The HBIM topic has recently gained a lot of attention: what is HBIM and what are the advantages resulting from the application of this new methodology?
Historical buildings represent the history and identity of our societies and communities.
For this reason, the conservation of historical buildings, made through energy refurbishment or retrofit and restoration works on existing buildings, is a crucial phase within their lifecycle.
The possibility of applying BIM technology to the historical heritage (HBIM) is an interesting challenge both in the field of 3D modelling and in the management / enhancement of the building architecture.
The main challenge is relating to modelling, as it is necessary to develop simple methods in order to obtain BIM models that guarantee, at the same time, accuracy, precision and quality of representation.
Furthermore, the model should be enriched with data and information that are not purely geometric, such as historical information, analysis of degradation or deformations, etc.
What is HBIM?
The term Historic Building Information Modelling, abbreviated as HBIM, was first used in 2009 in a scientific article by professor Murphy of the Dublin Institute of Technology.
This term indicates a new way of modelling existing buildings, using a BIM process that would produce intelligent models containing and managing information. Such models are obviously relating to project components and include their geometric and identifying information, and all the physical properties that best describe them.
The first attempts to create a BIM model of an existing building are linked to historical or monumental types of building. The aim was to generate a database where to include models created to be inserted and relating information to be used. Information such as simple geometric reconstruction of volumes or thermal analyses, etc.
HBIM is therefore a process applied to existing buildings, whether they be monuments or simple dwellings of the 1950s, greatly increasing the potential of BIM technology! HBIM can also be applied to existing building models, not only in terms of digital and geometric 3D reconstruction, but also as a methodology involving intelligent models with added information.
Basically, HBIM does not define a new type of designing, but it explicitly defines a way of working together with its applications. It is a technology that allows to reproduce an existing building and to create a model that can simulate its actual construction and that, in the end, provides most of its features in the most feasible way.
With HBIM, a sort of “reverse engineering” is applied to existing buildings. When a building is modelled, the procedures that led to the construction of that particular kind of building are then analysed, simultaneously improving the modelling process itself.
HBIM modelling starts from a survey: usually a digital survey that is achieved by using tools like a laser scanner or a camera for land photogrammetry. The so-called point clouds, sets of points with defined coordinates in space, are thus obtained. These points contain geometric and colorimetric information (their coordinates are known in a reference system), as each point is associated with a corresponding colour obtained from a photo taken by the digital tool during scanning.
The objective of HBIM is mainly obtaining BIM models of existing buildings, consisting of intelligent objects that contain information of any kind that can be updated, replaced and added. Furthermore, although each building is unique, parametric objects can be used for other similar buildings, because they have values that can be modified according to well-defined parameters and that are therefore adaptable to specific cases.
HBIM current state and perspectives
If BIM is at present times still unknown to many technical experts, there is even less awareness about HBIM. Nevertheless, efforts to integrate it are ongoing, creating larger databases of buildings’ parts, architectural elements, even entire buildings and building complexes.
As a matter of fact, university reasearch institutes are specifically trying to demonstrate that BIM applied to existing buildings could facilitate the conservation and management of the built heritage.
Today we know that, starting from a point cloud with a certain resolution, it is possible to create an intelligent and parametric model that will contain the highest number of information relating to the building.
This process currently takes a long time to be completed, because many BIM tools have not originally been created for modelling an existing building, but mainly for new constructions. Ongoing research is analysing new ideas and procedures in order to make the whole flow of operations fast and automatic. Starting from the point cloud to reach the building’s final model, the operations are carried out without losing too many details and information.
The objectives that HBIM sets mainly refer to a strategic choice in line with the direction that the construction market is taking: allowing coordinated data and information management between various technical experts and optimizing resources and costs.
All this leads us to conclude that BIM creates efficiencies not only for modelling existing buildings but also for designing new ones. In the future it could be a strategic tool, especially for countries that have an enormous existing building heritage and historical, monumental and architectural values.