Constructing with wood : What are the economical and environmental benefits and barriers of using wood as a construction material

Detta är en Master-uppsats från KTH/Fastigheter och byggande

Författare: John Waldenström; [2017]

Nyckelord: Wood; environment; economics; trä; miljö; ekonomi;

Sammanfattning: One of the biggest issues of our time is the environment. In December 2015, 195 countries agreed to the first-ever universal, legally binding global climate deal, The Paris Protocol – A blueprint for tackling global climate change beyond 2020. The majority of politicians in most countries discuss transportation, industrial plants and factories as the big problem and focuses on this to reduce their impact on the climate. Unfortunately, they are forgetting one big factor, the housing, more specifically the construction of multi-family homes, which have a huge environmental impact. Concrete and steel, which are used in most constructions today, contribute to a huge extent to the emissions of the planet. The purpose of this study is to increase the knowledge of constructing with wood by focusing on the environmental and economical benefits and barriers. One way to reduce the impact that the construction of multi-family homes has on the environment, is to use other materials apart from concrete and steel, such as wood. There are several ways of constructing with wood and some examples are CLT, LVL and GLULAM. Where CLT stands for Cross laminated timber, LVL Laminated veneer lumber and Glulam stands for glue laminated timber. There is evidence that show that wood has a much lower environmental impact than both concrete and steel and this can be traced back to the manufacturing of the wood elements. LCA analyses that have been conducted differ depending on how long life-time they have been calculated for. For a LCA with 50-year life-cycle the wood performed 28 % better (Tove malmqvist, 2016), however when SP/Rise published one where they used 100 years there were no differences that could be determined (SP/Rise,2017). However, it should be noted that both reports state that a LCA comparison between wood and concrete houses are very difficult to make due to the different properties that the materials have, and therefore the reliability of the comparison is not that high.  One common notion is that wood catches fire more easily, although studies conducted show that wood can withstand fire in a sufficient manner according to law and regulations. Furthermore, the literature study concludes that even though a wood house could quite easily reach an environmental certification there are no evidence that point to the fact that one would get a premium for having such a certification in Sweden, however in USA the results are different and there are possibilities to get a premium. Since the construction time is shorter when constructing with wood, there might be some merit to the idea that we could reduce the housing shortage by constructing more with wood, although the literature study shows that there are other factors that have much higher impact on the housing shortage, such as the use of dwellings and the planning and building process. Regarding the cost of wood they are very similar to concrete and steel, which means that wood can compete when it comes to costs, although it should be said that the construction time is shorter with wood and thus mean that the cost are shifted to other parts of the project. This study shows that the most positive feature of constructing with wood is the environmental impact. However, there are more environmentally friendly types of concrete that could makes the differences compared to wood less, since concrete also absorbs CO2 during its lifetime. On the other hand, the most controversial aspect of constructing with wood is how well it copes with fire and water, more specifically the potential damages that can arise. Even though the fire resistance has been tested on numerous occasions and shown that it can meet current law and regulations, there have been no full-scale tests. This means that there are still some uncertainties, especially when it comes to property protection and how you replace or manage damaged buildings, an area where there is room for further research. This means that insurance companies shy away from wood buildings and if they would insure these buildings the premium would in almost every case be higher. Last but not least there are consensus amongst the interviewees that there is a gap when it comes to knowledge and education that need to be addressed in order for wood to become a real contender towards the traditional steel/ concrete structures.

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