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# Parametric Estimating 2024: A Comprehensive Guide to Accurate Project Costing

In the world of construction, getting estimates right is crucial. That's where parametric estimating comes in. In this article, we'll discuss how parametric estimating works and explore its impact on enhancing construction professionals' ability to create more accurate plans and make informed decisions for their projects.

## What Is Parametric Estimating in Construction?

Parametric estimating is a statistical approach to estimating project costs, time or resources. It differs from other common construction estimating methods, by using data from similar projects to identify correlations between quantifiable project aspects and outcomes. This method uses key project parameters, like square footage and building types to create mathematical models that predict outcomes — helping to identify cost drivers for better decision-making.

For example, let's consider estimating the cost of building an apartment. In parametric estimating, stakeholders and estimators analyze past project data, particularly comparing building size (measured in square footage) with construction costs. This helps them make more informed decisions between scope, schedule and resources for the cost of constructing a new apartment building.

Let’s say we want to build a four to seven-story apartment that is 74,500 square feet and has five stories with a story height of 12 feet. Using the parametric methodology and comparing different wall and framing types, you could expect the cost of that apartment complex to be between \$18.4 million and \$22.6 million.

## The Parametric Estimating Process

The parametric estimating process involves three key steps: determine project parameters, data collection and create a project model. A solid starting point in the process is to use a work breakdown structure (WBS), which helps break down the project into manageable work or task packages. By examining each of these steps, we'll uncover the inner workings of this process and gain insight into how it brings together different project components to create cohesive and accurate forecasts.

### Step 1: Identify Project Parameters

The success of any construction project hinges on accurately estimating costs and timelines. To achieve this, the first step involves identifying the quantifiable characteristics or parameters that will form the basis of your estimates. These parameters are unique to each project.

Here are some key parameters to consider in construction estimating:

• Square Footage: The total area of the building affects material quantities, labor hours and overall project cost.
• Building Type: Residential, commercial, industrial, institutional and other classifications introduce different construction requirements that impact costs and timelines.
• Material Costs: Fluctuations in material prices can significantly affect the project budget.

### Step 2: Conduct Data Collection and Analysis

Gathering comprehensive, high-quality data is crucial for establishing a solid foundation for cost estimation. Key actions in this step include:

• Obtain historical data from:
• Internal project databases
• Market data
• Specialized cost estimating software
• Prepare the data to:
• Ensure the information is accurate and consistent
• Utilize statistical models to:
• Analyze the relationship between identified parameters and project outcomes

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### Step 3: Develop a Parametric Model

Here, the data analysis comes into play. Based on the identified cost drivers (parameters) influencing project costs, a suitable formula or algorithm is chosen. This formula becomes the heart of the parametric model.

### Building the model:

1. Software Selection:
- The choice of software depends on the project's complexity.
- For simpler models: Spreadsheets can be effectively used.
- For more complex models: Specialized software offers advanced features that might be necessary.
2. Formula Integration:
- The chosen formula is incorporated into the model.
- Spreadsheets: Utilize embedded functions or equations.
- Dedicated software: May have specific tools, such as RSMeans Data Online, which provides detailed cost information for various types of construction projects. Explore RSMeans Data Online for estimating square foot costs and more.
3. Parameter Definition:
- User inputs for the identified cost drivers are established.
- These might include project size, material costs, labor rates or any other relevant factors.

Let’s see how this may work: We’ll use our four to seven-story apartment example from above. In this scenario, we have three quantifiable parameters: total square footage (area), story height and stories. If we were to break the total cost down to a per-square-foot cost, it would be about \$247 to \$303 per square foot for a building with similar parameters. This figure is a valuable starting point, and as the project progresses and specifics like materials, amenities and overall designs are finalized, a more detailed cost estimate should be developed.

Parametric estimating may not capture the economy of scale in construction, especially for significant parameter variations.

## How Parametric Cost Estimation Can Help

Parametric estimating offers a data-driven approach to cost estimation, leading to improved project decisions throughout the critical stages of preconstruction and design development. By leveraging historical data, it generates more precise cost forecasts, enabling:

• Realistic Budgeting and Risk Management: Early and accurate estimates promote efficient resource allocation, avoiding cost overruns and facilitate proactive risk management through continuous monitoring against benchmarks.
• Informed Feasibility Studies: Analyzing project parameters alongside historical data allows for informed decision-making during feasibility studies. This ensures project viability and efficient resource utilization by identifying potential bottlenecks early on.

## Key Benefits of Parametric Estimation

While improved accuracy is a cornerstone of parametric estimating, its advantages extend far beyond providing a more precise picture of project costs and timelines. Here's how parametric estimating empowers construction professionals throughout the project lifecycle:

• Enhances Accuracy and Reduces Risk: Data-driven estimates minimize the risk of overruns and project delays by providing more realistic cost predictions.
• Improves Project Control and Streamlines Workflows: Realistic budgets and efficient resource allocation lead to greater control over project finances.
• Empowers Data-Driven Decision Making and Competitive Advantage: Historical insights empower strategic choices for project success, leading to a competitive advantage through accurate estimates for competitive bidding or ability to secure funding.

## The Future of Parametric Cost Estimating

The future of parametric estimating is even brighter with advancements in data collection and analysis tools. These tools will allow for the seamless integration of even more diverse data sources, including existing real-time project feeds and external market trends. By embracing this data-driven approach, construction professionals can navigate project complexities with confidence and consistently achieve optimal outcomes.

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