Dear everyone,

For one of our project we received the Review Comment regarding to pressure drop adjustment calculations.

It states that :

"pressure credits may only be taken in the Baseline Case for the design airflow associated with these systems. For example, if the Proposed Case has F7 filtration for the air handling units supply airflow (5,660 l/s), then this pressure credit may only be taken for 5,660 l/s of the Baseline Case airflow. Update the calculator and the model to reflect revised fan powers."

Previously we modelled pressure drops based on Baseline Supply Airflow.

For that case I understand that pressure adjustment should be modelled with design OA airflow. In other LEEDuser posts I read that airflow used to calculate pressure drop should be based on airflow through each particular device. In LEED 2009 it was not a problem because Baseline and Proposed OA were the same, but here they are different now.

My question is if airflow used for pressure drop calculation of fresh air filter should be calculated based on Baseline OA which is lower or Design OA associated with spaces served by system.

Calculation based on Proposed OA are quite tought. 

Also I am not sure if pressure drop for heat exchanger device is calculated based on design efficiency or 50% of Baseline efficiency so for every system it is the same.

Best Regards