I am simulating a large theater with multiple levels (vertically) and with an opening in the roof that makes about 30% of the roof area. The theater is served by multiple AHUs. I have divided the large space into subspaces (Zones) based on AHUs' serving areas, such that each Zone is served by an AHU. I created opening surfaces between the adjacent zones (can be horizontal and vertical based on the Zone location relative to adjacent ones). I want to model the interflow between the zones - given mechanical ventilation - that closely represents the real life scenario. I have experimented with both AirFlowNetwork model and the ZoneMixing and the results of the two are different. I read that AirFlowNetwork model is more complex and detailed, yet it does not work/provide accurate results for some scenarios (e.g., Air circulation and/or air temperature stratification within a thermal zone.). I could not decide which is representative, sufficient, and reliable to use for my case. Given my limited expertise with Energy+, I would like to ask if I should use AirFlowNetwork model or ZoneMixing will be sufficient for this application. Additionally, I would appreciate any feedback, ideas, or suggestion regarding my request.
Regards,
Mariam* UPDATE *
Based on @Jason DeGraw's answer, I would like to ask if my strategy to approach this is reasonable. If ZoneMixing is used, I will need to include ZoneMixing objects in both directions in order to insure mass balance, correct? For example, assuming that Zone 1 and Zone 2 only interact which each other, I should have the following because ZoneMixing statement only affects the energy balance of the “receiving” zone and does not produce any effect on the “source” zone (Source: https://bigladdersoftware.com/epx/docs/8-4/input-output-reference/group-airflow.html#zonemixing). Hence, complementary mixing statements of zones with air exchange should be included while having Delta Temperature set to 0 in order to for mixing to occur regardless of the relative zone temperatures.
ZoneMixing,
Zone2_To_Zone1 , !- Name
Zone1 , !- Zone Name
On 24/7 , !- Schedule Name
Flow/Zone , !- Design Flow Rate Calculation Method
10.00000 , !- Design Level
, !- Volume Flow Rate per Area {m3/s/m2}
, !- Volume Flow Rate Per Person {m3/s/person}
, !- Air Changes per Hour {ACH}
Zone2 , !- Source Zone Name
0.0; !- Delta Temperature
ZoneMixing,
Zone1_To_Zone2 , !- Name
Zone2 , !- Zone Name
On 24/7 , !- Schedule Name
Flow/Zone , !- Design Flow Rate Calculation Method
10.00000 , !- Design Level
, !- Volume Flow Rate per Area {m3/s/m2}
, !- Volume Flow Rate Per Person {m3/s/person}
, !- Air Changes per Hour {ACH}
Zone1 , !- Source Zone Name
0.0; !- Delta Temperature
Under the assumptions that (1) the HVAC system design insures thermal comfort, and (2) the paths of air exchange between zone are independent of the AHU's supply-return air paths, I am thinking of using the air velocity thermal comfort requirements (which is I think is a maximum of 2 m/s) knowing the cross-section area between the zones and air density to set the maximum air exchange rates between the zones (i.e., Design Level). Kindly let me know if this makes a good strategy.
