ANSI/ASHRAE/IES Standard 100-2018 Energy Efficiency in Existing Buildings is hereby adopted by reference with the exceptions noted in this chapter of the Washington Administrative Code (WAC) updated February 7, 2024, to include Tier 2 covered buildings pursuant to RCW 19.27A.250, updated July 2024 to include district energy systems decarbonization pursuant to RCW 19.27A.260. In the event of a conflict between the standard and rules in this chapter, the provisions of this chapter apply.

ANSI/ASHRAE/IES Standard 100-2018 Energy Efficiency in Existing Buildings is adopted by the Washington state department of commerce pursuant to RCW 19.27A.200, 19.27A.210, and 19.27A.220. This standard has been adopted by reference and modified to implement the requirements for covered buildings as directed by the Washington state legislature. The legislature delegated the responsibility of adoption and amendment of this standard to the Washington state department of commerce.

Complying with this rule requires the user to comply with ANSI/ASHRAE/IES Standard 100-2018 as amended by this rule. When this rule amends a section of Standard 100, the entire section is published in the rule. The user will need to have both documents in hand, but detailed comparison within any one section is not necessary. Simply apply the entire section as published in the rule. All other sections in Standard 100 apply.

The Washington state administrative requirements for this standard are included in Normative Annex Z for Tier 1 covered buildings, Normative Annex Y for Tier 2 covered buildings, and Normative Annex W for district energy system decarbonization plans. For building owners that must comply with this standard, reading Normative Annex Z, Normative Annex Y, or Normative Annex W first allows the owner to put the rest of the standard in context. Multiple compliance options are available and should be reviewed prior to beginning implementation of this standard.