Low exergy systems for high-performance buildings and communities
ECBCS Annex 49, Annex 49 midterm report
The present reports aims at outlining mid-term research outcomes within the IEA ECBCS Annex 49 international research project. Firstly, an introduction into the use of the exergy concept for the particular case of buildings and building system`s analysis is given. Necessarily, the introduction begins with a definition of the environmental space for a system to be analysed, so-called "reference environment" in thermodynamics, which is of capital importance for exergy analysis. A brief discussion on the suitable reference environment for exergy analysis in buildings is also included. Furthermore, the importance of dynamic exergy analysis for buildings, particularly for the cooling case is highlighted, as well as the possibility and necessity of including indoor and outdoor air humidity in exergy assessments, particularly in the case of hot and humid climates. From a literature review on the use of the exergy concept for buildings and building systems, the great importance of a unitary and common analysis framework for exergy assessment has been derived and highlighted. This is one of the main aims and objectives of Annex 49 research activities. Following, the state of the art of the method for exergy analysis in buildings as derived and used within Annex 49 activities is presented. The method for buildings exergy analysis has been widened within Annex 49 research activities, so as to be applied to energy supply structures on a community scale. The state of the art of an excel tool for community exergy analysis, which will be one of the main outcomes from Annex 49, is also introduced. The insight on the development of the method for exergy analysis is complemented with the description of several case studies, both on a community and building level. These case studies are study objects of innovative building technologies or energy supply structures in whose design the exergy principles play a key role and where exergy analysis will be applied.
Fraunhofer-Institut für Bauphysik -IBP-, Stuttgart