BIM - Building Information Modeling
- ▪ Introduction
The term Building Information Modeling (BIM) has widely established for the integration of formerly separated skills in planning, construction and operating data in from now on one holistic digital modeling during the whole lifetime of a project. The once only graphical, now in addition attribute based software system creates a precise, three-dimensional building model including all necessary alphanumerical information during design and construction process as well as operating time of a building.
In addition to all mere geometry data for the preparation and production, analysis and optimization, as well as relevant for future life period, operational data is collected in a centralized database and linked to all members of the project and user team.
All parties involved in construction and further operation period, e.g. users, architect, engineers for structural and building services, construction companies, process and logistics planners, can push in and draw out all relevant information regarding the planning and life-cycle
stages in a central building data model. Thus any Changes made during the planning phase are automatically reflected in all affected areas such as Floor plans, sections, elevations, 3D isometric drawings and schedules are promptly updated.
- ▪ Presentation of design variants
The preparation and presentation of design alternatives as well as herewith associated comparison of construction costs is a common practice in the complex planning scenarios. In conventional project organisation planning and management of variants usually was very time-consuming and expensive, and often led to redundant plans. Using building information modeling, it is possible to develop important design alternatives in the same building data environment, and parallel examination of detail aspects leading to decision results. Each option can be modeled in advance and, depending on depth of the relevant information (e.g. topography shifting land masses, requirement of components) possible changes affecting the project are automatically included in all planning options. This saves time, reduces faults and keeps all relevant project data consistent.
- ▪ Optimization of topography
With the help of modeling tools within the BIM software, it is possible to connect numerical information of the terrain profile import to survey protocols and applications in civil engineering from the project and automatically generate a three-dimensional terrain model. For land with a steep slope, earth mounds, trenches, etc. earth movements can be exactly measured during the planning phase. Thus later site works e.g.height adjustment, erosion or landfill will be at least minimized and unnecessary costs will be avoided. In addition to the temporal advantage of three-dimensional terrain modeling, this method provides a much higher accuracy compared to manual calculation based on a series of ground sections and interpolation
- ▪ Parametric
The virtual building information model consists of parameterized elements that include a variety of building data, as well as the relationships to other objects. Example may be that a simple wall drawn is not assigned to an overall height in meters, but the 3D model is associated with the upper edge of the layer above. Later during a change in planning the new floor height adjusts all relevant walls and any other objects that are attached to this level. The update for all affected documents such as floor plans, sections and elevations is then performed automatically.
- ▪ Areas and mass analysis quantity surveying
Schedules offer not only the traditional planning documents, a further view of the information of the building information model. This is the numerical representation of all elements present in the model in the form of tables and reports. The user has the opportunity to consider the relevant information as required and change. For instance it is possible to sort façad's subcomponents after diverse, also self-generated characteristics as fire resistance, price, floor, opening directions, etc. Areas and surface areas can e.g. are presented in the form of a clear space book. Values for the area or volume to be automatically calculated based on the geometry. All non-bound to the geometry information, such as Room number and name space can be adjusted by the user clearly in a table. In addition to the rooms and spaces are also the components of the architect, building engineer, structural engineer and factory and logistics planner for evaluation in schedules available. Production elements are assigned automatically when you insert the rooms or areas,
and can be detected in space books or equipment lists.
- ▪ Construction processes and virtual construction site
Due to the usual time pressure besides presentation of design variants trouble-free construction progress of a project is a mayor target in project organisation. Thus for planners and for performers, it is important to coordinate precisely the site operations in terms of multi company logistics and construction, in order to avoid unnecessary conflicts and overlaps. Building Information Modeling allows by means of assignment of construction parameters to relevant object a temporal virtual building process before the future site works. Already before the first sod, individual construction phases, as well as complex construction intersections may be simulated.
- ▪ Daylight simulation
The BIM technology also enables to create DIN compliant daylight and artificial lighting calculation routines, thus allowing for both visual impression of light and shadow conditions as well as quantitative evidence of the of virtual measurement points in an early design phase.
In case of a daylight simulation the 3D BIM model of the building geometry and material attributes are transferred into a daylight simulation software, transmitting specific information about the location and orientation of the building from the building information model automatically. After reading the site-specific weather information and definition of the simulated daytimes or time intervals DIN-compliant evaluations of e.g.animated shadow patterns or false color representations can be calculated and visualized. Impairments in the workplace due to unwanted glare resulting from direct sunlight are detected early and appropriate measures in façade construction may result in an early design phase.
- ▪ Artificial light simulation
In the case of artificial light simulating the building information model is supplemented by luminaire manufacturer information (e.g in Dialux or IES format, internationally accepted data formats), to describe the light distribution of luminaires. Using a "light meter", a user can chose a defining grid for virtual measurement of illuminance, checking area to be examined according DIN as well as simulating various lighting concepts. Thus, both individual areas and an entire building can be simulated realistically, analyzed, and optimized for the respective requirements. A costly and time-intensive sampling of building and site can therefore be omitted in most cases and requirements for good lighting may be considered in the further planning. Figure 5 shows a hall interior with artificial illumination of 500 lux, the specific hall spotlights were from the product range of a luminaire manufacturer (e.g ERCO, Zumtobel) virtually mounted in the ceiling.
- ▪ Energy analysis and optimization
Even seemingly simple design decisions in the early planning stages, such as orientation of volumes on a property, can have a significant impact on the future energy balance of a building, and cause lifetime (too) high operating costs for heating / cooling. Building Information Modeling allows architects and engineers to check energy performance aspects of design in a very early planning phase. The virtual models for the simulation of energy aspects are dynamic specific 3D tools like e.g. IES Virtual Environment, Autodesk Green Building Calculation, TAS, Design Builder, using the architects 3D digital BIM geometry and material data.
- ▪ Visualization
Apart from sometimes rather sober simulations, analyzings and evaluations, the visualization is an important tool for conveying design ideas to clients as well as showing how technical systems and processes coincide with architecture of the building structure. Shaded representations of the data modeling with simple building material representations are current state of the art of BIM applications, in particular enabling users vivid impression of the virtual model during design. Moreover little extra effort allows for impression of photo-realistic images , camera moves by choice and walk through animations in and around the building. Various BIM application offer valuable tools for photo-realistic impressions, which provide good results with a few settings in a short time. Alternatively, the market also offers high-end applications such as 3D Studio Max or Cinema 4D.