ASHRAE STD 62.1
Ventilation for Acceptable Indoor Air Quality
|Publication Date:||26 June 2019|
The Natural Ventilation Procedure was recently modified to require mechanical ventilation with certain exceptions. Addendum l provides specific requirements for the exceptions by providing a clear compliance path. It also recognizes that there are inherent health issues with outdoor air in many locations in the world and updates the prescriptive requirements based on recent studies and airflow evaluations.
Outdoor air requirements specified in Section 6.2.1 have been applied to naturally ventilated buildings, essentially prohibiting purely naturally ventilated buildings in cities that don't meet national outdoor air standards. Although this is not the best solution, it prioritizes occupant health and follows national guidelines already applied to other Standard 62.1 procedures until a new methodology is developed.
The prescriptive path has been improved by removing the openable area requirement of 4% of net occupiable floor area and introducing two prescriptive paths for sizing the required openable area that better respond to program in the zone and window type.
A four-point definition of a naturally ventilated engineered system has been developed to require designers to more fully document natural ventilation systems that do not meet prescriptive values.
An informative appendix that augments the engineered system definition has also been developed and will be presented as a separate addendum.
Note: In this addendum, changes to the current standard are indicated in the text by underlining (for additions) and (for deletions) unless the instructions specifically mention some other means of indicating the changes.