Technical standards for the development of BIM libraries

There are many standards for developing BIM libraries. However, they all pursue the same goal, unification and standardization in the development of libraries, project templates and work methodology. In recognition of this fact, we will try to present basic definitions in relation to existing standards, such as Revit Standards (gaining more and more popularity in Europe), ANZRS (Australian-New Zealand Revit Standard) and NBL-UK (National BIM Library in Great Britain). These standards are available to the public and anyone can read them.

Today, no BIM software, including Revit, can improve the entire lifecycle of a building in one large file or model. Therefore, the above standards are particularly focused on collaboration and communication, both within Revit and with third-party software (eg Archicad) and through the use of IFC.

To start a project in BIM, the designer must have basic work tools, such as:

• Project template – is an output / startup file that contains a number of settings such as:
  • levels,
  • displaying objects in views,
  • view filters,
  • print line width,
  • object styles,
  • basic materials,
  • building partition systems,
  • statements.

However, every advanced user of BIM software can independently expand and modify his template, adding to it, for example, new materials from the manufacturer (e.g. aerated concrete blocks), wall systems (full wall structure including all its layers, i.e. load-bearing layer, insulation thermal, membrane layers, finishing layers).

• Libraries – Any BIM project is only as good as the library / family used in it. We distinguish the following libraries:
  • System Families – Used to create basic building elements such as walls, roofs, and ceilings. They take into account the complete structure of the building partition, its layers, i.e. the load-bearing layer, thermal insulation, membrane layers, finishing layers.

• Load families – libraries that are:
  • created independently of the project and then loaded into the project, e.g. material definitions for cell blocks, stone wool, door and window libraries.

• used to create installable building components such as doors and fixtures.
• often a subordinate element of system families. For example, define the materials that make up the wall structure, thanks to which the wall is able to automatically calculate the U, R coefficient.

• In-place families – custom elements created in the context of the model.

Good quality BIM libraries greatly facilitate the work of a designer!

Because they enable him to quickly create statements, product specification and information exchange. For this, compliance with the standards is essential. Since the library is inconsistent with any standard, it is more of a problem than help. Let’s imagine that each manufacturer prepares a library, at his own discretion, creates his own individual parameters, and when the designer has to prepare a bill of materials, he has dozens of parameters that speak about the same thing more than once. If, however, the above manufacturers followed the standard, their values would always be collected under the same parameters, e.g. fire resistance, instead of being displayed in 5 different parameters, it would always be collected under the same parameter.

Here, the application of standards brings the most benefits to both architects and the manufacturers themselves. In addition, we must remember that construction project is a process in which many different companies work together. The BIM methodology was created so that all participants have access to the same information, which is why their unification in accordance with the standard is very important. Therefore, it is good to define the standard we want to work with at the very beginning of the project. This means that parameters, object styles, naming conventions, etc. must match. Content created according to the standard has a certain base quality. A building designer using this content can trust that the content will be seamlessly linked to the project template. The content will be displayed correctly in the schedules according to the view templates and correctly exported to IFC.

Whichever standard we choose, it is important that we stick to it. When preparing his BIM library, the producer should ensure the consistency and uniform standard of his objects. This will ensure better management of the product information base and facilitate cooperation with the architect. It is also important to understand the basic definitions used in the software so that the delivered library meets the expectations of the architect, e.g. a manufacturer offering:

• Aerated concrete blocks should build a material base in accordance with the manufacturer’s offer, taking into account dimensions and technical specifications, so that each material can refer to an individual code or group of products. The next step should be the preparation of building partition systems, e.g. joining construction blocks with mineral insulation boards, made of a very light type of aerated concrete.
• System lintels, columns, wreaths, etc. should be prepared as loaded Family objects, this will enable them to be inserted in the same way as windows or doors and will allow you building a list for each individual element.

BIM libraries / families can also have different levels of detail defined as accuracy standards. They function on two parallel dimensions, one concerns the accuracy represented by the geometry of the model and it is called “Level of Development” (LOD), and the accuracy of information carried by the element “Level of information” (LOI). Such a division made it possible to introduce standards of accuracy to the design methodology. These definitions are based on the standard prepared by the AIA (American Institute of Architects) called AIA G202-2013 Building Information Modeling Protocol Form.

Brief Description of LOD Accuracy:

• LOD 100 – a model element is represented by a symbol or a general approximate shape and approximate location
• LOD 200 – an element is represented by a symbol or a general solid, this accuracy allows for defining the required cubic capacity for objects. Possibility to correct functional and utility assumptions
• LOD 300 – an element of the model is represented by specific objects and systems, on the basis of the model, it is possible to calculate the total number and cubature, as well as make measurements. This level allows you to create preliminary analyzes to optimize, improve the quality of the model and verify the architectural qualities of the building. This accuracy can be compared to the accuracy of a construction project
• LOD 350 – an element of the model is represented by specific objects and systems, on the basis of the model it is possible to calculate the quantity and cubature as well as to make measurements and coordination with other elements. This is often the level at which the manufacturer, product specification and product geometry are already covered
• LOD 400 – the model element is represented by specific objects and systems along with assembly details and production information, on the basis of the model, it is possible to calculate the exact quantity and cubature, as well as make measurements and coordination with other elements. Similar to LOD 350 but with greater accuracy
• LOD 500 – a model element is represented by reflecting the real model, e.g. construction details.

From the manufacturer’s point of view, it is important to provide the most relevant information, but with a reasonable level of detail. In practice, the architect uses different levels of detail at individual stages of the project: concept, construction design and detailed design. Each time beter detailing the project.

However, information from the manufacturer may appear quite early. Therefore, not overloading libraries with excess information, but collecting the most important properties, is quite important, which makes it easier to work according to standard. Loaded families can also be refined using Specific Object Geometry (SOg). For example, at the very beginning, we can provide the Architect with a library (lintels, windows, etc.) with Generic Object Geometry – Gog, which is based on cubes, and then refines it by loading the detailed geometry.