Building Information Modeling (BIM), which is one of the most significant developments in the architecture, engineering and construction industry, is an approach that incorporates different tools and processes into design and provides opportunity to manage project data in a numeric setting. Unlike traditional 2-D design systems, BIM provides a 3-D representation which includes database storage mechanisms for the properties of all structural elements. In other words, BIM is based on elements that make up the structure and models the relation of these elements with each other.

The information level that should be included in the model elements is defined as LOD (Level of Development) numbers by different organizations and companies. Establishment of LOD tables for all systems and elements before the modeling starts carries out importance for the description of everything that the BIM model will include and exclude, for the determination of the level of information that the model includes, and for knowing what each personnel is responsible from. The 5 LOD levels that is usually defined in BIM projects are described below:

LEVEL OF DEVELOPMENT

LOD 100 = Conceptual Design Phase; It is the phase where the elements are modeled as masses. Model elements consist of 2D-3D mass forms, 2D symbols and written short notes.

LOD 200 = Design Improvement Phase; It is the phase where the predictive information about the number, dimension, position and direction of the model elements are described.

LOD 300 = Final Design / Documentation Phase; It is the phase where the certain information about the specific properties, details, number, dimension, position and direction of the model elements are described.

LOD 400 = Construction Phase; It is the process of construction of the building. It is also the phase where the manufacturing, setup, producing company information of the model elements and model number are added.

LOD 500 = Operation Phase; It is the phase where the building is opened to operation. It reflects the final status where the procurement information of the elements and the replacement part information is added.

These 5 phases made for the LOD description give the breaking points for the project needs. As such, it may be necessary to use and define different phases in the LOD table such as LOD 250 or LOD 350 as per the project needs. At this point, correct identification of the correct LOD phase and predefinition of the duties and responsibilities are important for interdisciplinary cooperation.

In order to provide interdisciplinary cooperation in the BIM system, many programs offer solutions in their software. It is important for the departments to use the same software or softwares that can communicate with each other directly and that are on the same version so that the work to be done can be applicable. Additionally, since work will be performed on a single model, care should be taken to ensure that the file sizes are appropriate for the current computer hardware.

Interdisciplinary incompatibilities identified during the construction phase (especially the incompatibilities of mechanical and electrical systems with architecture) is one of the main reasons for the emergence of BIM. With the transition to the BIM system, site errors have decreased by 41 percent and construction costs have decreased by 23 percent.  On the other hand, project durations have decreased up to 19 percent.  In addition to this, making use of Building Information Modeling provides advantages in different stages:

Benefits to the Owner in the Pre-Construction Phase:

• It provides possible cost and budget foresights in the concept, feasibility and design stages,
• Building performance and quality is improved,
• Owner satisfaction is increased,

Benefits in the Design Phase:

• Design is visualized earlier and more accurately,
• Changes made in the design reflects automatically to the 3D model,
• Accurate and consistent 2D technical drawings can be obtained in any design stage,
• Cost estimations can be obtained in the design stage,
• Since it provides coordination opportunities to all disciplines in the early stages, it prevents problems that may arise before they occur,

Benefits in the Construction and Production Phase:

• Pre-construction awareness of design mistakes, shortcomings and negligence minimizes the application mistakes, change orders and material, machine and labor losses,
• Margin of error in the quantities and cost calculations are minimized,
• Controlled cash flow throughout the project is provided and costs are effectively controlled,
• Durational deviations are minimized,
• Design changes in the construction phase can be quickly responded to,
• Supply is synchronized with design and construction,
• By minimizing uncertainties, risks assumed by each party are made clearer,
• Construction control quality is increased, therefore the stock of quality building is increased,
• Lower energy consumption and less waste production during construction is provided,

Benefits in the Phases After Construction:

• The process of transferring and operating the facilities is improved,
• Facilities are managed and operated more efficiently,
• Integration with facility management and operation systems is provided,

The use of BIM applications in the construction industry, which was initiated in 2002 by the construction industry in the U.S., has reached 75-80% in the US and 40-50% in Europe. Especially, the applications are used extensively in England and Denmark, where the public support is strong. On the other hand, BIM usage in Turkey is in the start-up phase; and in order to make progress, the role of all parties (i.e. project owner, project management company, designer and contractor) is huge. However, the most important role to accelerate widespread usage of BIM in Turkey belongs to the governmental institutions who can provide incentives by preparing laws and regulations.

Ayda Atak Argun, Architect, LEED AP