Estimating construction costs using BIM

     Cost estimation with BIM also known as BIM 5D can be done by connecting a 3D model to an estimation database (a 5D cost library).  Higher level of details can be applied to these estimates at various stages of the project. 3D models are fed with multi dimensional objects and related information about the elements of these objects - for example, the quantity and specification details. Here, in BIM, the information about each element is associated with the corresponding geometry. Any change in the design, leads to change in geometry and hence the associated information also instantly changes (updates). This in-turn enables accurate and efficient cost estimation, by eliminating the need for manual take offs that are highly error prone. 

BIM Cost estimation

     Building information modeling is only as good as the information that is fed into it. While using BIM for cost estimation, it is solely an estimator’s responsibility to develop information database that is useful for estimation. Cost estimation, i.e. the 5Th dimension of BIM, constitutes of multiple layers of activities, including cost planning, quantity extraction, and verification of - MEP, structural and rebar fabrication models and visualization of series of activities with corresponding accrued costs and verifying the same. Hence the importance of an experienced and knowledgeable cost estimator cannot be valued less.
 

Why accurate cost estimation drives the efficiency of a construction project?

     Cost estimation means, predicting the most realistic figure at different – or any given stage in a project.  This prediction is done based on the interdependency of time, cost and activities. Highly accurate estimations; lessen the changes of uncertainties and risks. The accuracy of cost estimations is also very pivotal for bids and tenders, as after the assessment of risks and uncertainties, overheads are added to the estimates and turned into tenders.

Source: https://www.bimcommunity.com