New ways towards increased efficiency in the utilization of energy flows in buildings

摘要

It is often claimed that energy is consumed; this is not only done in everyday conversation but also in scientific discussions associated with energy and environmental issues. This claim conflicts with the first law of thermodynamics stating that the total amount of energy is conserved, even though forms of energy may change from one to another. This is why we need to use the thermodynamic concept, exergy, to fully understand what is consumed. An optimization of the exergy flows in building, similar to other thermodynamic systems such as power stations, can help in identifying the potential of increased efficiency in energy utilization. This paper shows, through analyses and examples, that calculations based on the energy conservation and primary energy concept alone, are inadequate for gaining a full understanding of all important aspects of energy utilization processes.The high potential for a further increase in the efficiency of; for example, boilers, can not be quantified by energy analysis - the energy efficiency is close to 1; however, this potential can be showed by using exergy analysis. This research work is related to the international co-operation work in the IEA ECBCS Annex 37 "Low Exergy Systems for Heating and Cooling of Buildings".