In the heart of Zagreb, Croatia, a groundbreaking project is redefining how commercial buildings can harness renewable energy. Marija Macenić, a researcher from the Department of Petroleum and Gas Engineering and Energy at the University of Zagreb, has led a pioneering study on the use of energy piles for heating and cooling a large non-residential complex. This innovative approach, detailed in a recent case study, could significantly impact the energy sector’s push towards sustainability and efficiency.
The project, which involved the installation of 260 energy piles, is a testament to the potential of shallow geothermal energy. These energy piles, integrated into the building’s foundation, serve a dual purpose: they provide structural support and act as heat exchangers, tapping into the Earth’s natural thermal energy. “The beauty of energy piles lies in their dual functionality,” Macenić explains. “They reduce the need for additional drilling, making them a cost-effective solution for large buildings.”
The Zagreb complex, designed with 13 separate dilatations, utilizes a bivalent parallel system. This system combines geothermal heat pumps with natural gas for peak heating loads and dry coolers for peak cooling loads. The geothermal source operates at full load for a significant number of hours, ensuring efficient use of renewable energy. “The geothermal system works efficiently at a bivalent point, covering total heating needs and about 70% of cooling requirements,” Macenić notes. This balance is crucial for maximizing the use of renewable energy while ensuring reliable performance.
The study involved conducting thermal response tests on two energy piles to determine thermogeological parameters and heat extraction rates. These tests are essential for optimizing the design and operation of the geothermal system. “Thermal response tests are integral to the construction process,” Macenić emphasizes. “They help in avoiding oversizing or undersizing of the ground heat exchanger field, leading to a more effective system.”
The results of the study are promising. The geothermal system can deliver 555.0 MWhth of heating energy annually, with a peak capacity of 370 kWth. In cooling mode, it can provide 344.0 MWhf of cooling energy, with a peak capacity of 438 kWf. The system operates in a bivalent mode, with dry coolers covering residual cooling needs. This approach ensures that the system can handle peak loads while maximizing the use of renewable energy.
The implications of this research are far-reaching. As the EU sets ambitious targets for reducing emissions from the energy sector by 2030, the use of energy piles could become a standard practice in building construction. This technology offers a sustainable and cost-effective solution for heating and cooling, reducing reliance on fossil fuels and lowering carbon emissions.
The case study, published in the journal Geosciences, highlights the potential of energy piles in large commercial buildings. As Marija Macenić and her team continue to explore this technology, the future of geothermal energy in the built environment looks increasingly bright. This project, the largest of its kind in Croatia and notable in the EU, sets a precedent for future developments in the field. By integrating renewable energy solutions into building design, the energy sector can move closer to achieving its sustainability goals. The study underscores the importance of innovative design and thorough testing in creating effective and efficient geothermal systems. As more buildings adopt this technology, the energy landscape could see a significant shift towards sustainability and efficiency.
