Using BIM as a Tool to for LEED Score Calculations
Although LEED is a rating system and BIM is an information technology, the advantage of using BIM is that it can be a resource of all project information for team members from the design team, consultants, and facility. It would assist project stakeholders in making decisions for new and existing buildings considering the best value with regard to the applicable green building rating system score. Using BIM in this approach could allow designers to study alternatives more quickly in going after LEED points, to make timely decisions, to communicate effectively both during design and construction, and when submitting documentation for the LEED worksheets. With better advances in the material libraries and cost estimation, the design team could use the techniques to go beyond the LEED certification system.

The LEED NC Material Resources Credit 4 was described previously; this credit is about construction materials’ recycled content that requires project use materials with recycled content at least 10% or 20%, based on cost, of the total value of the materials in the project. In LEED, the AEC teams need to document the following information to achieve this credit: Material Name, Manufacturer, Material Cost, Post Consumer Recycled Content, Pre-Consumer Recycled Content, and Recycled Content Information Source. It is possible to add fields for this data as shared parameters inside BIM and give values to these parameters according to manufacturers’ specifications. Then a schedule can be created. Because not all the materials qualify for this credit, different phases should be created and defined for each component and material. After that, a material takeoff schedule can be created by selecting different material categories and phases, and the the material group can be selected that is qualified for the credit. The specific parameters, as required by LEED template, are added to the schedule along with a few simple formulas to calculate the recycled content value.
Recycled Content Value = Percent Postconsumer Recycled Content × Material Cost + 0.5 × Percent Preconsumer Recycled Content × Material Cost
Percentage Recycled Content = Total Recycled Content Value / Total Materials Cost
Besides that, a cut sheet can be created in Revit for each credit. In this cut sheet, designers can add basic description for this credit and the schedules in it. And then save the file contained with these schedules and cut sheets as a template. For every new project, they can use this template to start their design, and use the materials and components from the library they created. With the progress of the model, the schedules will also automatically update. By viewing the cut sheets, designers can easily know the credits and their progresses.

