Material Choices for a Fossil-Free Preschool - An Interview Study on How Materials are Chosen, and a Life Cycle Assessment of Hemp Insulation

Abstract

Many of the materials used for constructing a preschool today are not fossil-free. Therefore, the administration of premises of the City of Gothenburg (Lokalförvaltningen) has decided to construct a fossil-free preschool as a first step towards the goal of becoming fossil-free before the year 2030. Thus, the purpose of this thesis was to contribute to the development towards a fossil-free construction industry by identifying the process of material choices for a fossil-free preschool and to assess if the choice of insulation material in an exterior wall could be fossil-free. The assessment of insulation materials was performed by comparing the standard material mineral wool with hemp insulation as an alternative material. A mixed methods research was conducted in this study. This included a qualitative interview study on actors in the industry and a quantitative life cycle assessment (LCA) of hemp insulation where GWP100 was assessed. Further, the global warming potential (GWP) of hemp insulation and mineral wool was compared. From the interview study, a result was that some of the interviewees thought that the client makes the material choice and others thought everyone makes the choice. However, the results are coloured by the methodological choice to only interview ten actors. Regarding the definition of fossil-free materials, some thought it aimed to the raw material while some thought it aimed to the whole lifecycle of a material. Further, the interviewees also had multiple suggestions regarding how the material choices can be affected, e.g. by green public procurement. The LCA was conducted on a cradle-to-gate basis. A result from the LCA was that the GWP of hemp insulation is -1.15 kg CO2e per m2 hemp insulation if biogenic CO2 of - 1 kg CO2e per kg hemp plant is accounted for and if it would be produced in Sweden. Compared to mineral wool, hemp insulation would be superior since mineral wool has a GWP of 0.62 to 1.94 kg CO2e per m2 insulation. From the results of the literature review, the interview study and the comparison, several conclusions were drawn. One conclusion was that it is important to state a clear definition and set boundaries of fossil-free to enable fossil-free materials to be chosen. Further, the actors in the construction industry have different opinions regarding actors’ possibility to affect the material choices for a fossil-free preschool. Another conclusion drawn was that the methodological choices of an LCA, highly affect the results. The comparison between mineral wool and hemp insulation resulted in the conclusion that hemp insulation could be a better option for a fossil-free preschool than mineral wool