Lisø PhD Dissertation Manuscript - NTNU

Lisø, K.R./ Building envelope performance in harsh climates: Methods for geographically dependent design
1 Introduction
“We are venturing into the unknown with climate, and its associated impacts could be quite
disruptive” (Karl and Trenberth, 2003, p. 1719)
1.1 Principal objectives and scope
The principal objectives of the present work 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 building envelopes in relation to
external climatic impact. This is done through the development of approaches and
methods for assessing impacts of external climatic parameters, combining knowledge
on materials, structures and relevant climate data, applicable for both historical data
and regional scenarios for climate change. The results are intended to contribute to
more accurate building physics design guidelines and Codes of Practice, promoting
reliable and high-performance building envelopes in harsh climates.
The work is a first step towards methods and approaches allowing for geographically
dependent climate considerations to be made in the development of design guidelines
for high-performance building envelopes, and also approaches to assess the risks
associated with the future performance of building envelopes due to climate change.
The close interrelation between the two is to be clearly illustrated.
1.2 The climate of Norway
The climate of Norway is extremely varied, the rugged topography being one of the
main reasons for large local differences in temperatures, precipitation and wind
velocities over short distances. The seasonal variations are also extreme. January is
particularly eventful with frequent storms both in the mountains and along the coast.
February is statistically a much friendlier month. However, the greatest temperature
difference ever registered within a single month is from this month (location: Tynset,
Hedmark County, -43.5ºC on February 8 1985, +10.9ºC on February 26, i.e. a
temperature difference equal to 54.4ºC at the same station within the same month).
August is the month with most registrations of nights where the air temperature does
not fall below 20ºC, while September is one of the months with fewest extreme
weather events. October often represents a distinct transition in weather conditions,
with autumn storms along the coast of northern Norway and with the first snowfall in
the eastern parts of the country. The two last months of the year are statistically also
rather dramatic when it comes to both wind actions and all forms of precipitation.
The country’s long coastline and steep topography make it particularly likely to
experience extreme events like coastal storms, avalanches and landslides. From its
southernmost point (Lindesnes, see Figure 1) to its northernmost (North Cape) there
is a span of 13 degrees of latitude, or the same as from Lindesnes to the
Mediterranean Sea. There are also large variations in received solar energy during
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