From Simulation to Sustainability: Optimizing Integrated Cooling, Storage and Heat Recovery Systems

Michalis Mouratidis, Charitini Matsouka, Akrivi Asimakopoulou, Dimitris Koutsonikolas, ARTEMIS Laboratory, CPERI, CERTH, February 2026

As the digital world expands, data centers have become essential infrastructure supporting everything from cloud computing to artificial intelligence. However, their operation generates significant amounts of heat, which is typically treated as waste. Recovering and reusing this heat represents a major opportunity to improve overall energy efficiency and reduce environmental impact. To achieve this, advanced systems combining immersion cooling, thermal energy storage and heat recovery must be carefully designed and optimized.

Because of their complexity, these integrated systems cannot rely on physical testing alone. Instead, engineers develop detailed digital models and virtual environments that allow them to simulate, analyze, and optimize system performance under a wide range of operating conditions. These digital tools provide critical insight into how the system behaves, enabling smarter design decisions and more efficient operation.

Integrated Prototype Simulation and Optimization

The development of an integrated prototype begins with process modeling using specialized simulation software. This digital model represents the complete system, including immersion cooling units, heat exchangers, pumps, thermal storage modules and heat recovery technologies.

Initially, individual components are modeled separately. Gradually, all system elements – both primary and secondary components – are integrated into a unified process simulation scheme. This comprehensive approach ensures that all interactions between components are properly captured and evaluated. By considering the system as a whole, engineers can identify opportunities to minimize heat losses, reduce power consumption and optimize material usage.

Using steady-state simulations, mass and energy balance calculations are performed across multiple case studies. These calculations allow engineers to track how heat and energy flow throughout the system and identify the most important design and operational parameters. This step is essential for ensuring that the system operates efficiently and reliably under different conditions.

In addition, sensitivity analysis is carried out to evaluate how variations in key parameters affect system performance. Factors such as operating temperatures, flow rates, storage capacity and heat exchanger efficiency are systematically analyzed. This process helps determine the optimal specifications required to maximize system efficiency, reliability and overall performance.

Virtual System Development: Understanding Real-World Operation

While steady-state simulations provide valuable insights, real-world systems operate under dynamic conditions. Heat generation in data centers fluctuates depending on computing demand, while heat demand from external users may vary daily or seasonally. To address these challenges, our engineers develop a virtual system that simulates the interaction between the integrated energy system and its potential end users.

This virtual environment enables us to analyze how the system responds to changing conditions, including intermittent heat availability, variable energy demand, and seasonal storage opportunities. By modeling these real-world scenarios, we can evaluate how the system adapts to different time scales and operating conditions. This ensures that the integrated system remains stable, efficient, and responsive, even when operating under fluctuating loads. Ultimately, virtual system development helps ensure that the technology can function effectively in practical applications.

Techno-Economic Analysis and Life Cycle Costing

In addition to technical performance, economic viability is essential for the successful deployment of integrated energy systems. Techno-Economic Analysis (TEA) is performed to evaluate the financial feasibility of the proposed solution. The analysis is based on a full-scale system capable of meeting the cooling demands of a typical medium-scale data center with a capacity of approximately 1 MW. Both capital expenditures (CapEx), which include equipment and installation costs and operational expenditures (OpEx), such as electricity consumption and maintenance, are evaluated as functions of system capacity and energy prices.

These calculations allow engineers to identify the breakeven point and determine the optimal operating conditions that maximize economic performance. This ensures that the system is not only technically efficient but also financially sustainable.

Building on this analysis, Life Cycle Costing (LCC) evaluates the total cost of the system over its entire lifetime. This includes initial investment, operational costs, maintenance, and end-of-life considerations such as equipment disposal or recycling. By considering different operating scenarios and system boundaries, LCC provides a comprehensive understanding of long-term economic performance.

Assessing Environmental Impact through Life Cycle Assessment

Beyond technical and economic considerations, environmental sustainability is a key objective of integrated heat recovery systems. Life Cycle Assessment (LCA) is used to evaluate the environmental impact of the system across its entire value chain. This assessment includes both upstream processes, such as material extraction and equipment manufacturing, and downstream processes, including system operation and end-of-life management. The analysis follows internationally recognized standards, including ISO 14040 and ISO 14044, ensuring a consistent and scientifically rigorous methodology. By collecting and analyzing data on energy use, material consumption, and emissions, LCA helps identify opportunities to reduce environmental impact. This ensures that the proposed technology contributes meaningfully to reducing carbon emissions and improving overall sustainability.

Supporting the Future of Sustainable Data Centers

The integration of immersion cooling, thermal energy storage, and heat recovery technologies represents a promising solution for improving the energy efficiency of data centers. However, the successful implementation of such systems requires a deep understanding of their technical performance, economic feasibility, and environmental impact.

Through advanced simulation, virtual system development, techno-economic analysis, and life cycle assessment, engineers can design optimized systems that are efficient, cost-effective, and environmentally sustainable. These digital tools provide the foundation for smarter energy systems that can recover and reuse waste heat, reducing both operational costs and environmental footprint. As digital infrastructure continues to grow, integrated and optimized energy systems will play a critical role in supporting a more sustainable and energy-efficient future.