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- Cristescu, Carmen, et al.
(författare)
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Design for deconstruction and reuse of timber structures – state of the art review
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is a state-of-the-art on timber construction in selected european countries and and discusses technical premises for a potential circular use of timber in building construction, focusing on Design for Deconstruction and Reuse (DfDR) in low-rise timber buildings, up to 3 storeys. It describes the historic and contemporary building techniques of timber buildings in all project countries (Sweden, Finland, Ireland, UK, Spain, Germany, Slovenia) and finds, that all of these countries have a long history of building with timber, but in most regions other materials dominated the housing output from the beginning of the 20th century. Only in the second half of the 20th century timber started gaining importance as a building material in Europe again, with light timber frame construction becoming an important construction system. From the beginning of the 21st century, innovations in the sector started transforming the construction industry. Mass timber products like CLT opened the market for high-rise timber buildings and in some countries office blocks, schools and hotels are built using timber, although the majority of timber construction remains residential. An even more important development might be the uptake of offsite construction, that makes timber construction more accurate, material efficient, fast and it reduces waste. These modern methods of construction are gaining importance in the construction sector of all partner countries and are likely to dominate the European housing output in the future. There will be some regional differences in the level of prefabrication, material choices and designs, so that any design guidelines for DfDR need to be adapted to the regional context. However, modern timber construction is not currently aligned with circular economy principles and is seldomly taking buildings endof-life-into account.Therefore, the report continues to summarise novel design concepts for deconstruction and reuse, that could be used in modern timber buildings. It outlines that the feasibility as well as the reuse potential depends on the scale of reclaimed components, where larger components and assemblies are often considered beneficial in terms of time, greenhouse gas emissions and waste production. If volumetric or planar units could be salvaged in the future, they also need to be adaptable for altered regulations or standards or alternative functions. It is further necessary that assemblies can be altered within buildings, since different building components have different life expectancies. Various examples for DfDR in buildings with the accompanying design strategies are presented. The buildings in the examples are often designed to be in one place for a limited timeframe and can be deconstructed and re-erected elsewhere without replacement of components. Key-features often include modularity of components, reversible connections, adaptability of the floor-plan and circular procurement. Even though it is evidently possible, the structural reuse of timber is not a wide-spread approach to date. Barriers to the use of reclaimed structural components are mainly a lack in demand for salvaged materials, but also prohibitive building regulations and the lack of design standards. Demolition practices play a crucial role as well and need to be considered in the design of buildings, to avoid damage to the components.Finally, the report summarises principles and guidelines for DfDR by different authors. As a generic approach an indicator system for deconstructability and reusability could be introduced. Time, Separability, Risk and Safety, Simplicity and Interchangeability are identified5as the main indicators for DfDR, that remain somewhat abstract. As opposed to using a generic indicator system, a more practical approach of assessing DfDR on an individual basis could be taken. This way specific shortcomings of the design can be addressed. But if DfDR found a wider application in the future, this approach may be too time consuming and there is a need for a more directed decision-making tool that can be used during the design phase of buildings to enhance DfDR. As the InFutUReWood project proceeds, it will examine a more granular approach to DfDR, relating it to the actual construction stages used in practice, developing a general template to be appropriated and adjusted to account for regional variations in construction. A strategic matrix is in development which will provide designers with a methodology based on relating principles, strategies and specific tactics to the typical design stages, to aid design decisions that promote DfDR.
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