Building information modelling (BİM) based time (4D) and cost (5D)estimation for small scale buildings: A case study

In today's architecture, engineering, and construction (AEC) industry, the optimization of construction process and cost reflects an ideal to be achieved. Reliable quantity takeoff is the first step to achieve this goal. Building Information Modelling (BIM) is preferred over traditional methods and Computer-Aided Design (CAD) systems that create architectural drawing representations with the same principles thanks to its objectbased operation, ability to add attribute data, etc. However, despite its significant contribution to construction management, BIM software is still insufficient to adapt to climate conditions, location characteristics, and building type/size differences. In addition, although the construction process and cost estimations made during the design phase with attribute data have been strengthened, the professional intervention of a construction management estimator is inevitable. In this thesis, the reliability of the construction process and cost estimations for small-scale buildings in Turkey was tested using BIM technology. The design phase of the Fertek House, which was selected as an illustration, was carried out by the project author with CAD systems, and the quantity estimations were completed by the project contractor using traditional methods. For Fertek House, for which a 3D model was created via the Autodesk Revit (AR) tool, which is a BIM software, a virtual simulation of the application phase was performed by entering time (4D) and cost (5D) data via the Autodesk Navisworks (AN) tool, which is another BIM software. The results obtained following the real application phase were compared with the virtual application phase and traditional method estimates. When the estimations performed using BIM software were compared with the traditional method estimations, 15.34% less time and 2.5% less cost were obtained. When the Fertek House's actual application phase results were compared to the amount estimates, it was found that the BIM software's calculations provided 96% reliable results, whereas the estimates from the traditional approach provided 56% reliable results. When the concrete quantity estimates were compared with the results obtained from the application phase, it was determined that BIM software was 1.12% less and the traditional method was 6.79% more.