ASHRAE Standard 209-2018

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In 2018, ASHRAE published the first version of Standard 209 Energy Simulation Aided Design for Buildings Except Low-Rise Residential Buildings. Its purpose is to “Define minimum requirements for providing energy design assistance using building energy simulation and analysis”[1]. The committee that wrote Standard 209 sought “to define reliable and consistent procedures that advance the use of timely energy modeling to quantify the impact of design decisions at the point in time at which they are being made”[1].

The standard defines the concept of modeling cycles, which are energy modeling activities with a specific purpose, applicability and analysis approach.


For a project to comply with Standard 209, the design process must meet general requirements, which include four specific activities, and must also include at least two modeling cycles. One of those modeling cycles must be #3, load reduction modeling.

ASHRAE Standard 209-2018 compliance

General Requirements

Each project is required to include the following as part of the design process:

  • Climate and site analysis
  • Benchmarking
  • Energy charrette
  • Establish Energy Performance Goals in the owner's project requirements

Modeling Cycles

General modeling cycle requirements

  • Energy Baselines and Goals
  • Input Data
  • Reporting
  • Quality Assurance
ASHRAE Standard 209-2018 Modeling Cycles
Design phase Number Modeling Cycle
Conceptual design 1 Simple box modeling
2 Conceptual design modeling
Schematic design 3 Load reduction modeling (required)
4 HVAC system selection modeling
Design development 5 Design refinement
6 Design integration and optimization
Construction documents 7 Energy simulation-aided value engineering
Construction and operations 8 As-design performance
9 Change orders
10 As-built performance
Post-occupancy 11 Post-occupancy energy performance comparison

Additional Resources

  • Architect’s Guide to Building Performance from the AIA discusses how to integrate BEM into the design process and provides a good overview of the requirements of Standard 209-2018.
  • ProjectStasio is a website that provides example BEM graphics, which can be filtered by Standard 209 modeling cycle

Links to external websites are provided as a convenience for further research, but do not imply any endorsement of the content or the operator of the external site, as detailed in BEMcyclopedia's general disclaimers.


  1. 1.0 1.1 "ASHRAE Standard 209-2018".
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