855773520-LEED-v5-ID-C-Reference-Guide-Launch-Edition-1 - Page 116

Extracted Content

Summary of ASHRAE 90.1, Section 4.2.1 compliance paths Projects must choose from one of the following compliance paths from ASHRAE 90.1, Section 4.2.1.3. Alterations of Existing Buildings:

• Prescriptive method

o ASHRAE 90.1-2019, Sections 5–10 (for projects applying Option 1)

o ASHRAE 90.1-2022, Sections 5–11 (for projects applying Option 2)

• Energy cost budget method (ECB)

• Appendix G performance rating method (PRM)

The path commonly referred to as the prescriptive method requires individual compliance with each referenced 90.1 section for the elements within the project scope (building envelope, HVAC, SWH, electrical power, lighting, other equipment, and in 90.1-2022, additional efficiency requirements). It is the most appropriate path for projects with limited scope.

The ECB method and Appendix G PRM offer greater flexibility to trade-off performance between different systems. These methods rely on energy modeling to demonstrate that the proposed project performs at least as well as a project meeting the prescriptive requirements.

Project teams must apply either the prescriptive method or the Appendix G PRM to pursue additional credit for regulated energy efficiency in EAc2: Enhanced Energy Efficiency .

Initial build-out, substantial alterations, and other alterations ASHRAE 90.1-2022 requires initial build-out projects and substantial alterations to meet a higher bar for energy efficiency than other interiors projects. Similar increased efficiency criteria apply to initial buildouts and substantial alterations documented using ASHRAE 90.1-2019, Appendix G.

• Initial buildout . This refers to work to finish a space within a building for initial occupancy.

• Substantial alterations . This refers to major replacement of systems or components in existing buildings for two out of three major building systems (HVAC, lighting, or building envelope). Refer to ASHRAE 90.1-2022, Section 11.1.4.1 Substantial Alterations to Existing Buildings for a full definition.

• Other alterations . This refers to interior fit-outs of existing buildings that are not substantial alterations.

ASHRAE 90.1-2022, Section 11 Additional Efficiency Requirements apply to initial buildouts and substantial alterations, but not to other alterations. These additional savings are also accounted for in determination of ASHRAE 90.1-2022, ECB method requirements.

U.S. Green Building Council LEED v5 Reference Guide for Interior Design and Construction, April 2025 Launch Edition 105