BESLUTSTÖD FÖR BJÄLKLAGSVAL I PROJEKTERINGSSKEDET : EN JÄMFÖRELSE AV KLIMATPÅVERKAN FÖR OLIKA BJÄLKLAGSTYPER

Sammanfattning

Introduction – In 2022, the building and property sector accounted for slightly more than a fifth of the total greenhouse gas emissions in Sweden. Within the sector, it is shown that the production of building materials is responsible for 80-85 % of the climate impact during the construction stage for a new production. Due to this, it is of great importance that materials in the design stage are chosen with consideration for their climate impact. The choice of material becomes essential för building components such as floor slabs as they make up a large proportion of the total built area. The aim of the study is to provide a basis to ease the choice of floor slabs in the design stage, with a focus on climate impact and cross section height. Method – The conditions for the study is that six different types of floor slabs are examined, all of which have the same requirements in terms of load-bearing capacity, sound and fire. The floor slab types that are examined include a ribbed slab, a flat slab, a hybrid slab with glulam beams, a hybrid slab with CLT panel, a hollow-core slab and a hollow-core slab with climate improved concrete. The floor slabs are examined for use in schools, offices and hospitals as well as for the spans 6-12 meters. The study is a quantitative study where two data collection methods are used, which are calculations and document analysis, to answer the research questions. Results – The result for the study consists of climate impact and cross-sectional heights for the floor slabs. The empirical data is gathered in tables and charts to clearly show the differences in climate impact and cross-sectional height for the different floor slabs. Analysis – The analysis of the empirical data shows that climate impact varies depending on the composition of the load-bearing structure. Floor slabs with a load-bearing structure consisting solely of timber products have a lower climate impact compared to hybrid and concrete floor slabs. By comparing the climate impacts, it is shown that the hybrid floor slab with CLT panel and the hollow core floor slab had the highest emissions. The analysis shows that for cross section heights the ribbed floor slab, the hybrid floor slab with glulam beams and the hollow core floor slab had the lowest height for spans 6-7 meters. For the spans of 10-12 meters, the hollow-core floor slab still had the lowest cross-sectional height. Discussion – A comparison could not be made between all floor slabs for all spans. The reason being that the floor slabs sometimes did not meet the design requirements or that some manufacturers couldn’t supply enough technical information for the floor slabs regarding dimensions and climate data. Regarding the differences between concrete and timber floor slabs, the results are consistent with previous studies. However, the results for the hybrid floor slabs differ from previous studies. The results showed that one of the hybrid floor slabs was the floor slab with the highest climate impact, whereas previous studies have indicated that hybrid floor slabs have a lower climate impact than concrete floor slabs. A reason for the difference in results could be that in previous studies biogenic carbon is included in the calculations, whereas in this study they are excluded.