, and potential consumers of waste heat have a significant impact on planning. One thing is certain: there is no universal solution. Every building requires a tailored system that depends on both its technical requirements and the specific local conditions and opportunities.

Measures to Optimize Energy Efficiency
Data centers are a prime example of energy-intensive buildings, consuming enormous amounts of electricity and water. They clearly demonstrate what matters in energy-efficient buildings and their Building Services systems – and where the greatest opportunities for optimization can be found.
The challenge in data centers is that virtually 100% of the electricity consumed by IT components is converted into heat, which must then be continuously removed to prevent overheating. The task is therefore not only to provide energy for operations, but also to direct that energy efficiently and enable its continued use wherever possible.

The following factors are particularly relevant to data centers, but are also applicable to other building types:Energy efficiency as a central objective: Regulatory requirements are placing increasingly stringent demands on Power Usage Effectiveness (PUE) and the use of renewable energy sources.

• Challenges in power supply: In urban areas, the provision of large electrical capacities is often limited. Industrial locations offer greater grid capacity but fewer opportunities for waste heat utilization.

• Cooling optimization: A combination of free cooling, air and liquid cooling, and new technologies such as immersion cooling is essential for improving efficiency.

• Waste heat utilization as an opportunity: Feeding waste heat into district heating networks becomes more economical as supply temperatures decrease. Direct hot water cooling (DHWC), in particular, enables direct heat transfer without a heat pump.

• Water supply as a critical factor: Water consumption can be minimized through closed-loop systems and innovative cooling technologies.

Power Supply: More Than Simply Providing Energy
Energy supply forms the foundation of every building. In energy-intensive applications, however, it quickly becomes clear that it is more than just a question of connection capacity.
As electricity demand increases, available infrastructure is increasingly becoming a limiting factor – or, viewed positively, a location advantage. Existing grids are reaching their capacity limits, particularly in urban areas. At the same time, requirements are changing. Alongside availability, reliability and sustainability are becoming increasingly important. Redundant systems ensure stable operations even in the event of failures, while the integration of renewable energy sources is gaining significance.

Cooling: The Key to Efficiency
In data centers, a significant proportion of the energy consumed is used for cooling. This is where the actual efficiency of the building and its Building Services systems is largely determined. The objective is to remove heat as efficiently as possible. Various approaches are available, each offering specific advantages.
One particularly effective solution is so-called free cooling, which uses outdoor air temperatures to dissipate heat. This requires suitable external conditions. When these conditions are met, cooling energy demand can be significantly reduced.
The organization of airflow within the building also plays a crucial role. Systems such as hot-aisle and cold-aisle separation prevent air at different temperatures from mixing. This increases cooling efficiency and minimizes additional energy consumption.
However, as power densities continue to rise, air-based systems are reaching their limits. Liquid cooling offers new opportunities, as it can absorb and dissipate heat far more effectively. In practice, hybrid solutions that combine different systems are increasingly common. These allow operators to respond flexibly to varying operating conditions and further improve efficiency.

Water: Often Overlooked but Essential
Another key factor is water. It is used primarily for cooling and has a significant impact on the efficiency of the overall system.
Demand depends heavily on the technology employed. While some systems require continuous water consumption, modern solutions increasingly rely on closed-loop systems. The objective is to keep water within the system, minimize losses, and use available resources efficiently. This includes concepts such as water treatment, recycling, and the use of alternative water sources.

Waste Heat: From Byproduct to Resource
One of the greatest opportunities for increasing energy efficiency lies in the utilization of waste heat. What is initially generated as a byproduct can – and increasingly must – be put to productive use. Under Germany’s Energy Efficiency Act (EnEfG), 20% of waste heat must be deliberately reused from mid-2026 onward.
Waste heat can be fed into district heating networks or used directly in neighboring buildings. Temperature levels are a decisive factor. Higher waste heat temperatures facilitate direct use, while lower network temperatures reduce thermal losses within heating networks.
New technologies, particularly in liquid cooling and heat pump development, are creating additional opportunities. They make heat available at temperature levels that enable direct utilization.

Building Automation: Efficiency Through Intelligent Monitoring
Finally, building automation is a crucial component of energy-efficient data centers. Intelligent control systems ensure optimized operation of both technical systems and IT infrastructure. Measurement and metering concepts are used for monitoring purposes and enable continuous supervision of operations as well as all cooling and waste heat components. This makes it possible to track energy flows, identify inefficiencies, and simulate failure scenarios in advance.

Integrated Collaboration as a Prerequisite for Energy-Efficient Buildings
As outlined above, energy efficiency is not achieved through isolated measures, but through a consistent and comprehensive Building Services concept. The example of data centers demonstrates that energy supply, cooling, water management, and waste heat utilization must be considered together and coordinated as an integrated system.
For Building Services measures to achieve their full impact, Building Services must be an essential component of the planning process. All disciplines must work together from the very beginning – not alongside one another or sequentially. On equal footing, interdisciplinary, and simultaneously. The integrated design approach that forms the foundation of our identity as a competence platform for the built environment is not an additional planning step, but a fundamental mindset. It brings together the expertise of all planning disciplines and provides the basis for cross-disciplinary knowledge exchange. This creates the foundation for energy-efficient and future-proof buildings.

ATP sustain combines expertise gained from research and building operations in the fields of energy efficiency, CO₂ optimization, and climate protection with a clear focus on economic viability. ATP sustain’s experts develop energy concepts, CO₂ audits, and climate action roadmaps for new buildings, existing properties, and districts.