Lisø PhD Dissertation Manuscript - NTNU

More documents

Recommendations

Info

<strong>Lisø</strong>, K.R./ Building envelope performance in harsh climates: Methods for geographically dependent design Norway, one of the wealthiest countries in the world, is normally considered to be resilient to the impacts of climate change, but vulnerability varies considerably across scale (O’Brien et al., 2004). The lifetime of buildings and other infrastructure depends on the harshness of local weather conditions. The regional scenarios developed by climate scientists for climate change as a result of global warming must therefore be used as a basis for studies of the possible technological, economic and social impacts of such change. 1.5 Climate adaptation and building defects The historical development of the Norwegian building stock and building traditions implies both an adaptation towards different preconditions for use of buildings and varying styles of architecture, but also an adjustment towards the extreme climatic variations throughout the country. Changes in building practice also reflect the economic development and new trends and requirements in standard of living. Wood is, due to easy access, the most common building material. As of January 2006 a total of 3,722,012 buildings are registered in Norway. 1,413,516 of these are residential buildings, and there 2,308,482 non-residential buildings (see Table 1 in Paper V for a distribution of residential buildings by building type and County). Today approximately eight out of ten people live in urban areas compared to 50 per cent after World War II. Figure 2 provides a population density distribution for the country. In Norway as a whole there are more than 900 urban settlements (a collection of houses is described as an urban settlement if at least 200 people live there and the distance between houses is less than 50 metres). Compared to other European countries, Norwegians more often live in detached houses or other small dwelling houses, which they own. While eight out of ten Norwegian households live in houses that they own, this applies to only four out of ten German households (source: Statistics Norway, www.ssb.no). Natural disasters caused by extreme weather events are one of the major challenges confronting the built environment. However, the amount of building defects not covered by natural disaster insurance is also tremendous. Investigations carried out by SINTEF Building and Infrastructure indicates that the cost of repairing process induced building defects in Norway amounts to 5% of the annual capital invested in new buildings. Correcting faults and repairing defects in buildings during the construction process is estimated to cost roughly the same amount as repairing buildings in use, e.g. another 5% (Ingvaldsen, 1994). With an annual investment in refurbishment and new construction of 16.5 billion euro (as in 2003), it is reasonable to estimate that approximately 1.65 billion euro is being spent on repairing defects or damage to buildings every year (provided that Ingvaldsens 1994-estimate is still valid). Defects related to the building envelope constitute 66% of the process induced building defects investigated by the institute in the 10-year period 1993-2002 (Paper V). A bulk of the defects (76%) is related to moisture as the main source causing defects. This experience-based knowledge provides valuable insight on the vulnerability of the building stock, as it shed light on the underlying causes of defects and enables assessment of preventive actions. 6
<strong>Lisø</strong>, K.R./ Building envelope performance in harsh climates: Methods for geographically dependent design Figure 2. Population density in Norway (as of January 1 2002). From Statistics Norway, www.ssb.no. The increasing demands in the construction industry for profit and shorter construction periods, combined with extremely varied climatic impacts during the construction process, also prove to be a difficult circle to square. The increasing number of extreme weather events reminds us of how vulnerable society is when faced with major climatic variations and severe weather. Projected changes in climatic conditions due to global warming will further enhance vulnerability within the construction industry. The most influential government regulatory measure to ensure adherence to building codes and standards is the Technical Regulations under the Norwegian Planning and Building Act (PBA), which since 1997 have been performance-based. The principal motive for a transition from a prescriptive-based code to a performance-based code in Norway has been to stimulate to an increase in the quality of buildings and a reduction of the amount of building defects. The transition has been a gradual process, and the performance-based way of thinking was introduced in Norwegian building regulations as early as 1969 (Norwegian Building Research Institute, 2003). The former Norwegian Building Research Institute (now part of SINTEF) had developed a basis for performance requirements for different building technology solutions. The institute were advocating the necessity of first defining the function of different building structures and elements, and then determine the performance requirements in accordance with the functional demands they were to fulfil. The following example illustrates the distinction between prescriptive-based codes and performance-based codes: Prescriptive codes or guidelines declare how e.g. a wall is designed and constructed, but do not define the performance in use. Performancebased codes and guidelines, on the other hand, do define the performance 7
Page 1 and 2: Building envelope performance asses
Page 3 and 4: Lisø, K.R./ Building envelope perf
Page 15: Lisø, K.R./ Building envelope perf
Page 41 and 42: BUILDING RESEARCH &INFORMATION (200
Page 43 and 44: LisÖ et al. on how to cope with an
Page 45 and 46: LisÖ et al. the exposure to contin
Page 47 and 48: LisÖ et al. business premises. The
Page 49 and 50: LisÖ et al. construction industry
Page 51 and 52: Research in Building Physics, Carme
Page 53 and 54: 4 CLIMATE CHANGE SCENARIOS FOR NORW
Page 55 and 56: with large amounts of precipitation
Page 57 and 58: will most likely be worse, even wit
Page 59: Graves, H.M. & Phillipson, M.C. 200
Page 62 and 63: 766 Nordvik and Lisø The topic of
Page 64 and 65: 768 Nordvik and Lisø into the futu
Page 66 and 67:
770 Nordvik and Lisø climate chang
Page 68 and 69:
772 Nordvik and Lisø 0 Â Â = p d
Page 70 and 71:
774 Nordvik and Lisø probably to a
Page 73 and 74:
BUILDING RESEARCH &INFORMATION (200
Page 75 and 76:
cost of repairing process-induced b
Page 77 and 78:
change in quality (Mehus et al., 20
Page 79 and 80:
on the impacts of different climati
Page 81 and 82:
different strategies: risk-based, p
Page 83 and 84:
Lisø, K.R./ Building envelope perf
Page 85 and 86:
Learning from experience - an analy
Page 87 and 88:
An important aspect of the programm
Page 89 and 90:
Concrete walls 32 % LECA masonry 10
Page 91 and 92:
construction industry, and academic
Page 93 and 94:
BUILDING RESEARCH &INFORMATION (JAN
Page 95 and 96:
greater variations (Lisø et al., 2
Page 97 and 98:
Typical problem areas and recommend
Page 99 and 100:
Figure 3b Recommended design of win
Page 101 and 102:
Figure 7 Example showing the recomm
Page 103 and 104:
Figure 11a Poor solution for a £as
Page 105 and 106:
Acknowledgements This paper was wri
Page 107 and 108:
Climate adapted design of masonry s
Page 109 and 110:
2. Masonry defects in Norway 2.1. S
Page 111 and 112:
Fig. 2. Example illustrations of th
Page 113 and 114:
The presented results are in good a
Page 115 and 116:
appropriate in a more severe type o
Page 117 and 118:
screen in a two-stage weatherproofi
Page 119 and 120:
INCREASED SNOW LOADS AND WIND ACTIO
Page 121 and 122:
The hurricane (Beaufort number 12)
Page 123 and 124:
The extensive revisions of the code
Page 125 and 126:
The number of buildings investigate
Page 127 and 128:
As is apparent from the values in t
Page 129 and 130:
climate change is now dominated by
Page 131:
TABLE 3. Summary of findings Struct
Page 134 and 135:
Lisø, K.R./ Building envelope perf
Page 136 and 137:
temperature of -4°C or less. See F
Page 138 and 139:
Today, frost resistance of brick, c
Page 140 and 141:
degree of saturation, freezing will
Page 142 and 143:
accelerated frost damage or frost d
Page 144 and 145:
A possible objection to the present
Page 146 and 147:
[17] Dührkop H., Saretok V., Sneck
Page 149 and 150:
Decay potential in wood structures
Page 151 and 152:
Wood decaying fungi will only be ac
Page 153 and 154:
to promote decay prevails. Two of t
Page 155:
Acknowledgements This paper has bee
Page 158 and 159:
(a driving rain gauge), however, is
Page 160 and 161:
Fig. 1. Map of Norwayshowing the lo
Page 162 and 163:
Frequency 25 20 15 10 5 0 highest p
Page 164 and 165:
interesting to compare those result
Page 167 and 168:
Effects of wind exposure on roof sn
Page 169 and 170:
In ISO 4355 ”Bases for design of
Page 171 and 172:
variety of roofs and wind exposures
Page 173 and 174:
Li and Pomeroy [13] evaluated hourl
Page 175 and 176:
Fig. 5. Exposure coefficients for 3
Page 177 and 178:
meteorological stations are expecte
Page 179 and 180:
Many of the meteorological stations
Page 181 and 182:
the ground with return period of 30
Page 183:
References [1] Standards Norway. De
show all

Lisø PhD Dissertation Manuscript - NTNU

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?