AACE Guide

AACE International Standards & Frameworks

Your comprehensive guide to AACE International's cost engineering standards, Total Cost Management framework, estimate classification systems, and professional certifications. Understand how these globally recognised standards apply to Australian infrastructure projects.

About AACE International

The Global Authority in Cost Engineering and Total Cost Management

AACE International (Association for the Advancement of Cost Engineering) is the world's leading professional organisation for cost engineers, cost estimators, schedulers, project controls specialists, and related professionals. Founded in 1956 as the American Association of Cost Engineers, AACE has grown into a truly global body with members across more than 100 countries and local sections spanning North America, Europe, Asia-Pacific, the Middle East, and Africa.

AACE's mission centres on advancing the discipline of cost engineering and total cost management through technical research, professional development, certification programs, and the publication of industry-leading standards and recommended practices. The organisation's work underpins how projects are estimated, budgeted, scheduled, and controlled across virtually every sector of the built environment, from process industries and mining through to transport infrastructure and defence.

1956
Founded
10,000+
Members & Certificants
120+
Recommended Practices
8
Certifications

Explore the AACE Guide

Navigate through each section of our AACE guide to understand the standards, frameworks, certifications, and recommended practices that define international best practice in cost engineering and project controls.

AACE Estimate Classification System

AACE's estimate classification system (Recommended Practice 18R-97) maps estimate accuracy to the level of project definition. Estimates progress from Class 5 at concept screening through to Class 1 at full definition, with tightening accuracy ranges at each level.

5

Class 5 - Concept Screening

Order-of-magnitude estimates prepared during early concept screening when project definition is minimal. Used for initial feasibility assessment and strategic planning decisions.

Project Definition
0% to 2%
Accuracy Range
-20% to -50% / +30% to +100%
Typical Method
Parametric / Capacity Factored
4

Class 4 - Study or Feasibility

Preliminary estimates developed during feasibility studies when basic engineering and scope definition are underway. Used for project screening and preliminary budget approval.

Project Definition
1% to 15%
Accuracy Range
-15% to -30% / +20% to +50%
Typical Method
Parametric / Factored
3

Class 3 - Budget Authorisation

Semi-detailed estimates prepared when engineering is sufficiently advanced to support budget authorisation and funding commitments. Forms the basis for project sanction decisions.

Project Definition
10% to 40%
Accuracy Range
-10% to -20% / +10% to +30%
Typical Method
Semi-Detailed / Mixed
2

Class 2 - Control or Bid/Tender

Detailed estimates prepared from substantially complete engineering deliverables. Used for cost control baselines, contractor bid evaluation, and detailed project budgeting.

Project Definition
30% to 75%
Accuracy Range
-5% to -15% / +5% to +20%
Typical Method
Detailed Unit Cost
1

Class 1 - Check Estimate or Bid/Tender

Definitive estimates based on complete or near-complete engineering and procurement data. Used for final check estimates, change order pricing, and claims resolution.

Project Definition
65% to 100%
Accuracy Range
-3% to -10% / +3% to +15%
Typical Method
Detailed Bottom-Up
Cenex Expertise

How Cenex Applies AACE Standards

As a Queensland-based cost estimating and engineering consulting firm, Cenex integrates AACE International standards alongside Queensland's PCEM framework to deliver estimates that meet both local compliance requirements and international best practice. Our team applies AACE methodologies to ensure clients receive robust, defensible cost estimates regardless of project type or procurement model.

Our AACE-Aligned Capabilities

  • Estimate Classification: We classify all estimates using AACE's five-class system, ensuring stakeholders understand the level of accuracy and the maturity of project definition underlying each estimate.
  • Total Cost Management: Our approach aligns with AACE's TCM Framework, applying integrated cost management from strategic asset planning through to project delivery and operations.
  • Risk Quantification: We apply AACE Recommended Practices for probabilistic risk analysis, including Monte Carlo simulation and risk-adjusted contingency determination.
  • Earned Value Management: For projects requiring cost and schedule performance tracking, we implement AACE-compliant EVM systems that provide early warning of budget and schedule variances.
  • Professional Standards: Our senior cost estimators hold AACE certifications including CCP and CEP, ensuring our work reflects the latest industry standards and technical knowledge.
  • Dual Compliance: On Queensland infrastructure projects, we map AACE estimate classes to PCEM phase requirements, delivering estimates that satisfy both frameworks simultaneously.

AACE standards for Australian infrastructure

Whether your project requires AACE-classified estimates for a mining operation, an energy facility, or a transport corridor, Cenex brings the expertise to deliver cost estimates that align with internationally recognised standards and Australian regulatory requirements.

Need AACE-Compliant Cost Estimates?

Cenex delivers cost estimates aligned with AACE International standards for infrastructure, resources, and energy projects across Australia.

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