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Performers:

  • Pacific Northwest National Laboratory – Richland, WA

Performance Period: Oct. 1, 2019 – Sep. 30, 2022

Funding Type: FY19 Lab Call

Budget: $600,000

Related Projects: ASHRAE Standard 229P Development

Project Overview

ASHRAE Standard 90.1 specifies minimal energy efficiency requirements for commercial buildings.  There are two paths for demonstrating compliance with this standard and others like it.  The prescriptive path is essentially a checklist that attests that the proposed building complies with every individual requirement; it is simple to implement but does not provide design flexibility.  The performance path uses building energy modeling (BEM) to show that the proposed building meets or exceeds the performance it would have had had it met each of the prescriptive requirements; it is more complicated but provides greater design flexibility.  Performance path compliance is what enables buildings to have nearly 100% glazing ratios despite a prescriptive limit of 40%.  For those buildings, designers use performance path compliance to demonstrate that they have compensated for the increased glazing ratio with greater efficiencies elsewhere.  In ASHRAE Standard 90.1, the performance path modeling procedure is specified in "Appendix G: Performance Rating Method (PRM)" and it is used not only in code-compliance but also in beyond-code applications like LEED.

Increasingly, software vendors are automating the Appendix G procedure for generating a "prescriptive baseline" model from a model of the proposed building.  However, the creation of the proposed building model is obviously more difficult to auotmate, and the Appendix G requirements for creating this model are intense as well.  This puts performance-path code compliance and beyond code applications like LEED and whole-building energy efficiency incentives beyond the reach of most small commercial building projects with small design (and modeling) budgets.

This project is attempting to close this gap by creating a simplified version of Appendix G with reduced modeling requirements that is targeted at smaller and simpler commercial buildings.  The bulk of the project involves using simulation to determine which simplifications are acceptable under which conditions and to create an a priori characterization of these conditions.

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