Processes in buildings: an exergetic analysis and potential for improving

The quality of a certain amount of energy is defined as the relative exergy content of this energy. Most of our buildings with their heating and cooling systems today are built for conversion of high quality energy sources to low quality use with destruction of the available exergy as a result. Globally we have a huge potential for transforming our processes to more efficient use of the exergy and also for feeding our processes directly from renewable energy sources without the use of high quality energy sources. Exergy analysis is also important as an innovation driver in buildings and building systems The work is carried out within the frame of IEA Annex 49 - Low Exergy Systems for High-Performance Buildings and Communities. The scope of the annex is to improve, on a community and building level, the design of energy use strategies, taking into account the different qualities of energy sources, from generation and distribution to consumption within in the built environment. In particular, this is carried our by the method of exergy analyses to provide assessment of the thermodynamic features of any process and to achieve a clear, quantitative indication of both the irreversibilities and potential for matchmaking between the resources used and the end-use energy flows. The paper contains a systematic survey of the exergy consuming processes for building and building appliances, their role in exergy balance, the level of energy quality needed in primary process and the potential for developing processes towards improved exergy efficiency. The work presented here gives a listing of the important processes in buildings with a discussion of their nature from an exergy point of view. The methodology for analysis is exemplified for a limited number of processes, dealing with the energy use and exergy destruction in processes, the potential for exergy saving and the discussion on the technical and economical feasibility.Presenters: name: Marco Molinari affiliation: (KTH - Royal Institute of Technology) email: marco@byv.kth.s