New ASHRAE Standard Addresses Energy Modeling

Originally published by: Retrofit MagazineMay 1, 2018

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ASHRAE has published a standard describing a methodology to apply building energy modeling throughout the design process.

ASHRAE 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.

The standard defines consistent energy modeling procedures to quantify the impact of design decisions when they are being made. To minimally comply with Standard 209-2018, building project teams must evaluate energy-efficiency options using modeling early in the design process (schematic design).

“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,” says 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 inform design decisions and result in higher performing buildings.”

This 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 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 to help owners and modelers understand the impact of design phase modeling assumptions and inform future modeling efforts.