Introduction: Sweden's climate creates several challenges to achieve habitable indoor climate. In Sweden, it is most common for detached houses of wooden construction to use mineral wool or wood fibre to insulate the exterior walls. While mineral wool and wood fibre are the most popular choices, there are several other alternative insulation materials that can be beneficial. The thesis deals with four insulation materials where stone wool and wood fibre are pitted against the more modern materials PIR and PUR to investigate which is most advantageous with the help of life cycle analysis, life cycle cost analysis and energy use in production, installation and end of life. The three criteria are then summed up in a multi-criteria analysis to decide which material is most beneficial. 

Method: To reach a result, a literature study and case study is conducted with life cycle analysis, life cycle cost analysis and energy use. The life cycle assessment answers question 1, the life cycle cost analysis answers question 2 and the multi-criteria analysis answers question 3. 

Results & Analysis: Four different insulation materials in a wood-constructed wall were studied where PIR and PUR were considered in two different forms, onewith the same U-value as the stone wool and wood fibre, the other with the same thickness as the stone wool and wood fibre. The different variants are studied using the different criteria in the multi-criteria analysis. The material that has the best environmental impact in the life cycle analysis is wood fibre and then the thin PIR, stone wool, thick PIR, thin PUR and lastly thick PUR. In the life cycle cost analysis, the stone wool is most price efficient, then wood fibre, thin PIR, thick PIR, thin PUR and the most expensive price has the thick PUR. The material with the least energy use throughout the life of the material is wood fibre which is 100 % recyclable, after the wood fibre comes stone wool, thin PIR, thick PIR, thin PUR and the most energy use for the life of the material has thick PUR. Finally, the different results are summarized and show that wood fibre is the material that is most advantageous with the criteria chosen, while the thick variation of PUR is the least advantageous in both environmental aspect and cost. 

Discussion: The three methods of analysis that have been used in this work have their advantages and disadvantages. The advantages are that they show concrete answers, and the disadvantages are mainly the programs they are performed on. Input into these programs has been thorough, but as they are slow and difficult to navigate, there may be a risk of errors. The multi-criteria analysis should be reviewed, and more criteria examined is recommended.