Natural ventilation across holes not simulating

aslanswish · Posts: 3

i have a building with holes representing large glass slider for nat vent purposes. i have checked the correct boxes etc but when i run the cfd boundary conditions after the simulation the results do not show any airflow across the holes.

most of the building is mechanical but the natural vent is selected for block 1 zone 3 and block 3 zone 1.

am i doing something wrong?

Tx

Andy Tindale · Posts: 2617 Location: Stroud

Have you first run an EnergyPlus simulation to calculate the flows through the opening, then imported the simulation results?

There is a webinar on how to do this at:

http://www.designbuilder.co.uk/content/view/107/185/

Click on the "DesignBuilder EnergyPlus CFD" link

Andy

aslanswish · Posts: 3

definately. i ran the simulation. checked the air in and air out in the graphical display and that looks ok, but i cannot tell from the graphic if it is through window or hole.
when i import to cfd boudary conditions there is air in and air out but it is only through the windows. the holes show 0 airflow.

i have checked marked natural ventilation for these zones. nat vent is on calculated in options tab.
in output i have marked the options indicated in help and videos.

still no airflow across holes.

aslanswish · Posts: 3

i ran a simple box cfd nat vent calc in the beta version and ran into the same issue. holes did not show air in or out.

i unistalled and put version 2 back on my computer and ran the same box scenerio. the cfd boundary conditions showed air in and out of holes like they are supposed to.

conclusion. beta version is not modeling exterior holes properly.

can you confirm?

tx

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i would like to add for disgnbuilder code writers. i reloaded the beta version 3.0007 and the holes modeled as expected.

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