Improved thermal energy storage for nearly zero energy buildings with PCM integration

Prudent and efficient utilization of renewable energy sources is needed in order to achieve clean energy transition. Since energy use in buildings represents around 40% of total energy use in European Union the reduction of energy use in this sector is most definitely needed. One of the great challenges in this sector represents retrofit of residential buildings where 3/4 of buildings in Europe are residential. To reduce energy consumption and increase the use of renewables in existing residential buildings to achieve nearly zero energy buildings (nZEB) a holistic approach of retrofit with interconnected technological system is needed. In the first part of this paper the nZEB and thermal energy storage are introduced for further implementation of the phase change material (PCM) into storage tank. Furthermore energy toolkit based on the synergetic interaction between technologies integrated in the system for holistic retrofit of residential buildings, which is under development within HEART project (HORIZON 2020), is presented. In this project step towards self-sufficient heating and cooling of building is made with increase in on-site consumption of self-produced energy from solar energy and interconnection between PV, electrical storage, heat pump, thermal energy storage, fan coil heat pump, cloud based decision support and building energy management system. With such a smart energy system the almost zero-energy buildings will be possible to decrease energy use in residential sector. Improvement of sensible thermal energy storage with implemented cylindrical modules filled with PCM is investigated experimentally. The results from experiment show that thermal energy storage unit with integrated modules filled with PCM can supply desired level of water temperature for longer period of time. The advantage of PCM in thermal energy storage is in applications that needs narrow temperature range of supplying and storing thermal energy what is the subject matter of consideration in the case of HEART project.