What is BIM? Part 1
Prologue
BIM of Building Information Modeling has become a buzzword today in the Building Industry.BIM is also one of the most misunderstood terms. Many people interpret BIM as software. Many look at it with scepticism or apprehension. Many of us, still do not understand, how BIM is used, where all BIM is applicable, and who should be using BIM. Is it worth my while to look into BIM?
In this series of posts, I will attempt to clear the mist over BIM. I will try to address the questions that many of us have in our minds. I’ll explore the definition of BIM, and how it is being used. What type and size of projects can utilize BIM? What are BIM’s advantages and limitations, and what is the future?
Definition of BIM
NBS defines BIM or Building Information Modeling as “… a digital representation of physical and functional characteristics of a facility. As such, it serves as a shared knowledge resource for information about a facility, forming a reliable basis for decisions during its life cycle from inception onward.”
In simple terms, the Intelligent 3D Model, such as Revit embeds Graphical as well as non-graphical information that becomes available throughout the building lifecycle. This information can help with informed decision-making.
The embedded information includes, though is not, limited to the following:
- Geometrical Information in terms of size and shape, colour and physical location
- Cost of Materials and assemblies
- Thermal Performance
- Time and assembly of elements that may take.
- Lifecycle or replacement time
As we see from the above, BIM includes a whole lot of information, that goes beyond the traditional dimensional information to include information that helps in analysis of Building performance as well as maintenance of a facility.
A core component of the BIM Process is a 3D Intelligent Building Model. The intelligent Building Model can store information needed for the BIM Process. Being an Intelligent 3D Model, it aids precise communication with the ability to bring together all the stakeholders on the same page.
The 3D Model together with a well-defined collaborative process form the BIM Process.
Uses of BIM
- The Collaborative BIM Process and the Virtual Building Model can be used for the following:
Document Exchange - Reviews and Quality Check
- Design Coordination
- Model Coordination
- Accurate Material Takeoffs and Bill-of-Quantities (BOQ) can be extracted from the Virtual Building Model
- Clash Detection between building elements such as Walls, Columns, Beams, Ducts and Pipes and so on.
- 5D Construction Planning (3D + Cost and Time)
- Daylight Studies and Green Building Analysis
- Design Documentation
- Planning Construction and Post Construction Facility Management
Benefits of BIM
Broadly speaking. BIM helps cut down costs of Construction, minimize clashes between building elements and ensure Projects get delivered on time. Building projects are a collaboration between the project promoter, the Design team and the Construction team. BIM defines this collaborative process and provides tools for effective collaboration.
The BIM Process
BIM generates graphical and non-graphical information termed as Data Sets. Typically, the BIM Process begins with (EIR) Employer’s Information Requirements. The EIR defines the Employer or Project owner’s expectations from BIM, the kind of information required from a vendor or supplier. This document formulates the Employer’s or Project owner’s objectives of BIM.
BIM Consultants develop BIM Execution Plan (BEP) based on EIR. BEP defines:
- The collaborative process,
- BIM Production Standards.
- LOD Levels required.
- Milestones and deliverables for each Milestone
- Review Process and Cycle
BEP also forms a legal document for a project.
Why do we need BIM?
Let us try to understand the need for BIM and why has it become so important.
Not so long ago, and even in many of the current situations, there is a disconnect between a Project Promoter, Architect, Engineering Consultants, and Contractors. Each one visualizes what is to be built differently. As a result, there is a shortfall in expectations, decisions could go wrong, costs rise, and there are construction delays.
This happens because of multiple reasons. Amongst these the following stand out:
Improper and ill-defined Communication between stakeholders at all stages of a project.
- Project Expectations and outcomes are not clearly defined.
- Lack of Pre-Construction Coordination
- Mixed up 2D CAD Drawings and 3D Revit Models
- Ill-Defined Document Production Standards
This lack of coordination and inadequate pre-planning often results in almost every stakeholder losing. BIM tries to resolve these very issues.
Understanding LOD
The level of Development is a specification that defines the level of information for each stage of a project. The basic specifications were developed by the AIA (American Institute of Architects). LOD specifications form one of the essential parts of the BIM Execution Plan (BEP).
The level of Development is the amount of information that goes into a BIM Model. Level of Development defines the level of design decisions that have been taken regarding a facility. This may be related to typical design stages of a Project:
- Pre-Design
- Schematic
- Design Development
- Permit
- BID/ Tender
- Construction Drawings/ GFC
- Construction
- As-Built
- Facility Management
The level of design Decisions or the amount of information about a project increases with each stage. The use or objectives of this information too changes with each of the stages. For example, at Pre-Design stage the information available is architectural Program requirements and Site information, Built up area and the total Coverage available.
As per BIM Forum LOD Specifications, the Model for this stage will be LOD 100.
The table below indicates the LOD for each stage:
LOD STAGE 100 PRE-DESIGN 200 CONCEPT 300 SCHEMATIC, DESIGN DEVELOPMENT, PERMIT 350 CONSTRUCTION DRAWINGS/ GFC 400 CONSTRUCTION/ SHOP DRAWINGS 500 AS-BUILT
BIM Dimensions
BIM Can be utilized for the entire lifecycle of a construction project. Each of these stages requires information specific to a stage. These can be as defined in the table below:
BIM DIMENSION DESCRIPTION 3D Typical Design with X,Y,Z Geometry 4D 3D + Time 5D 3D + Time + Cost 6D BIM for Facility 7D BIM for Sustainability 8D Health and Safety 9D Materials Management 10D Quality Management
This concludes part 1 of What is BIM
