The steady growth of solar thermal systems for more than three decades has shown that solar heating systems are both mature and technically reliable. However, they have usually been sold as an add-on to conventional hot water or space heating configurations. Looking towards the future, it appears a clear need of developing hybrid technologies that offer a complete heating/cooling system based on renewables, able to cover 100% of buildings’ demand. One very promising possibility is the combination of solar systems and ground-source heat pumps. At the same time, the new concept of LowEx Building Systems has been developed and strongly supports the intelligent integration of so called ‘low-value energy’ sources in buildings to meet their demand in a more efficient and sustainable way. With the aim of exploring more about this topic and show that LowEx Building Systems are a reality with many advantages when looking for a more energy-efficient and sustainable future, this master thesis has been carried out. The present work focuses on a specific case study, a single-family house in the Swiss city of Zurich. Its goal is to design and optimize the energy system able to meet space heating and cooling and domestic hot water demand of the mentioned dwelling. Taking into account the concept of LowEx in Building Systems and a fundamental knowledge in solar and geothermal resources, a system based on a hybrid ground source heat pump in combination with unglazed PVT collectors, connected with thermal storages, is designed. The system model is developed in TRNSYS environment, using TRNBuild for the simulation of a high insulated building and a first estimation of its thermal and electric loads. After validating and integrating the main components by means of an intelligent control, one-year dynamic simulations are performed for analysing its response in terms of energy supply and efficiency. Later on, new measures are adopted regarding load management and efficiency looking for its optimization. A study to check the effect of insulation on space conditioning demand and system performance has been also developed. Moreover, due to the recent interest in ground’s regeneration as a solution for minimizing ground-source systems impact, a study on ground’s temperature evolution over a period of 30 years for different cases is conducted. Finally, the influence of PVT collectors’ location to compare roof vs façade arrangements and determine a possible combined solution is included.