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Date: 2017


Team: Amílcar Ferreira


Software: Revit/API




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BIM has become the leading method for representation, interdisciplinary collaboration and management through all construction trades.


Several essays demonstrate the relevance of the BIM method in all project phases. In many countries BIM has become a mandatory practice for projects regarding the public sector. The presence of BIM has become unavoidable and undeniable.


However, the rigor, the accuracy, and the detail of BIM tools come at the expense of the flexible and abstract interface needed for form finding in the architectural sketch stage.


Despite the available 3D modeling functions, BIM tools are based on 2D projection drawings. All 3D geometries are modeled from their planar projections. Modeling on 3D space is limited and often impossible, 3D views are more oriented to visualization than they are for modeling. This concept seems contradictory and penalizes the use of BIM tools phase to other 3D CAD software, the latter being more adapted and intuitive to the form finding.


While BIM software allows to parameterize every building component ( wall, roof, door, etc.) it lacks a component to represent and parameterize a building as a whole.


Such category must include all type of geometric and analytic parameters. Also it must define rules for the interaction between each instance and other objects in its context. With this tool we aim to add an easy and intuitive way to sketch ideas and diagrams to a BIM interface.




In order to develop this tool we choose Revit, as BIM software. The tools to be presented were developed with API, .NET and the samples found in the Software Development Toolkit (SDK)


In REVIT, there is some hierarchy in component properties: construction objects are classified into categories, families, types and instances. If you are not familiar with these terms please go to : http://help.autodesk.com/view/RVT/2014/ENU/?guid=GUID-2480CA33-C0B9-46FD-9BDD-FDE75B513727


This hierarchy is fundamental to understand parametric drawing on REVIT. Each instance or element drawn on REVITs interface includes in itself all inherited information. This information, in the form of parameters, allows us to automate the quantification, analysis and representation and also to instantly change the properties of an object.

To develop a "Building" category we have carried a non-exhaustive research on building typologies, we have been inspired by projects in the following fields: office building; and medical building. For future essays, new typologies can be identified and justify a new family building. We have searched for the lowest common denominator to all typologies and then we isolate its proprieties. This element is the base for our first Building family, we will call it “Layer Building.”



The"Layer Building" family is composed by vertical layers, each one contains three fundamental properties: nature, illumination, function. Nature determines whether it is a circulation area or a "useful" area. Illumination determines whether the zone is exposed to sun light or not. The function determines for each sub-element the zone of the functional program it belongs to.


Each sketch becomes more than an abstract 2D/3D representation, it will also include all the information inherent to the "Layer Building" family to which it belongs.




The user has the possibility to edit and create types according to: the number of layers, their three fundamental parameters and their thickness.


The type of family "Layer building" should be constructed according to the functional restraints from the program it will host.



Each instance of the "Layer Building" family has instance parameters, such as height, level constraints, area and volume.





The "Building" category is able to be separated into elements. This feature also exists on other Revit System families (floors, walls, roofs) and allows the user to divide an instance from the "Building" category as many times as necessary. Each element is defined by instance parameters (for example: zone name, room name, area, volume, depth, height, etc.) it also inherits the parameters nature, illumination and function from the parent family instance and layer.


In order to automate this step we have developed one recursive algorithm that separates the instances of the building family according to the functional program of the building. This tool offer us different methods of subdivision according to the architect input: subdivision by zone or by room; random subdivision or according to an order of proximity given by a unique sequential code of each room.



Each element result of a “Layer Building” family instance division can be transformed, however they will always be referenced and conditioned by the parent family instance and layer.




Each BIM category includes in its programming the rules that determine its behavior phase to other elements. For example, a door can only be applied to a wall; two walls cannot overlap; a room separator and a wall cannot overlap. When the designer forces an inconsistent action between two elements, the software displays a warning message and saves the warning in a report that is accessible to the user.


This principle has been applied to the building category. At first we modeled an abstract mass that translates urban rules for the site, like a bounding box representing the space that the building can occupy. We call this mass "Capable Volume". Secondly, the tool gives us warnings if the drawing is invalid, that is, when an instance of the Building category intersects the Capable Volume. This tool avoids going back and forth between the different projection views and 3D to check if the drawing respects the pre-established physical restraints.





This study is being applied in the practice of the studio Michel Rémon & Associés (MR&A) since 2016. Its development will be progressively tested and re-evaluated amongst architectural projects in sketch phase.


The MR&A it’s a relevant case of study because it is an agency with a diversity of professionals. MR&A teams are composed of architects who have followed the transformation of their working methods from manual drawing to the implementation of CAD and BIM, as well as architects with professional experience working on digital tools.


Recognized for its functionality that follows many projects in the complex program, the MR&A has built a design process which is consistent and transversal to the tools (either manual drawing or CAD).


The users were able to use all the features in multiple projects, the learning time was reduced and the manipulation was considered, flexible and intuitive.


We will keep innovating and developing new tools to improve conceptual design on BIM.