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LowEx
The concept of exergy in energy economic analyses
Contact Lukas [email protected]
+43 1 58801 37351
EEG-Team Lukas Kranzl, Andreas Mller,Reinhard Haas
Client BMVIT
Coordination Fraunhofer Institute for BuildingPhysics
PartnersDuration 06/2008 10/2009
Website www.annex49.com
Core objectives use exergy analysis to develop tools,
guidelines, recommendations,and background material for designers
and decision makers in thefields of building, energy production and
politics
promote possible energy/exergy cost-efficient measures
forretrofit and new buildings
promote the exergy-related performance analysis of the
buildings,from the community level perspective
Core contents Exergy Analysis methodologiesExergy efficient
community supply systemsExergy efficient building
technologiesKnowledge transfer and dissemination
Project description
The exergy content required to satisfy the demands for the
heating and cooling ofbuildings is very low, since a room
temperature level of about 20C is very close to ambient
conditions. Nevertheless, high quality energy sources like
fossil fuels are commonly used tosatisfy these small demands for
exergy.The new approach is not necessarily focused on a further
reduction of the energy flowthrough a buildings envelope: when the
demands for heating and cooling have already been
minimised, the low-exergy approach aims at satisfying the
remaining thermal energydemand using only low quality energy.IEA
ECBCS Annex 49 (Low Exergy Systems for High Performance Buildings
andCommunities) aims at improving, both on a community and building
level, the design ofenergy use strategies which account for the
different qualities of energy sources, fromgeneration and
distribution to consumption within in the built environment.
Annex 49 is based on an integral approach which includes the
analysis and optimisation of
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the exergy demand in the heating and cooling systems as well as
in other processes whereenergy/exergy is used within the building
stock.
It is known that the total energy use caused by buildings
accounts for more than one third
of the worlds primary energy demand. There is, however, a
substantial saving potential inthe building stock. The
implementation of exergy analyses paves the way for
newopportunities to increase the overall efficiency of the energy
chain.
The method of exergy analyses has been found to provide the most
correct and insightfulassessment of the thermodynamic features of
any process and offers a clear, quantitative
indication of both the irreversibilities and the degree of
matching between the resourcesused and the end-use energy
flows.
Core tasks EEG
Analysis of cost efficiency of LowEx systems Exergetic analysis
of long-term scenarios in the Austrian space heating sector
Exergetic analysis of renewable energy systems (in particular
bioenergy, includingpolygeneration)
Moreover, EEG contributes to the following ascpects of annex 49:
system optimisation
strategies, best practice examples for buildings and communities
in Austria anddissemination activities.
Results
The tools, guidelines, recommendations, best-practice examples,
pre-normative proposalsand background material developed within the
framework of Annex 49 will be oriented andmade available to
designers, planners and decision makers in the fields of building,
energyproduction and politics. Using results from different
research projects of the participantcountries, a wide range of
cases will be studied. At the building level, both residential
and
commercial buildings will be taken into consideration.
At the community and supply level, the widest spectrum of
possibilities will be assessed. In
addition, several climatic conditions will be taken into
account.
