I'm trying to calculate the energy impacts of the damper leakage limitations in ASHRAE 90.1. To do this I'm trying to better understand the pressure differential across exhaust and intake dampers using EnergyPlus.
I'm reporting the following variables
- Outdoor Air Stream Node Air Pressure
- Relief Air Stream Node Air Pressure
- Mixed Air Node Air Pressure
- Outdoor Air Pressure
- Return Air Stream Node
as expected (1) and (4) are pretty much identical (+/- 1%, which i assume is due to interpolation). (5) is equal to (2) and they are both a constant 99716.667 Pa at every timestep all year and (3) varies when the system is on as one would expect.
so, my questions are as follows:
Why are (5) and (2) constant and where does that value come from?
If the system's outdoor air and exhaust dampers were closed but the system was running what pressure differential between these nodes shoudl be used to estimate air leakage?
Thanks.