Low Exergy Systems for High-Performance Buildings and Communities

There is an obvious and indisputable need for an increase in the efficiency of energyutilisation in buildings. Heating, cooling and lighting appliances in buildings account for morethan one third of the worlds primary energy demand. In turn, building stock is a majorcontributor to energy-related environmental problems. There are great potentials, which canbe obtained through a more efficient use of energy in buildings.An optimisation of the exergy flows in buildings and the related supply structures, similar toother thermodynamic systems such as power stations, can help in identifying the potential ofincreased efficiency in energy utilisation. Through analyses, it can be shown that calculationsbased on the energy conservation and primary energy concept alone are inadequate forgaining a full understanding of all important aspects of energy utilisation processes. The highpotential for a further increase in the efficiency of; for example, boilers, can not be quantifiedby energy analysis - the energy efficiency is close to 100%; however, this potential can beshowed by using exergy analysis [1], the exergy efficiency of a common gas boiler is about8%.This paper outlines the international co-operative work in the general framework of theInternational Energy Agency (IEA), the ECBCS Annex 49 Low Exergy Systems for HighPerformance Buildings and Communities [2].