Lisø PhD Dissertation Manuscript - NTNU

...the widespread building that has taken place
on river flood plains across central Europe in
recent years [that] is to blame for why the intense
rainfall had such a catastrophic effect.
(p. 4)
The regular insurance claims related to floods, as well
as the intermittent large-scale destructions caused by
floods, such as the 1995 floods in the south-eastern
parts of the country, make land management a pertinent
issue also in Norway.
While few studies have focused on the possible impacts
of climate change on the built environment in Norway,
impact studies in other countries show how vulnerable
society becomes in the face of major climatic events
and severe weather conditions. A British study
(Graves and Phillipson, 2000) shows that an increase
in wind speeds of 6% is likely to cause damage to
1 million buildings at a cost of £1–2 billion. The study
also addressed the major impacts of increased driving
rain quantities on the suitability of different types of
building enclosures, and the likely increase of maintenance
costs due to more extreme weather in parts of
England. Dry summers in the south of England could
lead to a 50–100% increase in subsidence claims in
vulnerable areas.
A study published by the Building Research
Association of New Zealand highlights climate change
impacts on building performance in New Zealand
(Camilleri et al., 2001). It was concluded that
the future performance of buildings in New Zealand
may be significantly altered with regard to coastal
and inland flooding, overheating, and wind damage
and flooding associated with tropical cyclones.
The hurricane that hit Northwest Norway on 1
January 1992 caused severe damage to buildings.
Large snow loads on roofs during the winter of
1999/2000 contributed to the collapse of several buildings
in northern Norway. The roof structures of several
buildings in parts of the country are thought to be far
below current design standards and may be in danger
of collapsing in the event of future heavy falls of snow.
Eastern Norway and the southern coastal regions
experienced extended periods of rainfall in the autumn
of 2000. The heavy rainfall caused damage to buildings
that had not previously been subjected to such
damage.
Although neither of the above-mentioned weather
events alone could be directly ascribed to climate
change, events of that character are expected to
increase in frequency under climate change. Extreme
weather conditions are familiar to Norwegian society.
However, there is a clear need to identify areas of vulnerability
in the construction industry with regard to
Norway’s built environment
the potential impacts of climate change, and to develop
and prioritise appropriate adaptation strategies.
Extensive degradation and damage to the built environment
occur every year due to the impacts of precipitation,
wind, temperature and exposure to the sun
causes. An understanding of how degradation and
damage can best be reduced is of significant importance
to the design and construction of buildings.
Future building materials, structures and building
enclosures will likely need to withstand even greater
climatic impact in parts of Norway than they do today.
When designing building enclosures to resist wind
actions, extremes are much more important than mean
wind velocities. For certain types of house facings (e.g.
rendered walls), the duration of rainy periods might be
of greater importance than the maximum intensity of
precipitation that occurs in the form of driving rain
(combined rain and wind). For other types of external
walls (e.g. board-clad walls), the intensity of driving
rain may be the most important factor. The total number
of freezing and thawing cycles is significant when
the whole-life performance of masonry constructions
is to be determined. For polymer materials, the sum
of ultraviolet radiation may determine the lifetime of
the products rather than the yearly averages in temperature.
Many parts of buildings’ external enclosures
are likely to be subject to faster degradation in parts
of the country where there is increased ultraviolet
radiation.
The above examples illustrate the complex relationship
between building materials, structures and climatic
impact, and they also shed light on the need for more
advanced and accurate methods of assessing building
performance in relation to climatic impacts. The prospect
of an even harsher climate in parts of the country
means that we must pay more attention to the design,
construction and geographical location of the built
environment, and be more cognisant of the climaticrelated
impacts that buildings will have to endure.
Hence, there is a clear need to develop further our
knowledge, methods, tools and solutions in particular
with respect to the planning and design of buildings
in severe climates in order to ensure a reliable building
stock in the future.
Adaptation strategies
Factors a¡ecting adaptation options and capacity
The distribution of risk in society and people’s control
over their environment are related to the underlying
economic and social situation (Adger, 1996). To
understand the vulnerability of a particular society,
sector or social group, it is necessary to analyse the factors
and processes that determine why some people or
businesses can cope, such as with damages caused by a
cyclone, and others cannot. The built environment
encompasses both domestic housing, industry and
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