Using BIM to Deliver Low-Carbon Wood Buildings
In the original design for the Sydney Opera House, Jørn Utzon envisioned the shells supported by precast concrete ribs under a reinforced concrete structure, which turned out to be prohibitively expensive. As one of the first projects to use computational calculations, the final solution – reached jointly between the architect and the structural engineer – consisted of a precast ribbed system of concrete shells created from sections of a sphere. At the Guggenheim Museum in Bilbao, the project team used CATIA software (typically used by the aerospace industry) to model and materialize the complex curvilinear shapes of the titanium-coated volume designed by Frank Gehry. Challenging projects tend to spark the creativity of those involved to make them possible, but there are constructive systems that interact well with existing technologies. This is the case, for example, with engineered wood and the BIM system. When used simultaneously, they usually achieve highly efficient and sustainable projects.
BIM (Building Information Modeling) allows the incorporation of a variety of valuable information into the model, in addition to the traditional three-dimensional views of walls, roofs or doors and windows, that permit design iterations and simulations. It also promotes collaboration and exchange of information throughout the team involved, from the first sketches to the end of a building’s useful life. In other words, from planning and design to operation and decommissioning, the information contained in the BIM model supports building management.
BIM has proved to significantly increase the productivity of designers, control costs (avoiding errors and rework), and reduce waste on-site. Other benefits include simplified communication between everyone involved in the project and better quality and management of information. According to a report by the Boston Consulting Group on digital tools in engineering and construction, broader adoption of BIM could save the global infrastructure market 15 to 25 percent by 2025. For wood buildings this requires the involvement of engineered wood manufacturers, consultants, designers and even the owners of the future building.
Mass timber buildings have a high potential to change the mindset of traditional construction, focused on craft practices at the construction site, which are often uncertain, risky and subject to lower productivity levels, resulting in unreliable costs and schedules. Wood is a material with low carbon content, easy to mill and to be pre-fabricated in controlled environments for on-site assembly, with precise dimensions, configurations and fittings that align precisely with the virtual model. Wood is also lightweight, yet sturdy enough to handle and transport.
By using the BIM system for engineered wood designs it is possible to obtain several improvements: in the design phase, the team can use BIM to develop and verify the primary wood structure and carbon performance of the design. The construction team can then use the digital model to build the design virtually, which helps them plan and execute the fabrication of the system components and rehearse the on-site assembly of the prefab parts. This can include the cutting plans, the perforations and the identification of each module for later assembly. Also, by adding other applications and software, those involved can generate energy simulations, create assembly sequencing, work logistics and even create realistic renderings integrating Virtual Reality – which can improve the comprehension of the project or even be used as a sales tool for future owners.
In BIM, there is the possibility of developing the project at various levels of detail (or Levels of Development – LOD): from a pre-design with little detail to an as-built documentation that lists everything that the building has after completion of construction. The system also allows the incorporation of the concept of so-called other design dimensions: in addition to 3D (the geometry of the virtual model itself), one can also include time (4D), cost (5D), performance (6D), and so on. Each dimension enhances the model with an extra data layer that provides information and details about “how”, “when”, “how much” and more.
Another possibility, suitable for engineered wood buildings, is the development of a VDC (Virtual Design and Construction). It is a method of creating a construction project virtually before starting it in the real world, which allows it to be “dissected” by those responsible for the work, before mobilizing materials, equipment and employees.
This is what the Brock Commons Tallwood House design team did, which included CadMakers Inc as a VDC modeler. The VDC model owner was involved in the process from the beginning, collecting the relevant information from the different team members in order to create a unique virtual model of the building with a high level of detail, identifying conflicts, refining and unifying the different areas when possible. In this case, they even developed a full-scale prototype, which provided a test of real-world design and planning assumptions and validated material choices. This comprises a section of the ground floor and a second floor, occupying 3 spans by 3 spans (about 12 × 12 m), including the primary elements and connections that are also in the final construction.
As with any innovation, there are barriers to adopting BIM, especially so that everyone involved is aligned and speaking the same language in the designs. But it is clear that construction industry professionals have recognized that embracing digitization and industrialization will bring countless future benefits. For prefabricated wood buildings, the advantages are notable, as they align the efficiency of prefabrication with the attractiveness of a natural and renewable material. And, above all, it is not necessary to reinvent the wheel or create new technologies for its practical application.
To learn more about BIM and wood buildings and the value that BIM can add in terms of improved efficiency, reliability and sustainability, read the Guide.
