Toward a standard format for describing objects in digital models

The deployment of building information modeling (BIM) depends on its full adoption by all construction and urban development trades. This new working method enables the various stakeholders in a project to share all information about the "objects” in a digital model of the building and city, beyond just visual representation. Prerequisite: share the same BIM language to describe and interpret the properties of each object. The CSTB is developing a complete "wall object” using BIM. This task contributes to experimentation with the PPBIM (Construction Product Properties for BIM) standard.

In digital models, BIM objects are virtual avatars of the industrial products that make up a building and its environment. Various characteristics (geometry, dimensions, thermal performance, acoustics, etc.) are linked to them and shared with all project stakeholders, from design to construction to operation.

The CSTB was approached by the firm Conseil Protea to define a generic "wall” object and its characteristics in BIM format. The goal is to identify all the properties necessary for stakeholders to use it productively in the project.

Every trade has its needs

Every stakeholder must collect the specific information they need from the digital model. For instance, the "structure” consulting firm looks at properties concerning the mechanical strength of walls, while the architect considers appearance and the construction economist looks at dimensions and composition, as well as the space it occupies. The list of properties that each trade needs is long.

As part of its study, the CSTB identified several dozens of properties required for describing a wall object. Some examples: appearance of skins, acoustic insulation, thermal resistance, compressive strength and fire rating.

Definition and application of the PPBIM standard

The CSTB is deploying its expertise, in collaboration with Protea Conseil, as part of a broader experimentation, supported by the Digital Transition Plan for Construction (PTNB) for the development of a French strategy for standardization in conjunction with BIM. The goal is to develop open formats that optimize information sharing and the interoperability of BIM software.

It involves validating the XP P07-150 standard, better known as PPBIM. The purpose is to standardize the classification and creation of BIM object characteristics for construction products.

In the very short term, the study should produce libraries of generic objects. They will help designers to define the expected properties of products before consulting with companies (tender document preparation phase prior to execution) and choosing a specific product from an industrial company. The challenge is to allow for variants and preserve competition.

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