A BIM project requires models to carry new and relevant information at every stage of the project. Ensuring that the information incorporated into the models is up to the only level required by the project BIM Goals
will help keep the models light and easy to manage.
Models are broadly classified into various dimensions based on the type of information incorporated into them.
The ‘Information’ incorporated in BIM Models is what sets them apart form the empty 3Dimensional models developed only for design visualization. BIM Models have the capability to carry all kinds of information that is required in a building through out the building life-cycle. However, this can get overwhelming and complicated without having an organized procedure to manage the information at respective stages.
- Dimensions in BIM
BIM Dimensions such as 3D, 4D, 5D etc classify the models based on the intended use for the models. Each BIM use requires a specific set of data set (project information) incorporated into its model elements. Categorizing project models based on its data will help to have a standardized model development and management process during the execution. - Level of Detail (LOD)
Level of Detail/Development is the term used to further categorize the models in various levels of completion. One of the prominently used standards for LOD is defined as 100,200 etc based on the amount of information incorporated in to the model either in 3D or in 2D. It is important to be aware that many LOD standards available in the industry should only be used as guidelines. Each project should have its own LOD Matrix based on the project uses and BIM goals.
One of the main challenges faced during execution is to manage and maintain the integrity of the information incorporated into the models. It is very easy for designers or model authors to get carried away and add 3Dimensional information not relevant for the BIM use. This can be avoided by having standards and templates in place. Quality check procedures should established to ensure that the models are following the right standards.
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3D – BIM
3D – BIM models are developed during the deign phase of the project to help visualize and communicate the design intent representing the building geometry using accurate sizes. These BIM Models are different from the traditional surface extrusion models. 3D-BIM Models are organized by real world building element categories such as walls, doors, windows etc.
Although 3D is a generic term used, BIM models vary greatly from the traditional surface based models. They are required to carry certain amount of information to be considered as BIM Models.
3D-BIM Models are object based models developed with components representing the real world building elements like walls, doors, windows etc.
The models should contain accurate sizes (length, width & height) for certain design defining components . Some of the information can be incorporated into the model using parameters or by representing on 2D drawings based on the project BIM use.
Depending on the purpose of the models, an LOD Matrix should be developed to help guide the modeling team to decide 3D v/s. 2D information required in the models.
- Visualization
3-D BIM Models in majority are used for visualization purposes. However, to successfully generate quality output from the models are required to contain accurate geometry and high-quality material assignment wherever needed. - Coordination
BIM Models used for coordination are more complex and require information beyond accurate sizes. The BIM coordinator must be able to categorize the model elements into various disciplines and groups easily. This will help with prioritizing and color coordinating the models during design coordination. - Quantity Take-off
BIM Models developed for quantity take-off exercises require the files to be organized and elements broken down in a certain way. The modeling methodology and naming conventions are the two important things to consider during this activity.
4D – BIM (Time)
Models carrying information regarding the construction schedule incorporated into each building element in 3D are considered to be 4D-BIM Models. 4D–BIM Models are developed during the construction planning stage. These are used to simulate, analyze and develop the construction schedule.
“Time” is considered as the 4th Dimension in BIM. Models are generally transformed from 3D to 4D either by adding the schedule related information to each element or by synchronizing the traditional project plan (data sheet) to the 3D model.
4D BIM Models are generally used to develop a sequencing animation of all the activities on-site along with the building construction, site-equipment, procurement etc. Sequencing animation helps the project team to identify issues and plan the entire construction process avoiding any potential risks up-front.
- Project Phasing
By simply grouping respective model elements into the phase they belong to by using time parameter, the project team can visualize the planning concept including construction zoning, temporary vs permanent structures etc. - Construction Simulation
Being able to visualize the project growing virtually before ground breaking gives great power to the stake holders. A general guide line while developing models for construction simulation is to consider develop the model exactly as it would be built on-site. This helps the team to easily incorporate particular date & time to each model element while developing the simulation. - Buildability Study
BIM models with sequencing animations enables the team to evaluate the buildability of a project. Buildability score, currently being practiced in the industry is a numeric value assigned to the design based on the buildable nature of the project. - Schedule Monitoring
By having the 4D BIM Models to monitor the construction activities on-site increases the understanding of the project status among all stake holders. 4D BIM Models help the team to assess the risks and plan the logistics accordingly.
5D – BIM (Time + Cost)
Models when used for detailed cost-estimation of the project by incorporating the information specific to material volumes, cost per unit etc are considered to be 5D Models. 5D Models are used during the project planning through the construction process to manage the budget with visual and information rich value engineering process.
“Cost” is considered to be the 5th Dimension in BIM. 5D BIM Models are used to estimate the project budget. This is achieved by integrating cost related information into the existing models used for Quantity Take-off.
At a basic level, BIM models are used to calculate the cost of all the materials involved in the construction by feeding the model with the unit cost for all materials. The major advantage for the team is to be able to have the budget automatically updated with any design change.
Currently 5D BIM models are prominently used for cost of the material calculation while efforts to incorporate the budget defining construction logic and cost of delay etc into BIM models such as cost of delay, labor cost etc. are in progress.
- Value & Cost Engineering
BIM is an iterative process providing the team with the ability to develop and analyze multiple design options and scenarios. By being able to have the cost estimation updating live with each scenario, the value engineering process using BIM Models is made more efficient and effective. - Life Cycle Costing (LCC)
Life cycle cost analyses the total cost of the construction project from Initiation through Demolition. Some of the important things to consider in this process are cost of construction, operation and maintenance of certain systems that define the building performance.
Building Information Modeling with 5D capabilities covering the project life-cycle, will enable the team to streamline the life-cycle costing process. 5D BIM models provide the capability to analyze the energy efficient of the systems with alternative design studies.
6D – BIM
As-built BIM Models embedded with facility management related information such as maintenance schedules, product manuals etc are considered as 6D.
6D – BIM models are considered to be rich with full building information accurately depicting the built project. Having BIM models developed all the way up to 6D defines the ultimate use of Building Information Modeling to its fullest potential. BIM Models representing the finished construction accurate in 3D along with the object level information such as specifications, warranty, operation and maintenance details are 6D.
BIM models with 6D information are used to integrate either directly or indirectly with an existing Facility Management system to feed the required data in the right format.
- Facility Information
The amount of information incorporated into the models at this stage is of various kinds and is more complex than 3d, 4d or 5d. It is important for the BIM teams to work directly with the facility management teams to understand the data formats and the level of detail required. During the operation and maintenance of the project, this data will help to monitor the building performance and also the carry out the maintenance activities as per the FM Manual. - Integrating BIM with FM
Project Facility Management involves several departments to carryout activities such as space management, operations management, asset management etc requiring different project information in various formats. Currently 3rd party tools are being used to help migrate BIM data to the existing FM system.
Bi-directional data link between BIM models and the FM system will benefit the project team in many ways.
NOTE:
This is a multiple-part series detailing the complete funtionalities and implementation process of Building Information Modelling (BIM).
Below are the other topics included in the series:
- A brief introduction to BIM
- How BIM can deliver optimum results
- In-House BIM developement V/S Hiring external consultants – Which is better?
- Top 5 areas where BIM can help realise a project’s full potential
To contact Voxel1 Solutions visit: www.voxel1.com