ASHRAE - 55 ADD A
Thermal Environmental Conditions for Human Occupancy
|Publication Date:||30 April 2021|
Addendum a adds a new method for the assessment of local thermal discomfort with vertical air temperature gradient between the head level and ankle level. Recent studies found that the current limits of 3°C (5.4°F) for sitting and 4°C (7.2°F) for standing occupants between head and feet are unnecessarily strict. These limits may impede the application of thermally stratified systems that are believed to be more energy efficient and associated with better ventilation effectiveness. The new method applies to occupants with clothing insulation less than 0.7 clo and metabolic rate less than 1.3 met, complying with the entire Section 5.3.3, "Local Thermal Discomfort." The addendum was added using mandatory language in the body of the standard. Informative Appendix I has been updated to take into account the new method. The new method is based on the work described in Liu et al. (2020).
Note: In this addendum, changes to the current standard are indicated in the text by underlining (for additions) and
strikethrough (for deletions) unless the instructions specifically mention some other means of indicating the changes.