The Impact of Life Expectancy in LCA of Concrete and Massive Wood Structures - A Case Study of Strandparken in Sundbyberg
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Typ
Examensarbete för masterexamen
Master Thesis
Master Thesis
Program
Structural engineering and building technology (MPSEB), MSc
Publicerad
2014
Författare
Lundgren, Jonas
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Recently there has been an increase of energy and environmental certifications in the Swedish building sector which has led to the development of more energy-efficient building operation systems. Contradictory to this the greenhouse gas emissions for construction, maintenance, disposal and the other associative building sector stages have increased. The methodology of Life Cycle Assessment with its cradle-to-grave approach can be used to holistically evaluate the environmental load impacts of the entire building process. The building’s frame structure represents the largest part of material mass and is therefore crucial in the climate impact of the construction sector. Within the last ten years there have been several LCA comparisons between concrete and massive wood frames. These analyses more or less lack a life span perspective of each structural material. Life spans of buildings vary considerably due to climate conditions, lack of construction quality and maintenance continuity. In most cases the building life span is not depending on the structure, and additionally no consensus in variation of life span between the frame materials can be found. An LCA of two newly-raised multi-residential houses in the neighbourhood of Strandparken in Sundbyberg is performed comparing a CLT (Cross Laminated Timber) structure with a semi-prefabricated concrete system, using same construction requirements for fire, acoustics and insulation. The assessment results with limited system boundaries shows including variation of life expectancies that the carbon emission impact by wood and concrete is approximately the same. By extending the system boundaries to include reforestation the most outstanding reason for building with long-lasting wooden structures is the great potential of biogenic storage of carbon dioxide. In a complementary sensitivity analysis it is shown that through balanced harvesting and replanting methods it is possible to make the life cycle of wooden buildings close to climate neutral and act as a carbon sink for global warming. It is also concluded that the end usage phase is crucial for both materials where combusted wood could substitute fossil fuels or continue as carbon storage. Concrete on the other hand has a potential through carbonatation of rebinding up to half of its released fossil carbon dioxide at production, but wood as construction material is still a preferable choice for a future decreased climate impact by the building sector.
Beskrivning
Ämne/nyckelord
Building Futures , Byggnadsteknik , Building Futures , Building engineering