Net-Zero Energy Design for a DataCenter in Stockholm

Sammanfattning

As the energy usage of data centers is anticipated to keep rising, concerns regarding environmental impact and energy use are raised. This issue can be addressed by developing Net Zero Energy Data Centers (NZEDCs)—facilities that combine innovative design, smart energy management, and external heat consumers. This thesis explores strategies for developing an NZEDC that conforms to ASHRAE standards. The study focuses on reducing energy consumption and integrating renewable energy sources by designing the facility with energy-efficient integrated HVAC systems featuring free cooling from outdoor air, combined with heat recovery to the district heating network and a rooftop PV system. Three cooling technologies were evaluated: air cooling, liquid-to-chip cooling, and dielectric fluid immersion cooling. Among these, immersion cooling achieves the highest COPSHC and lowest PUE, followed by liquid-to-chip and air cooling. Higher supply temperature improves free cooling availability and reduces the temperature lift required for integration with district heating networks, further enhancing system efficiency. The proposed systems performed well across KPIs and complied with ASHRAE standards. The scenario without heat recovery showed the highest COPSHC and lowest PUE, yet achieved only 1% of the NZEDC target. In contrast, the scenario with full heat recovery reached 88% of the target. A strategy combining free cooling and heat recovery achieved 24% of the NZEDC target, highlighting the importance of optimizing both strategies to support NZEDC goals. The main challenge in achieving full NZEDC target is the high and irreducible energy demand of IT equipment. Meeting the full NZEDC target would require an additional 5–24 MWp of ground-mounted PV capacity, depending on the scenario.