The choice of buidling materials and the decisions that are made early on in the construction phasehave a great effect on the outcome of the project. Just like building materials, modeling is animportant part of every project and this degree project combines modeling with choosing buildingmaterials in order to compare two concrete buildings in a program called RFEM.The buildings are modeled with the same dimensions. It is 10 floors with a floor height of 2,4 meterswhich gives a total height of 24 meters. The buildings are 30 meters in length, 10 meters in width andare designed for a dwelling house in Stockholm.Cast-in-place concrete has been used for the first model and prefabricated for the second model.Results for selected members have been analyzed and discussed by applying loads, calculating loadcombinations and creating result reports in the program.A manual has been made in addition to modeling in RFEM. The manual serves as an addition to thisdegree project and describes how to create the models for the cast-in-place and prefabricatedconcrete building in RFEM step by step.Although both models have been built similarly, but with certain modifications according to therequirements, there have been noticeable differences in the results between the cast-in-place andthe prefabricated model. The differences in the results have been analyzed and various connectionshave been established even though it has been a challenge to compare two models that are notentirely identical regarding the construction.The contribution of loads, deformations, internal forces, transverse forces and moments have beenstudied and the results show that the deformations that occur on the shorter side of the building inmodel 2 depend on the columns that have been excluded because of the beams that the hollow coreelements are placed on. The difference in the loading of the columns has also been identified anddiscussed in this project.