ASHRAE’s new Standard 209-2018, Energy Simulation Aided Design for Buildings except Low Rise Residential Buildings, defines minimum requirements for providing energy design assistance using building energy simulation and analysis.

“For many buildings, energy modeling is typically employed only near the end of the design process to determine if a building meets minimum requirements for energy-efficient design, outlined in Standard 90.1,” said Jason Glazer, chair of the Standard 209 committee. “Standard 209-2018 requires building energy modeling earlier in the design process, so the information it provides will more effectively inform design decisions and result in higher performing buildings.”

This new standard will be useful to building owners, architects, government agencies and others who want their projects to benefit from the use of simulation. By referencing the standard, they can identify appropriate modeling tasks and procure modeling services that add value in the design process.

The standard also describes analysis activities from early concept development to post-occupancy. The standard applies to new buildings, major renovations and additions, and defines nominal requirements for using modeling to support integrated design efforts.

Standard 209-2018 defines general modeling requirements coupled with 11 modeling cycles, each with specific modeling goals that align with distinct phases of the design, construction or operation process. Each modeling cycle is an extension of the general modeling requirements, which represents a best practices approach for using modeling to inform design.

Seven design-phase modeling cycles, each with specific modeling goals coordinated with the typical design process. Each modeling cycle is an extension of a general modeling cycle that can be applied any time during design. Three additional modeling cycles are defined for construction and operation phases, and include a design and post-occupancy performance comparison.

The post-occupancy analysis is included to help both the owner and modeler understand how modeled results compare to actual energy performance to inform operation and assumptions used in future modeling projects. The minimum requirements of the standard can be met by completing a load-reducing modeling cycle early in the design process, as well as one additional design-phase modeling cycle. The full set of modeling cycles were developed to provide holistic modeling guidance and are included for completeness. While the standard can be applied with any design process, it is best utilized when included as part of an integrative design process.

The ASHRAE Standard 209-2018 is available for purchase.

ASHRAE, founded in 1894, is a global society advancing human well-being through sustainable technology for the built environment. The Society and its more than 56,000 members worldwide focus on building systems, energy efficiency, indoor air quality, refrigeration and sustainability. Through research, standards writing, publishing, certification and continuing education, ASHRAE shapes tomorrow’s built environment today.