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
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
March 25, 2019 - 3:23 pm
I would question the reviewer with a project team inquiry. The adjustment should be applied to the baseline airflow through the device, not the proposed airflow. It should be based on the baseline outdoor airflow. You can only take the pressure drop adjustment for heat recovery devices that are required to be installed in the baseline according to Section G3.1.2.11. The pressure drop should be identical to the proposed pressure drop if such a system is required in the baseline.
Dat Nguyen
Thermal Engineer, Energy Modeller1 thumbs up
April 12, 2021 - 3:24 am
Dear Mr. Marcus,
My problem same as above, I auto-sized the system 08 baseline (IES-ve software) with OA flow rates intake this system then the supply fan power of this system higher than the "Allowed fan power" in the Minimum Energy Performance file. I have some questions that need your answer.
1. The fan supply power has calculated include the pressure adjustment of the OA flow rate throughout the filter device. Is it correct?
2. If the question above "correct". I must enter the value OA flow rate in pressure adjustment below the form with the air filter device same as the Proposed air filter?
Best regards.
Tyler Thumma
7GroupLEEDuser Expert
60 thumbs up
April 21, 2021 - 11:31 am
1. Yes, assuming the filter in the design is installed for the OA only. If it is installed for the total supply airflow, then the Baseline supply airflow should be used to calculate the pressure drop adjustment.
2. In the Minimum Energy Performance Calculator, you would enter the applicable Baseline airflow in the correct row for the filter rating in the design.