Lisø PhD Dissertation Manuscript - NTNU

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766 Nordvik and Lisø The topic of this paper has not been much studied using tools from economic theory. Central issues for us are to survey the possible impacts of climate change on the building stock and the behaviour of building owners. Hence, as the title indicates, the paper is a primer on the building economics of climate change rather than providing final empirical answers. Furthermore, we have focused on the microeconomics of impact on and adaptation of single buildings. Aggregation will be treated at a later stage. At the outset, we will stress that even though the paper is purely theoretical, it has an empirical ambition. Analysing the building economics of climate change Climate vulnerability in general 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 (Camilleri et al., 2001). The study concludes 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. Climate vulnerability in a Norwegian context Norway can be considered a highly exposed country due to its extreme weather conditions (O’Brien et al., 2003). The country’s long coastline and steep topography make it particularly prone to extreme events like coastal storms, avalanches and landslides. In addition, Norway may be exposed to changes in autumn rainfall, and to an increase in the frequency and intensity of storms due to global warming. While the full range of impacts resulting from these changes remains uncertain, it is becoming clear that adaptation to climate change is necessary and inevitable. Adaptation to the prevailing climatic conditions has always been crucial for the viability of Norwegian society, but future climate changes may expose Norway to new challenges (Lisø et al., 2003a). 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 velocity values. For rendered walls, the duration of rainy periods might be of greater importance than the maximum intensity of precipitation that occurs in the form of lashing rain. For board-clad walls, the intensity of driving rain may be the most important. 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 (Lisø et al., 2003b). 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 climatic-related impacts that buildings will have to endure. Buildings and potential impacts of climate change Several sources of uncertainty exist related to both scenarios for global climate change, and to the effects of global warming on regional-level climate. The regional scenarios, therefore, should not be considered as forecasts in an absolute sense, but they do offer insights into likely range and nature of future weather scenarios (Lisø et al., 2003a). The climatic impact that a single building is exposed to over a limited period of time can be described as a stochastic process. The less than perfectly known regional climate development under global warming can consequently be described as a stochastic process that selects among climate generated processes, or climate change scenarios. The perceived characteristics of this climate-generating process can change over time, i.e. the different actors in the construction industry and in the real estate market are assumed to be able to learn. Scenarios for future climate change at the very local level are highly uncertain. However, buildings are located and they are affected by weather related strains. Owners will consequently have to adapt to the expected climatic environment at the very place where the building is located.
Building economics of climate change Introducing the analytical framework The potential 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 by climate change, if the buildings characteristics are kept unaltered? • How should existing buildings be adapted to changes in the stream of weather related strains that hits the building enclosure. At what cost can this be done for, and when should it be done? • How will the technical lifetime of buildings be affected by climate change? What about the economic lifetime? • 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 this paper is, in principle, intended to be applicable at all these levels. In fact, we will claim that these levels are nested within each other. In order to illustrate the importance of the abovementioned issues, think about the distinction between a long-run and a short-run equilibrium in the property market. Assume that we experience a (perfectly observed) shift from one ‘stable’ climate regime to another ‘stable’ climate regime. This changes the optimal design of buildings. However, one does not start from scratch. When the shift is experienced, a building stock already exists. The existing building stock will be less suitable than newly constructed buildings under the 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 durability 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. Hence, John Maynard Keynes’ famous remark – ‘In the long run, gentlemen, we are all dead’ – really applies to the process of adjustment towards a new long run equilibrium building stock, following a potentially more severe climate. An analysis of the building economics of climate change should, consequently, not confine itself to addressing the questions of how new buildings are and ought to be affected. On the other hand, the analysis should not be confined to investigations of how the existing building stock, without any adaptations taking place, is affected by changed occurrence of climate related strains. An economic analysis, of course, should address the question of how choices are affected by 767 changes in the framework under which decisions are taken and by initial endowments. Changes in the climate system are part of ‘the framework under which decisions are taken’ and the existing building stock is part of ‘the initial endowments’. A building is a very ‘long lasting’ durable asset that over time is changed due to exogenously imposed strains and by actions taken by different stakeholders. Analysis of how buildings will be affected by climate change should consequently be done within a dynamic analytical framework that explicitly allows for changes in the information sets over time. The analysis should result in descriptions of the expected time paths of the state of the building stock and of measures taken to adapt. The building stock some time into the future consists of the building stock of today and of the new construction of the future. Parts of the present building stock will in the future be adapted to changes in the environment, while some parts will be kept as they are. Analysis of how the building stock is affected by climate change should handle this diversity. We propose that this diversity should be treated within the framework of some kind of vintage model. Formulation of such a vintage model involves complex problems of (non-trivial) aggregation. A central tool in this aggregation will be considerations of how the value in use of different parts (or classes or vintages) of the existing building stock are expected to evolve over time as improved and more reliable climate change scenarios are developed. Before the questions of aggregation, or formulation of vintage models, are addressed one should concentrate upon how the potential impacts on single buildings should be identified. In other words, before aggregation is treated we need to focus on the mechanisms that are to be aggregated. The putty-clay and the real option approaches The paper proposes a way of analysing the building economics of climate change that is based on two pillars or approaches. Firstly, it is the putty-clay approach to the theory of investment and production. The main starting-point for this is that the scope for choosing different designs of a building is far broader before than after the building is erected. Hence, a building consists of elements that are costly to change once the building is erected, and of elements that can be more easily maintained. The putty-clay approach dates back to Johansen (1959). The other pillar of our analysis is the real option approach. In short, one can say that this approach highlights the fact that information relevant for decision makers arrives over time. Immediate decisions should take into account that they affect possible actions taken
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Building envelope performance asses
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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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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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