Kvalitetssäkring av objektsbaserade IFC-filer för mängdavtagningar och kostnadskalkyler : En fallstudie av levererade konstruktionsmodeller, vid Tyréns AB Stockholm

To perform quantity takeoffs and cost estimates based on 3D models is problematic, if the models do not meet the expected demands of information. The weaknesses of the models leads to uncertainty when the calculator will establish cost estimates, which forms the background to the issues that the thesis constitutes.The project Biomedicum is conducted as a full-fledged BIM project, where the object based 3D models are the basis for cost estimates in the system phase. The calculator in the project has expressed dissatisfaction regarding the quality of the models, and believes that there are major flaws that lead to the risk of uncertain calculations increasing.Of this reason, this thesis will analyze the possibilities about ensuring the quality of an object based 3D model in IFC format, by using the software Solibri Model Checker.This thesis consists of a literature review, interviews and a case study. The case study examines whether Solibri Model Checker is capable of checking the models based on the project specific requirements, and to analyze the results of the checks that have carried out in the case study.The interviews have been the basis for the number of problems that have been considered relevant for the thesis. Problems that can be traced to legal difficulties, lack of a common set requirements, disagreements about the content of an object based 3D model etc.The case study has shown that the 3D models are inadequate to perform cost estimates, which leads to difficulties and uncertainties in the calculation process. There are several reasons for this. The designers of the project have used wrong modeling technique for quantity takeoff and cost estimating. But also that there are no clear guidelines as to what information should be included in the items in the document stage system, which has emerged during the interviews. It has also emerged during the interviews that crucial problems that may be linked to the models are of poor quality, because it has not been required early enough in the process.What is important to get a working process in which the object-based 3D models to be used for quantity takeoffs and cost estimates, is that in the early stages determine what information is needed in the objects to credible estimates will be possible to establish. The importance of a clear IT manual is also great, as it is the manual who serves as the basis of the information to be included in the models.