## 1 Introduction  
### Background and Objectives  
Building information modeling (BIM) has contributed significantly to improving the performance of buildings and infrastructure, and BIM-based design methods have been actively researched with the objective of enhancing productivity in the architecture, engineering, and construction (AEC) industry [1]. BIM enables AEC professionals to perform automatic extraction and utilization of the information required in implementing a range of AEC projects; this was conducted manually in the past. Thus, it has significantly reduced the time and human resources required to conduct such projects, thereby improving the efficiency and accuracy of the process. Nevertheless, the implementation of BIM still has disadvantages and limitations [2]. One difficulty in architectural design using BIM is that the information that can be utilized for construction cost estimation varies depending on the level of detail (LOD), and models of LOD 350 and LOD 400 or higher are required in many cases. However, the use of a BIM model of LOD 350 or higher implies that the construction project has been developed with precise quantity of building elements and that other specific information and detailed plans have been implemented. These details are difficult to handle in construction cost estimation in the early phase of the project. Economic feasibility and cost analysis performed during the architectural planning stage in the early phase of construction plays a key role in project management and significantly affects the future progress of the project. In addition, the results of conceptual cost estimation that serve as the criteria for making judgments on economic feasibility and validity in the early phase of a construction project form the basis for decision making, and the reliability of the information provided at this point is directly related to the success or failure of project execution [3]. In the architectural planning stage, because the project information that can be utilized for decision-making is limited, the amounts of information and human labor required for cost estimation may be small, but the estimates in this stage significantly influence the project expenditures across the project lifecycle [4]. This is attributed to the fact that 80% of the total cost of a construction project is determined or implemented during the design stage, and only 20% of the cost can be adjusted during the stages after design completion [5]. With further progress on the project, the possibility of reducing the final cost decreases, and the estimate made in the early phase of the project can serve as the main reference point for discussion and decision-making. Therefore, high accuracy estimates that account for the actual environment and situation are required. Currently, the most widely applied method of construction cost estimation in South Korea is based on construction cost information per unit area. Although this approach is useful in the early phase of a construction project, when the available information is limited and the construction cost needs to be estimated as rapidly as possible, the accuracy of the cost estimation at this stage is low in the actual execution of projects [6]. This low accuracy occurs because these approaches do not account for factors other than the area-related information in the process of estimating the construction cost per unit area. Estimation errors occur due to changes in the information with the progress of the design process, and the resulting estimates often fail to show correlations with the estimates in the architectural detail design phase of the construction project [7]. These characteristics indicate that in the early phase of a construction project, when the design information has not been confirmed and the information available for construction cost estimation is limited, the construction cost estimation considering a unit area alone cannot provide a reliable basis for making accurate judgments.