Lisø PhD Dissertation Manuscript - NTNU

Lisø, K.R./ Building envelope performance in harsh climates: Methods for geographically dependent design
Summary
The lifetime of the built environment depends strongly on the severity of local
climatic conditions. A well-functioning and reliable infrastructure is a precondition
for economic growth and social development. The climate and topography of
Norway puts great demands on the design and localization of buildings. The
relationship between materials, structures and climatic impact is highly complex;
illustrating the need for new and improved methods for vulnerability assessment of
building envelope performance in relation to externally imposed climatic strains.
Historically, major variations in climatic impact have led to corresponding large
variations in building practice throughout the country - often well suited to local
conditions. Today it is fair to say that sound building traditions and practice to some
extent are being rejected in the quest for cost-effective solutions. Furthermore,
projected changes in climatic conditions due to global warming will enhance the
vulnerability within the built environment.
The primary objectives of the present dissertation are to increase the knowledge
about possible impacts of climate change on building envelope performance, and to
analyse and update methods for the planning and design of external envelopes in
relation to climatic impact. This is accomplished through the development of
integrated approaches and improved methods for assessing impacts of external
climatic parameters on building envelopes, combining knowledge on materials,
structures and relevant climate data, applicable for both historical data and scenarios
for climate change. The results will contribute to more accurate building physics
design guidelines, promoting high-performance building envelopes in harsh climates.
Approaches to assessments of the risks associated with climate change and buildings
are suggested, identifying main areas of vulnerability in the construction industry. It
is shown that there are benefits to be gained from the introduction of risk
management strategies within a greater extent of the construction industry. A way of
analysing the building economics of climate change is also proposed
Analyses of building defects are necessary in order to further develop tools, solutions
and preventive measures ensuring high-performance building envelopes. To
illuminate the vulnerability of different building envelope elements under varying
climatic exposure, a comprehensive analysis of empirical data gathered from process
induced building defect assignments is carried out. The amount of building defects in
Norway clearly illustrates that it is not only the extreme weather events that need to
be studied as a foundation for adaptation towards a changing climate. Furthermore,
the analyses of defects reveal a fundamental need for climate differentiated design
guidelines.
New and improved methods for geographically dependent design of building
envelopes are proposed:
A method for assessing the relative potential of frost decay or frost damage of
porous, mineral building materials exposed to a given climate is developed.
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