Lisø PhD Dissertation Manuscript - NTNU

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<strong>Lisø</strong>, K.R./ Building envelope performance in harsh climates: Methods for geographically dependent design The building economics of climate change (Paper III) A way of analysing the building economics of climate change is proposed based on two approaches. Firstly it is the putty-clay approach to the theory of investment and production. The starting-point for this approach is that the scope for choosing different designs of a building is far broader before than after the building is erected. I.e. a building consists of elements that are costly to change once the building is erected, and of elements that are more easily maintained. The other pillar is the real options approach. This approach highlights the fact that information relevant for decision makers arrives over time. Immediate decisions should take into account that they affect possible future actions and their profitability. I.e. immediate decisions affect the value of real options. The potential benefits or adverse implications of climate change on the building stock can be addressed at different levels: How will the performance and cost of operating of existing buildings be affected, if the buildings characteristics are kept unaltered? How should existing buildings be adapted to changes in climatic impact? At what costs can this be done, and when should it be done? How will the technical and economic lifetime of buildings be influenced? How will the choice of technology, materials and design in new construction be affected? How will the time path of the level of new construction be affected? The analytical framework developed in Paper III is intended to be applicable at all these levels. The existing building stock will be less suitable than new buildings, under a new climate regime. Nevertheless, for the larger part of the building stock it will be profitable to continue the use. The economic lifetime of existing buildings will in part depend on their adaptability to changed climate conditions. Given the long lifetime of the building stock, the time before the whole building stock is optimally adapted to a new climate regime can amount to a hundred years or more. The building stock some time into the future consists of the building stock of today and of future new construction. Parts of the present building stock will in the future be adapted to externally imposed changes in the environment, while parts are kept as is. Analysis of how the building stock is affected by climate change should handle this diversity. This diversity should be treated within the framework of some kind of vintage model. Formulation of such a vintage model involves complex problems of aggregation. A central tool in this aggregation will be considerations of how the use value of different parts (or classes or vintages) of the existing building stock are expected to evolve over time as more reliable climate models are developed. The model describes important aspects of the building economics of climate change, and identifies stakeholders. It is a model of the decisions of a building owner facing an uncertain evolvement of the climate. The model shows that the decisions are affected by both the expected profitability of the different actions, and on the effects the actions have on the profitability of future choices. Hence, using a real option approach enhances the understanding of actions taken by owners of buildings. Some simple results are derived. Climate change can reduce both conversion activities (e.g. 14
<strong>Lisø</strong>, K.R./ Building envelope performance in harsh climates: Methods for geographically dependent design reconstruction or refurbishing) and the occurrence of scrapping of buildings. Hence, future climate uncertainty can in fact increase the economic lifetime of a building. Integrated approach to risk management of climate change impacts (Paper IV) Building standards, Codes of Practice, design guidelines and operational procedures are today based on historic weather data. The existing building stock is in the next decades likely to be exposed to significantly different climatic strains than they are today, due to climate change. This work discusses the use of modern risk management theories as a basis for the development of cross-disciplinary strategies to meet the challenges of future climate change within the built environment. First, climate vulnerability and adaptation is discussed in general. Next, a point of departure for the support of decision-making aimed at reducing climate vulnerability in the built environment is suggested, using established risk management strategies and Norway as starting point. Finally, possible ways of supporting decision-making aiming at ensuring sustainable buildings are suggested, applying a flexible combination of risk-based, precautionary and discursive risk management strategies. There are large uncertainties associated with the future performance of the built environment due to changes in external climatic impact. In order to develop adaptation strategies, one must find effective ways of strengthening institutional capacity. Cross-disciplinary risk-based management strategies, together with design guidelines that accounts for both historical local climatic conditions and potential future changes, can be an important step towards a more active and dynamic way of ensuring a high-quality construction process and a sustainable built environment in the light of the unknown risks of future climate change. For large, complex building projects there is an established tradition of using risk analysis methods. This tradition has not moved from large-scale to more “trivial” building. Obviously, there are benefits to be gained from the introduction of modern risk-based management strategies within a greater extent of the construction industry. Three different strategies (risk-based, precautionary and discursive strategies) are discussed. The choice of strategy is strongly dependent on the characteristics of the risk at hand. Facing the future risks of climate change, it is suggested that a flexible approach using a combination of these strategies can help reduce potential impacts. Reducing the potential for defects or damage through the development of technical and organizational preventive measures (a risk-based management strategy) while at the same time applying the precautionary principle and discursive strategies in the design, construction and geographical localization of buildings, is likely to increase the robustness of the built environment in light of the unknown risks of climate change. For the described integrated approach to risk management of future climate change impacts to be successful, it is necessary to ensure careful co-operation along vertical decision-making lines: i.e. from government regulatory bodies via local regulatory bodies and inhabitants, research communities and company management to the craftsmen on site. 15
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cost of repairing process-induced b
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change in quality (Mehus et al., 20
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on the impacts of different climati
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different strategies: risk-based, p
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Lisø, K.R./ Building envelope perf
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Learning from experience - an analy
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An important aspect of the programm
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Concrete walls 32 % LECA masonry 10
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construction industry, and academic
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BUILDING RESEARCH &INFORMATION (JAN
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greater variations (Lisø et al., 2
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Typical problem areas and recommend
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Figure 3b Recommended design of win
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Figure 7 Example showing the recomm
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Figure 11a Poor solution for a £as
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Acknowledgements This paper was wri
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Climate adapted design of masonry s
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2. Masonry defects in Norway 2.1. S
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Fig. 2. Example illustrations of th
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The presented results are in good a
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appropriate in a more severe type o
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screen in a two-stage weatherproofi
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INCREASED SNOW LOADS AND WIND ACTIO
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The hurricane (Beaufort number 12)
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The extensive revisions of the code
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The number of buildings investigate
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As is apparent from the values in t
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climate change is now dominated by
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TABLE 3. Summary of findings Struct
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Lisø, K.R./ Building envelope perf
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temperature of -4°C or less. See F
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Today, frost resistance of brick, c
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degree of saturation, freezing will
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accelerated frost damage or frost d
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A possible objection to the present
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[17] Dührkop H., Saretok V., Sneck
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Decay potential in wood structures
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Wood decaying fungi will only be ac
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to promote decay prevails. Two of t
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Acknowledgements This paper has bee
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(a driving rain gauge), however, is
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Fig. 1. Map of Norwayshowing the lo
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Frequency 25 20 15 10 5 0 highest p
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interesting to compare those result
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Effects of wind exposure on roof sn
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In ISO 4355 ”Bases for design of
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variety of roofs and wind exposures
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Li and Pomeroy [13] evaluated hourl
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Fig. 5. Exposure coefficients for 3
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meteorological stations are expecte
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Many of the meteorological stations
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the ground with return period of 30
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References [1] Standards Norway. De
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