What is Building Information Modelling?

What is Building Information Modelling?

Building information modelling (BIM) is a collaborative process for creating and managing information about a built asset across its entire lifecycle, from initial design through construction and into long-term operation. At its core, BIM is a data-driven approach where the "I" stands for Information, making it a fundamental shift in how project teams share data and make decisions, rather than just another software tool.

What is building information modelling?

Building information modelling is a structured method of generating, storing, and exchanging digital information about a physical structure. Unlike traditional 2D drawings or even basic 3D models, BIM centralizes every piece of asset data into a single, unified source of truth. This includes not just geometry but also attributes like material specifications, manufacturer details, performance data, and maintenance requirements. The purpose of BIM is to ensure appropriate information is created in a suitable format at the right time so that better decisions can be made throughout the design, construction, and operation of built assets. This makes BIM a process, not a product, a way of working that connects people, workflows, and data.

BIM is more than just a 3D model

A common misconception is that BIM is simply an advanced version of 3D CAD. While a BIM model does contain three-dimensional geometry, it is fundamentally different because every element within that geometry carries intelligent data. For example, a wall in a CAD drawing is just lines; in a BIM model, that same wall knows its height, thickness, thermal properties, fire rating, cost per unit, and even its expected service life. This rich, data-rich environment means the model is not just a visual representation but an intelligent database. It contains information about structural elements, materials, quantities, spaces, systems, costs, schedules, and maintenance plans. This unified source of truth eliminates the guesswork and version-control issues that plague traditional drafting, ensuring everyone works from the same accurate, up-to-date information.

The dimensions of BIM: 3D to 7D

While the 3D model provides the spatial foundation, BIM extends far beyond width, height, and depth. These additional "dimensions" add layers of data that enhance project delivery and asset management. The most common breakdown includes:

• 4D (Time/Scheduling): Adds a time element to the model, linking construction activities to the 3D elements. This allows teams to simulate the construction sequence, identify potential delays, and optimize the build program before breaking ground.
• 5D (Cost): Integrates cost data directly into the model. Quantities are extracted automatically, and any change to the design instantly updates cost estimates, enabling real-time budget control and reducing the risk of financial overruns.
• 6D (Facilities Management): Focuses on the operational phase of the asset. It embeds data about equipment warranties, maintenance schedules, and operational manuals directly into the model, making it a digital twin for ongoing facilities management and as-built operation.
• 7D (Sustainability): Adds environmental and lifecycle assessment data, including energy consumption, carbon footprint, and material recyclability. This dimension supports long-term sustainability goals and helps in achieving green building certifications.

They transform BIM from a design tool into a comprehensive business tool.

How the BIM process works

The BIM process is a structured workflow that relies on collaboration among all disciplines. It generally involves architects, engineers, and other specialists creating information-rich models of their respective scopes. Here is how it typically unfolds:

1. Creation: Each discipline (architectural, structural, MEP) develops its own model using BIM-authoring software. These models are not just geometry; they contain the specific data relevant to that discipline.
2. Combination: These individual models are then combined into a shared, federated model within a Common Data Environment (CDE). This provides a single, coordinated view of the entire project for all stakeholders.
3. Coordination and clash detection: The combined model is reviewed to identify conflicts, for example, a duct colliding with a structural beam.
4. Extraction and use: Once the model is coordinated and approved, it is used to extract quantities, generate documentation, create construction schedules (4D), and develop cost plans (5D). This approved information becomes the basis for fabrication, installation, and construction planning.

This iterative loop, design, combine, coordinate, extract, continues throughout the project, ensuring that the information remains accurate and actionable from concept to handover.

BIM is a cradle-to-grave process

Perhaps the most powerful aspect of building information modelling is that it is a cradle-to-grave process. The information created during design and construction does not become obsolete once the building is finished. Instead, it is handed over to the owner or facility manager as a digital record of the asset. This digital twin contains every detail needed for long-term operation, maintenance, and eventual disassembly. For example, a facilities team can query the model to find the exact location of a valve, check its maintenance history, and order a replacement part, all without leaving their desk. During renovations, the model provides a precise as-built record, eliminating the need for costly and uncertain site surveys. And at the end of the asset's life, the model can be used to plan safe and sustainable deconstruction, identifying materials that can be recycled or reused. This end-to-end information flow ensures that the value of the data is realized for the entire lifespan of the built asset, not just during its creation. The result is reduced operational costs, improved asset performance, and a more sustainable built environment.