BIM Case-based Object Base Cost Modeling at Schematic Design Phase

During the design stage, alternatives are continuously revised as proposals, reviews, and decisions are repeated. However, traditional cost models based on gross floor area fail to directly account for partial design changes and remain static until significant alterations, such as changes in total floor area or selection cases, occur. To address this, a cost model is needed to align budget management with evolving design decisions from the initial stages. This study utilizes BIM objects to translate cost information from similar cases into the target case within a BIM model, generating a spatial Bill of Quantities. Room-level chromosomes are extracted, and a genetic algorithm is applied to identify optimal solutions. The cost plan, linked to the BIM model, selects the design alternative with the minimum proximity value from the average ratio for each work type among the optimal solutions. The research introduces the Case-based Object-Based Cost Model, a tool for cost planning during the Schematic Design Phase. This model integrates specific design elements while staying within budget, offering a practical guide for comparing and evaluating design alternatives throughout the process.