New technologies for energy savings in the refurbishment of existing buildings.

The building sector is responsible for many environmental problems mainly because of the energy consumptions for heating, cooling, lighting, .... during the whole life cycle of a building. The refurbishment of the existing building stock offers an opportunity to take effective and environmentally friendly solutions. A thermal energy storage system is very effective item to reduce the energy consumptions because it allows the possibility of using solar energy continuously, reducing the internal temperature fluctuation and improving the thermal comfort. The most used heat storage materials for building application are the Phase Change Materials (PCMs) which store solar energy during the day and release it during the night. The aim of this work is to test the usefulness of PCMs for improving summer thermal comfort in lightweight buildings. In order to evaluate the performance of PCMs we carried out simulations using EnergyPlus, a building simulation tool based on the finite difference method. For the assessment of the optimal thermal comfort conditions we considered the adaptive comfort method and we introduced some new thermal comfort indicators. The results of simulations show a very significant effect of PCMs during the summer season. In particular the application of a PCM panel with a ventilated air gap proves to be beneficial for the indoor thermal comfort, due to a consistent decrease of the air temperature fluctuations and the reduction of the maximum operative temperature without using any cooling system. The present work is intended to give a contribution to optimize building components incorporating PCMs for thermal storage, in an energy savings and thermal comfort perspective.