ASHRAE Standard 100 users' guide

About Standard 100

ANSI/ASHRAE/IES Standard 100-2018: Energy Efficiency in Existing Buildings (Standard 100) is an international building standard developed by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE).

Standard 100 is an ANSI-approved standard that was co-sponsored by IES. (ANSI refers to the American National Standards Institute, while IES refers to the Illuminating Engineering Society.) Standard 100 applies to existing buildings and provides procedures and program essentials through improved energy efficiency and performance in existing buildings.

Standard 100 is not required by the BC Building Code but using it can help owners and managers of existing buildings.

About the users' guide

The purpose of this users' guide is to provide additional explanation, examples, and reference material to supplement Standard 100. It offers useful material for the primary parties named in the standard, including but not limited to policy makers and program implementers who use the standard. The guide should be used in conjunction with Standard 100.

Each chapter of the guide is divided into topics relevant for specific roles, including:

  • Authority having jurisdiction
  • Building owner
  • Building manager
  • Building operator
  • Energy manager
  • Qualified energy auditor
  • Qualified person determining compliance 

The guide is generally applicable anywhere Standard 100 is implemented, although it provides some supplemental material specific to the regions of British Columbia and Washington State.

Download a copy

Use in Washington State

This users' guide may not fully capture or reflect Washington State amendments to Standard 100, as required by law. See Washington State’s Clean Buildings website for further details. 

How the users' guide was developed

RDH Building Science is the principal author and editor of this users' guide. It was developed with support from BC Hydro, the Province of British Columbia, and the Northwest Energy Efficiency Alliance, and in partnership with the University of British Columbia and the State of Washington Department of Commerce.

Page last updated: May 31, 2021.