ANSI/ASHRAE Standard 209-2018, Energy Simulation Aided Design for Buildings Except Low-Rise Residential Buildings is the product of a half-decade of inertia within the building design and construction community toward leveraging energy modeling a design tool through a project.

Standard 209 outlines the minimum requirements for providing energy design assistance using building energy simulation and analysis. To this end, the standard defines a range of minimum criteria from energy modeling requirements, to modeler credentials, to data reporting.

Adoption of the integrated framework offered by Standard 209 will better ensure the utility and accuracy of building energy modeling on a project by requiring project teams to adhere to stringent and standardized requirements.

The standard builds upon the notion of curating and refining a building energy model from conceptual design all the way through postoccupancy a concept articulated by American Institute of Architects six years ago. (It is an approach that in many ways mimics the refinement of a cost estimate throughout the development of a project broad at first, detailed in the end.)

ASHRAE advances this notion by identifying eleven distinct "modeling cycles," which occur at specific points in the development of a building project (see Figure 1). Each modeling cycle is characterized by a specific purpose, applicability, and type of analysis. Project teams are not necessarily required to execute all eleven modeling cycles but as a collective, the modeling cycles clarify the definition of the building energy modeling exercises critical to each stage of a project's design/construction/occupancy. 


Figure 1: ASHRAE Standard 209-2018 Building Energy Simulation Modeling Cycles by Project Phase.
Figure courtesy of Daniel Overbey.



The document is scoped specifically for new construction and/or major renovation. The standard takes a bold step toward designating an "energy modeler" not just as a specific role on a project team, but one who is also certified as a Building Energy Modeling Professional (BEMP), a Building Energy Simulation Analyst (BESA), or an equivalent individual meeting qualifications established by the authority having jurisdiction.

ANSI/ASHRAE Standard 209 both clarifies and increases the rigor of building energy modeling on a project. Adoption of the standard will prompt project teams to capitalize on the unique opportunities offered by building energy modeling when utilized as a design decision-making tool. Over time, it should also close the gap between predicated and measured energy performance, driving teams toward greater high-performance outcomes.

Learn more about ANSI/ASHRAE Standard 209-2018 by visiting