ASHRAE - GUIDELINE 36 ADD C
High-Performance Sequences of Operation for HVAC Systems
Organization: | ASHRAE |
Publication Date: | 1 August 2023 |
Status: | active |
Page Count: | 6 |
scope:
FOREWORD
Addendum c fixes an error in the minimum outdoor airflow set point logic for ASHRAE Standard 62.1 ventilation. There may be instances where the zone primary airflow rate (Vpz) is lower than the required zone outdoor airflow (Voz), causing the zone primary outdoor air fraction (Zpz) to exceed 1 and the minimum outdoor airflow set point to be driven to the design total outdoor air rate (DesVot).
A high limit of 1 has been added for the calculation of Zpz to prevent this. A limit of Zpz on transition to Occupied Mode has been added to prevent the minimum outdoor airflow set point from immediately jumping from 0 cfm to DesVot at the start of occupancy. A five-minute rolling-average has also been added to the Zpz calculation to counteract instabilities in the Vpz reading.
This addendum also moves the Zpz calculation from the Multiple Zone VAV Air Handling Unit section to the Generic Ventilation Zones section, as the Zpz calculation should occur for all ventilation zones, not at the air-handling unit.
Note: In this addendum, changes to the current guideline 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.
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