Cost estimating (5D BIM) is a process in which BIM can be used to assist in the generation and collection of accurate quantity take-offs and cost estimates throughout the life-cycle of a project: advantages and opportunities
BIM, Building Information Modelling, is a technology that allows designers and quantity surveyors to have precise and detailed information to estimate the costs of a project, while reducing the variability of cost estimating. Basically, 5D BIM is a BIM methodology dimension that explicitly corresponds to the cost estimating information relating to a building asset.
In a three-dimensional model, the economic variable is introduced to estimate the costs of a project, in order to control and estimate costs (by assigning parametric values, such as unit prices, to several objects and elements). By using the information model of a building rather than just drawings, it is possible to generate quantity take-offs, calculations and measurements directly from the model.
5D BIM links costs and estimating processes directly to 3D models that are created by a designer. When including cost analysis in the BIM ecosystem, it is possible to speed up and optimize the entire planning phase of a building, also with regard to the financial aspects. This aligns with the possibility of quickly assessing the costs relating to different construction and planning solutions.
The information is always consistent with the design, and when a change is made to the project, for example resizing a window, all the relating documents and construction drawings, as well as all the inputs, calculations and measurements are updated automatically.
The benefits of 5D BIM
Preparing a bill of quantities is a complex task that should not leave any room for errors. Here are the basic steps that need to be followed to prepare a BoQ correctly:
- describe work items precisely
- acquire quantities
- organise the measurement data in a logical and chronological sequence
- assessing materials, rules and units of measurement
The more accurate the measurements the better in order to avoid the risk of making pricing and project cost errors. Putting this into more practical terms, only a digitized process can tend to guarantee an accurate correlation between the 3D Model entities and the relating cost items or Price Book elements.
So what are the advantages of having a full integration between the BIM model and the 5D Construction Cost Estimating:
- total control on cost analysis: every single detail of the bill of quantities is traced out and monitored, assuring measurement accuracy and cost control for construction firms
- fast quantity surveying: preparation of an accurate model-based quantity survey means increased efficiency and optimized workflows within the BIM process design teams
- quality of work: greater control and processing speed leads to better productivity that turns into cost savings for the building contractor and design firms.
Precise cost estimating information also positively takes part in the decision-making and planning processes: collaboration among all building process parties is widely becoming a BIM prerogative because it allows everyone involved to have the project costs under control even when making project adjustments based on specific client requirements.
The employment of 5D BIM technology leads to greater precision and predictability in analysing the project costs, variations in quantities and materials, equipment or labour: the integration of BIM with 5D BIM simulation models, in practice, allows the development of more efficient, affordable and sustainable buildings.
The implementation of BIM in the cost analysis through all the phases of the building process, provides with precise and detailed information, thus allowing engineers to make correct and informed decisions. With a clear vision of a project, engineers make the best decisions during the first stages of its development, thus reducing the need of re-engineering parts of a building during its construction.
Thanks to these obvious advantages, we can observe how many different technologies are starting to become part of the BIM process, such as cloud computing, AR and VR, mobile apps etc.
These technologies are becoming part of the AEC industry, providing brilliant results and allowing more efficient decision-making strategies.
5D BIM in Edificius: the automatic bill of quantities from the 3D BIM model
Edificius, the software for architectural BIM design, allows quantity surveyors and architects to automatically obtain a dynamic bill of quantities from the BIM model, thanks to the integration with PriMus.
With the PriMus environment active, a simple drag & drop of a price list item directly to a BIM entity (wall, window, beam, column, etc) allows the user to associate cost information with dynamically acquired metric data deriving from the entity itself. Any variations to the model cause the metric data to change and therefore the relating cost also changes together with the project’s total cost.