Reaching project target costs is a whole lot easier with 5D model-based cost estimating. 5D model-based cost estimating links and maps model elements and associated construction quantities to develop a project cost plan. 4D construction sequencing brings the element of time or schedule to the 3D BIM model; 5D brings the element of cost. This cost estimating method is an effective way to work together with the owner and project stakeholders, leveraging a wealth of information and experience from the model to the project in a visually communicative way. Use of 5D model-based cost estimating may still be a fairly new practice for some people. However, I am pleased to report that we’ve had great success using model-based estimating over the past 10 years. This article aims to illustrate how 5D model-based cost estimating can be successfully applied on your next project.
Bay Area Project, integrating the model with cost database using Innovaya and Timberline estimating software
Concurrent Scheduling and Cost Estimation
5D model-based cost estimation occurs concurrently with VDC during the preconstruction 4D construction schedule sequencing phase. The 4D model-based project schedule integrates a series of multi-disciplinary performance models, which includes the building or structure, manpower, workflow sequences and processes, and overall organization of the design and construction. This effort requires continuous referencing and analyzing the project model to determine material quantities, schedule milestones, project cost, material quantities as well as identification of potential project risks. All of these variables are carefully considered throughout Building Information Modeling (BIM).
Bay Area Project, 4D Model-Based integrated construction sequencing - Linking the model with construction schedule.
Cost Estimating and Cost Monitoring in Real Time
Model quantities and dimensional information are directly linked and mapped to the estimating database. Cost database integration allows you to provide real-time cost plans. While this may sound really simple, it must be said the model needs to be properly developed in order to be useful in deriving quantities. Modeling content and level of accuracy needs to be discussed between parties (model author/5D users) prior to modeling. It is essential to communicate early on with the design team about relevant design intelligence that be used to accelerate the estimating process which will allow for an accurate cost estimate. 5D model-based estimating also leverages estimating department expertise , in effect a knowledge base of cost and time variables the BIM model can draw upon.
Accurate cost estimation coupled with a clear representation of accrued cost across each project phase allows for a significant and positive impact on construction management. In addition, 5D BIM provides intuitive feedback on cost saving strategies (value engineering and constructability review) and cost predictability.
Responding to design cost option studies, design changes and value engineering requested by owner, and architect is commonplace. Timing is of the essence in the decision-making process; it is important to prioritize the response to these requests. 5D model-based estimating allows you to immediately performing estimate updates without delaying the decision-making process. In my experience, it’s quicker to visualize, discuss, and approve a change on-the-fly using the model than receiving sketches from the architect via email and hoping to get back with an instant answer.
For example, let’s suppose you need to have a very dynamic discussion with the design team and owner about the skin system and the geometry of the building that may be running 5 to 10 iterations per day at the conceptual phase. This provides you an opportunity to act quickly by delivering proactive and predictive preconstruction services. In order to optimize the effectiveness and efficiency of the 5D model-based cost estimating process, you must be able to leverage the cost estimator’s expertise and intuitive experience. It is important to know how much control and level of certainty you have when relying on the model to run your estimate. If you know how the model was properly created and monitored, then you should be able to instantly run and/or update your estimate while sitting at the table with the architect and/or owner.
Design Change Management
As you know, design changes always occur during design development. Many questions regarding the cost impact of design changes will surface from both architect and owner. It is important to track these changes every day. You are too late if you report the budget cost impact at each cost estimate milestone. Design changes must be communicated to the entire team and monitored daily for negative/positive impacts on the budget or project target cost. Visualizing, discussing, communicating, approving and updating the model will ultimately accellerate the decision-making process.
- An organized in-house database with cost and pricing information, labor productivity rates, crew composition data and subcontractor Key Performance Indicators (KPIs).
- Provides the owner with instant feedback on schedule and budget change impacts
- Enables cost-loaded schedules, detailed analysis of project risks, and accurate cash flow forecasts.
- Detects conflicts easily allowing for early mitigation. Costs of the construction can be easily viewed, monitored and managed.
- Ability to provide multiple iterations of evolving estimates for the Owner, which can be quickly compared to the target cost.
- Allows the ability to evaluate how a change in design may influence the budget and scheduling of a project.
- Allows for more productive decision-making by evaluating multiple cost estimates with objective of reaching a project’s target cost.
- Ability to evaluate areas of the building which add to the total cost and how.
- Compare cost plans with the original budget, at any stage and any point of time.
- Ability to see changes and make decisions.
- Understand and focus on design decisions that have significant impact on involved costs.
- Predict costs.
- Evaluate the impacts of the sustainable design strategy in terms of costs and projected energy savings.
- Eased access to detailed information about costs and schedules enabling team efficiencies.
- Project stakeholders are able to work more collaboratively to achieve timely project delivery, cost efficiency and quality.
- Improved functionality and cost estimate accuracy throughout a project’s lifecycle.
- Instead of evaluating and estimating for all elements at an equal level, experts identify the building elements responsible for driving up total project costs.
- Building elements are analyzed and a more focused approach toward design and cost is followed.
Have you engaged in 5D BIM model-based cost estimating? What was your experience? Please share your story with us in the comments section!