In this study, a modeling methodology is presented for evaluating the performance of a hybrid system integrating different types of solar collectors, namely photovoltaic (PV), glazed flat plate solar thermal (ST) and unglazed photovoltaic-thermal (PVT) collectors to harvest solar energy. Further, the system is integrated with a seasonal storage that is an aquifer thermal energy storage (ATES) system, a heat exchanger and a heat pump (HP) to provide heating, including space heating (SH), domestic hot water (DHW), as well as cooling. The investigation considers various operational modes depending on the climate conditions and building characteristics. The study focuses on comparison of solar collectors in realistic scenarios, examining heating type and insulation levels. Real energy consumption data considering five residential buildings in Amsterdam is employed for the analysis. Annual simulations for the considered buildings are conducted for SH and DHW coverage, along with cooling. The results indicate that ATES combined with glazed ST collectors demonstrates superior heat storage while HP with PV/ST combination and floor heating achieves an average coefficient of performance (COP) of 6.09 for both SH and DHW. In contrast, HP combined with PVTs shows the lowest performance, with a COP of around 5 when used with radiator heating. Additionally, majority of the demand is covered using HP storage mode with seasonal storage and HP while building insulation plays a crucial role.

Positive Energy Districts (PEDs) are integral to achieving sustainable urban development by enhancing energy self-sufficiency and reducing carbon emissions. This paper explores energy balance calculations in four diverse case study districts within different climatic conditions—Fiat Village in Settimo Torinese (Italy), Großschönau (Austria), Beursplain in Amsterdam (Netherlands), and Lunca Pomostului in Reşiţa (Romania)—as part of the SIMPLY Positive project. Each district faces unique challenges, such as outdated infrastructure or heritage protection, which we address through tailored strategies including building renovations and the integration of renewable energy systems. Additionally, we employ advanced simulation methodologies to assess energy performance. Simulation results highlight the significance of innovative technologies like photovoltaic-thermal (PVT) systems, application of demand-side actions, and flexible grid usage. Furthermore, mobility assessments and resident-driven initiatives demonstrate the critical role of community engagement in reducing carbon footprints. This study underscores the adaptability of PED frameworks across varied urban contexts and provides actionable insights for scaling similar strategies globally, supporting net-zero energy targets.

This paper presents dynamic air-based models of a hybrid photovoltaic-thermal (PVT) collector. The models are developed with the aim of estimating the temperature of the collector components and therefore of estimating the annual generation of electrical energy and thermal energy outputs, by using actual climate data of six different cities based on Köppen-Geiger-Photovoltaic (KGPV) climate zones. The results show that the unglazed type collector has the best PV cooling while the dual channel collector has the best air heating among air-based PVT collectors. The results also indicate that the use of additional fluid enhances both electrical and thermal performance. The dynamic models are validated by comparison with results found in the literature. The paper also discusses a novel bi-fluid PVT system combined with a storage tank and an H-infinity based robust controller that can handle uncertainties. The results of the bi-fluid system show that the fraction of energy demand covered by the system is highly dependent on climate conditions and the collector's surface area. It was found that for a small-scale house (standard for four people), the proposed system can cover more than 70% annual domestic hot water demand for cities with high solar irradiance and 32% for a city with low solar irradiance.