I have a question relating to NC IEQ C 1. Outdoor Air Delivery Monitoring.
According to the “Intent” and “Requirements” of this credit, checking whether ventilation systems supply minimum outdoor airflow rate at all expected system operating conditions is the key function of an outdoor airflow measurement device, not measuring the outdoor airflow rate at all expected system operating conditions.
However, the ‘LEED Reference Guide for Green Building Design and Construction, 2009 Edition’ says, “The direct outdoor airflow measurement device must be capable of measuring the outdoor airflow rate at all expected system operating conditions, within an accuracy of plus or minus 15% of the design minimum outdoor air rate.” (page 439, line 2 to 5)
Is it means that outdoor airflow measurement device should have a capability of measuring the airflow rate of which amount is equal to the amount of maximum supply airflow rate if a VAV system have 100% outdoor air operating mode?
Andrew Mitchell, P.E.
PrincipalMitchell Gulledge Engineering, Inc.
LEEDuser Expert
126 thumbs up
March 17, 2014 - 8:52 am
You need to determine the OA flow rate that you need to satisfy your system in every condition. It is up to you whether you decide to use the most critical flow as a constant volume flow or to use a setback strategy to determine a variable setpoint. Regardless of which one you choose, your flow station should measure the air and sound an alarm if it is outside of the acceptable variance from the flow setpoint.