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BIM for predemolition waste audit in practice

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An accurate and swift identification of materials, quantities and building typologies before the demolition works is needed for an efficient waste management and recovery of raw materials from buildings. A BIM based tool developed in HISER is being validated for this purpose in several real buildings.

 

Quantification of construction and demolition (C&D) waste is essential for effective waste management. The estimation results could provide fundamental data for practitioners to evaluate the true size of the waste and hence, make the adequate decision for their minimization and sustainable management. However, tools for accurate estimation of C&D waste are lacking. Existing tools and methods are not convenient enough for contractors to be willing to utilize without spending too much time and effort since information such as material volume needs to be either measured or retrieved from not always updated documents manually.

 

The HISER project has developed a Building Information Modelling (BIM) based tool to support the collection and management of information of materials through smart processing of data in the pre-demolition stage. The expected benefits include improved reliability of calculation, easier traceability of materials and quicker evaluation of alternative demolition/recovery options. The tool is being integrated with a commercial software to facilitate the management of an existing basic architectural BIM file (ifc) or the creation of a simple sketch of the building. In addition it can also import the HISER tool results for planning and managing the demolition works.

 

The tool uses the geometries and defined top categories (walls, slabs, columns, beams, windows, doors, stairs…) to produce an inventory of the building. The user selects the elements present in the building from a tree list or a 3D visualisation window from the portable editor. Details of the elements are defined using databases linked to the tool and parameters. Most of those parameters are automatically completed by the tool from ifc geometrical information (area, length, width…) or mean values (material densities, reinforcement ratios…) but all of them can be modified by the user. Properties from one element can be spread to other elements (in general or on a specific floor), which facilitates the inventorying process in the case of many repeated elements (columns, windows…). When all the elements to be demolished are inventoried, the tool automatically calculates the amount of waste materials, presenting a summarized report with elements, materials names, codes from the European List of Waste, weight and volume.  

 

This tool is being demonstrated in several demolition projects through case studies including a range of geographical situations and typologies in 2017. For each project, the demolition planning will be carried out by means of:

a) traditional practices (e.g. inventory based on visual inspection, templates and electronic sheet provided by the public bodies, etc.)

b) definition of BIM geometric model, identification and quantification of waste materials, data processing by means of the BIM-SD and automatic generation of waste management documents.

Accuracy of materials amounts time and cost for each alternative will be compared at the end.