Abstract
A more efficient use of energy in the built environment is absolutely necessary. Using the exergy concept delivers more complete information on the use of the energy flows within buildings and opens up room for further improvements within the field. The aim of this study is to gain deeper insight into how the energy is being used in two already efficient building systems, namely a balanced ventilation system with heat recovery and a solar thermal system for space heating supply. Furthermore, desirable optimization chances for them will be pinpointed. The results of energy and exergy analyses of a first study on a typical building with both systems are compared. Annual dynamic simulations were carried out for the space heating case. Another major aim of the present study is to show the key differences between energy and exergy analyses of energy systems in buildings.