LCC och LCA för stommaterialen KL-trä och betong : En jämförande fallstudie av Täby hus 7-8

The purpose of this study is to investigate two different building materials for the construction of the framework of two apartment buildings by the name of Täby house 7-8. The materials used for the framework are typically cross-laminated timber and concrete. Wood is a naturally occurring and renewable building material that mainly consists of lignin, cellulose, and hemicellulose. Cross-laminated timber is a building product that consists of an odd number of layers (3, 5, 7) that are glued together at a 90 degree angle to the embedded layer. Concrete can be recycled but is not a renewable building material. Concrete is a mix of stone, cement, and water. The lifespans of the materials are very good and with maintenance, they can be very long. In construction, managers estimate lifespan of the building materials to be between 70-100 years, this study assumes a lifespan of 100 years. The focus of the study is on the cost efficiency and effect on the environment. To investigate the cost efficiency, an Life-cycle costing (LCC) study has been performed while the effect on the environment is assessed with an Life-cycle assessment (LCA) study. The LCC study includes production costs of the construction for the two different houses. The management costs are also measured, however, due to the frame not being a part of the facade, it doesn't affect the management cost LCA studies are performed, on each material. The studies are cradle-to-grave. The management is not included in the LCA-studies as the framework does not affect the environment. The results of the LCC yielded 18 718 [SEK/m2] for the concrete frame and 17 281 [SEK/m2] for cross-laminated timber (CLT). Results showed that CLT is 1 437 [SEK/m2] cheaper than concrete. The results for the LCA yielded 200 [kg CO2/m2] for the concrete frame and 128 [kgCO2/m2] for CLT. Results showed that the concrete frame has 72 [kg CO2/m2] more emissions than CLT. The literature overview and the interview studies found that a building with a frame consisting of CLT is more cost efficient and has a lower environmental impact than a building with a concrete frame. This is with the assumption that the other components used in the building are similar between the two studied buildings.