Low exergy systems for high-performance buildings and communities

There is an obvious and indisputable need for an increase in the efficiency of energy utilisation in buildings. Heating, cooling and lighting appliances in buildings account for more than one third of the world's primary energy demand. In turn, building stock is a major contributor to energy-related environmental problems. There are great potentials, which can be obtained through a more efficient use of energy in buildings. An optimisation of the exergy flows in buildings and the related supply structures, similar to other thermodynamic systems such as power stations, can help in identifying the potential of increased efficiency in energy utilisation. Through analyses, it can be shown 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 utilisation 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 100%; however, this potential can be showed by using exergy analysis [1], the exergy efficiency of a common gas boiler is about 8%. This paper outlines the international co-operative work in the general framework of the International Energy Agency (IEA), the ECBCS Annex 49 "Low Exergy Systems for High Performance Buildings and Communities" [2].