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BBR-Online-Publikation 10/08, Eds.: BMVBS/BBR, April 2008
Institut Wohnen und Umwelt, Darmstadt (contractor)
Peter Werner (project leader)
Elke Chmella-Emrich (architect), Kaiserslautern
Federal Office for Building and Regional Planning, Bonn
Andrea Vilz email@example.com
Germany is characterised by diverse climates and local conditions, and these conditions will alter as a result of climate change, which can no longer be reversed. The national adaptation strategy is trying to respond to this challenge. In the process, it has emerged that Germany’s adaptation strategies and precautionary measures for reducing negative consequences of climate change in the field of the construction of buildings, as yet, hardly got off the ground. The study attempts to give an initial overview of the level of knowledge and demand for adaptation strategies in field of construction. For the preparing of the survey national and international studies were analyzed as well as systematic enquiries on the Internet were conducted and numerous interviews were carried out with specialist persons, like building physicists, architects, planners, engineers, structural engineers, trained building workers, insurances, building material manufacturers and representatives of corresponding associations. If climate factors change significantly during the life cycle of a building, the building becomes less fit for its purpose, which is namely to protect people and provide a pleasant indoor environment. Building elements above ground, building elements in the ground and the technical building services must be adapted accordingly. The varying climate factors put particular stress on the outer shell of the building.
Construction planning, technique and execution are held to a high standard in Germany, and are designed to withstand the most varied climate exposure conditions. Many effects of both current and impending climate change on the building sector can be overcome within this standard. However, there is still a need for adjustment, in particular with regard to the increase in climatic incidents that are still considered "extreme events". These events, which are considered exceptional today but will probably become regular occurrences in the future, include distinct summer heat waves, heavy precipitation during the latter half of the year, an increase in winter storms and both accompanied by extreme driving rain, hail and unusually strong wind squalls.
Against the background of current climate forecasts, the problems are assessed as follows in a preliminary evaluation. The problem of increasing heat waves is considered to be a significant one, since it can have serious and damaging effects on health and well-being. The heat wave of 2003 was a clear example. The problem of increasing heavy rainfall and its potential effects on the outer shell of buildings as well as on building elements in the ground was also classed as high. The effects of changes in wind patterns (e.g. increasing winter storms), hail-storms or changes in the ground water balance are likewise assessed as significant problems for individual regions or locations. The increase in wet winters may have a significant negative impact on historic structures (examples of this phenomenon can be seen in England) or, under some circumstances, on wooden building elements. It has not yet been possible to evaluate this in more detail, however. One specific problem is the development in snow loads. Certain regions may experience levels of snowfall that have become unusual in recent times. Potential effects of more intense solar radiation during the summer on building elements and their material durability have been deemed less significant.
The study specifies various possible actions to combat the individual problem areas. The fundamental ones are as follows: providing that good heat insulation is ensured, shadow elements are incorporated in planning, building layouts are modified where necessary, solid building elements or storage mass are used, internal heat sources are reduced and the use of large glass areas is well thought out, problems of over-heating in buildings will be largely avoided, and air conditioning systems, especially in residential buildings, will not be required. In future, controlled ventilation systems will have to take on the additional function, as well as ensuring sufficient air renewal rates, of making sure that fresh air can not only be warmed during the winter by means of an earth heat exchanger, for instance, but also cooled down during periods of high temperatures in the summer. The efficiency and resilience of construction materials in extreme weather conditions will, presumably, play a greater role in future in the decision for or against certain designs and materials. For new development, forward-looking plans using new materials and designs are marketable. For the building stock, this is harder to implement. Existing construction is highly heterogeneous and overcoming climate-related problems is a more complex issue. Historic buildings, in particular, present a particular problem in this regard.
However, even in existing construction, most problems caused by climate can be overcome with refurbishment and modernisation measures. Factors such as "susceptibility to rain and damp" or "potential for storm damage" may, along with aspects such as "thermal insulation standard", "location" etc., become characteristics that determine the value of existing buildings and decide upon "sale or no sale" and even "preserve or tear down".
The dynamics of climate change reinforce the necessity to incorporate forecasts into standards, since buildings are not built for the short term but are planned, built and renovated for decades. The accumulation of extreme events accords foresight in construction, with the aim of preservation, a high significance. Regular checks and proper maintenance, in particular of outer shells, are proving to be essential in order to avoid disproportionate building damage and endangerment. This also applies to locations where climate changes are expected to influence ground conditions to an even greater extent.
Some existing buildings may turn out to be particularly sensitive to certain climatic consequences. For example, timber-framed buildings in conjunction with prolonged moisture penetration during the winter months, or the behaviour of wood as a building material under changing conditions. This must be observed and investigated more closely.
Forecast certainty and preparedness to take precautions go hand in hand. High uncertainty increases the risk of precautionary costs being spent where they are not necessary or do not lead to the desired results. Contradictory or clearly uncertain statements aggravate the situation with regard to instigating precautionary measures. An adequate forecast may currently be geared towards extreme events, that in all likelihood will occur more regularly in future (e.g. heat waves), or buildings are planned that can be adapted to further climate changes in a roughly 20 year cycle. It is particularly important to take into account small scale regional and local conditions with regard to such dynamic climatic changes. The flow of information for investors, building owners, planners, architects, engineers and specialist tradesmen must be directed towards these conditions. Municipal plans and activities (such as the identification of building land), knowledge gained from the results of current environmental monitoring and ecological risk analysis as well as planning and building activities by building owners must be coordinated.
The study closes with references to further research requirements.
The abstract is part of the German publication "Folgen des Klimawandels: Gebäude und Baupraxis in Deutschland", BBR-Online-Publikation 10/08, Hrsg.: BMVBS/BBR, Bonn April 2008
ISSN 1863-8732, urn:nbn:de:0093-ON1008R229
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