The building industry currently accounts for about a fifth of Sweden's climate emissions. By 2030, the industries goal is to halve its emissions in order to have net-zero greenhouse gasemissions by 2045. From 1 January 2022, the Act on Climate Declaration applies to new construction. This is to try to draw attention to and reduce the climate impact of the construction sector in general.  This study has been done in collaboration with Umeå municipality. Umeå municipality has a preschool of six departments. The preschool is currently designed with CLT and stud wall, mineral wool insulation and slab-on-ground with water-cement ratio required at 0.38, and this building serves as a reference building. In this report, building materials are compared through climate calculation to investigate possible reduction of the preschool's climate impact. The climate calculation consists of an LCA in module A1-A5 with the same scope as the current legal requirements for the climate declaration. The comparasions that has been made are between climate impact of the CLT-frame againsta frame made of lightweight beams. Comparasion of three different insulation options, mineralwool, cellulose, and hemp as well as concrete with different water-cement ratio and strengths. In the concrete comparison, a short calculation on drying times was made to investigate the consequences of any replacement of the concrete strength. The calculations in this study show that the climate impact of the preschool, in stage A of an LCA, has a low value compared to IVL's recommended requirements when procuring a building of solid CLT-frame. The results for other comparisons showed that the most effective change is to replace the frame with lightweight beams instead of CLT and stud frame. This would result in a reduction in the climate impact of the load-bearing frame by 30%. Next comes the change of insulation to cellulose insulation, which would provide a reduction in climate impact by 25 % compared to mineralwool insulation. Overall, the building's climate emissions in stage A with the recommended solutions above could be reduced by 19-23,5 % depending on the choice of concrete in slab-on-ground and in terms of what drying time that is acceptable.