“ASHRAE recognizes that building energy simulation is most useful when it can inform the design process to reduce energy use,” said Jason Glazer, chair of the Standard 209P committee. “The standard was created to advance the use of timely building energy modeling to quantify how design decisions can affect building energy use when those design decisions are being made.”

While earlier draft versions of the proposed standard incorporated energy modeling into the typical design process divisions of schematic design, design development, etc., the committee realized that many tasks, data, and goals of each modeling effort, or cycle, were similar enough to create a “generic modeling cycle.” The draft standard was rewritten to incorporate a generic modeling cycle that is augmented with additional directions to create several specific modeling cycles that are incorporated into the typical design process.

Standard 209P defines seven design phase modeling cycles with specific modeling goals that are defined and coordinated with the typical design process, and three modeling cycles are defined that apply during construction and operation of the buildings. Each modeling cycle is an extension of a general modeling cycle that can be applied any time during the design process that energy modeling is needed to inform design decisions. In addition, a post-occupancy comparison is included to help owners and modelers understand how modeled results compare to actual energy performance and inform assumptions in future modeling projects.

“The minimum requirements of the standard can be met by utilizing building energy modeling to evaluate load reduction measures early in the design process, as well as one additional design phase modeling cycle,” Glazer said. “Other modeling cycles are included for organizations that wish to adopt more robust energy modeling requirements.”

While the standard can be applied with any design process, it is anticipated to be most effective when included in an integrative design process. It is expected that 209P will be adopted by organizations that certify high performance buildings as well as utilities and agencies that provide incentives for low energy buildings, and used by building owners and architects seeking a uniform way to specify a scope of work for building energy modeling.

To comment or learn more, visit www.ashrae.org/publicreviews.

Publication date: 5/3/2016

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