Referenced in the 2018 IECC. Standard 55 specifies conditions for acceptable thermal environments and is intended for use in design, operation, and commissioning of buildings and other occupied spaces. The 2013 edition of ANSI/ASHRAE Standard 55 incorporates 18 published addenda to the 2010 edition, and provides two compliance methods: a graphic method for simple situations and an analytical method for more general cases. Analytical calculations can be easily performed using the ASHRAE Thermal Comfort Tool software available from the ASHRAE Bookstore.
Since 2010, Standard 55 has been rewritten with a renewed focus on application of the standard by practitioners and use of clear, enforceable language. Requirements are now clearly stated and calculation procedures appear sequentially. For example, during design, a "representative occupant" must be defined, and the air speed and temperature they experience must be an average across the human body at three typical measurement heights. All informative background information has been moved to informative appendices.
Other noteworthy additions to the standard include an allowance for the cooling effect of air movement as a way to extend the upper limit of the comfort zone in naturally conditioned spaces, the addition of a predictive model for occupant clothing behavior based on extensive field research, and major revisions to Section 7 procedures for measuring comfort in existing spaces.
Documentation requirements to show that a design complies with Standard 55 are contained in Section 6, and a sample compliance form is provided in Appendix J. Both of these sections are clarified and streamlined for use by owners and third-party rating systems.