RES4BUILD project partners NCSR Demokritos have just published another paper.

Marika Pilou, George Kosmadakis, George Meramveliotakis, Achileas Krikas (2022) Towards a 100% renewable energy share for heating and cooling in office buildings with solar and geothermal energy, Solar Energy Advances, Volume 2,100020, ISSN 2667-1131,

Abstract: An integrated energy system for office buildings is examined, with the use of a numerical tool that has been developed for simulating renewable energy-based systems based on geothermal and solar energy. The main system components are the PV-Thermal (PVT) collectors, several boreholes that form a ground heat exchanger system and a multi-source heat pump supplied by heat either from the ambient air or water. The developed code in Python is used for the detailed investigation of the system performance over time, components’ sizing, as well as for analyzing various layouts. Different demand profiles have been considered according to the insulation level of the building, and the total PVT collector surface is varied from about 50 to 100 m². Focus is given here on the renewable energy share of the energy system for covering the heating and cooling demand of a typical office building in a warm climate (Athens, Greece) and in a cold one (Copenhagen, Denmark). Technical and environmental indicators are presented and compared with standard solutions. The results show that the heat pump can operate few moments during the day to charge the buffer tank, introducing high flexibility. Moreover, the annual COP in winter is over 4 in Athens and about 3.8 in Copenhagen. Self-consumption exceeds 30% in some cases in Athens, whereas is up to 11% in Copenhagen. Finally, considering rooftop limitations it is possible to reach 82% and 61% renewable share by adding standard PV panels in office buildings with moderate energy efficiency level in Athens and Copenhagen, respectively.

Keywords: PVT collectors; Heat pump; Borehole thermal energy storage; Office building; Heating and cooling

The publication is available online here: and can also be viewed on the project's Zenodo page: For other publications and project outputs please visit the results page.

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