Thermally activated heat storage structures combined with a heat pump for the use in low energy buildings

The building operating cost depends mainly on the quality of the building envelope and efficiency of systems for heating, cooling and domestic hot water. The big challenge for buildings with almost zero energy consumption is the use of renewable energy sources. The potential of renewable energy sources use for heating or cooling of buildings increases with the possibility to store heat or cold when they are available. Typical technologies utilize sensible heat storage technique, where the heat storage capacity depends mainly on the volume of medium and temperature differences. The capacity of storage medium, e. g. building structure, can be significantly increased by the use of proper kind of encapsulated Phase Change Materials (PCMs) for latent heat storage. Currently, the experiments carried out at Brno University of Technology are focused on latent heat storage technologies for proposed use in low-temperature heating or radiant cooling for residential and office buildings. The developed system uses air-water heat pump combined with sensible heat storage in storage tank and latent heat storage directly in building structures with integrated microencapsulated PCMs. Heating and cooling system consists of thermally activated floor, walls and ceiling structures. This system works with low temperature gradients in comparison with typical system based on the radiators situated bellow windows. The energy consumption and ability to fulfill the requirements on the quality of indoor environment of system described above are continuously observed and evaluated. Floor structure and plasterboards fixed on the ceiling and walls are thermally activated by capillary tubes. Water is used as a heat carrier medium. The floor slab and the plasterboards consist of 30 wt.% of microencapsulated organic Phase Change Materials. The paper shows results from measurement in summer and winter period in special twin rooms and shows contribution of the system to reduction of operating cost of building.