include macroflow link in dynamic simulation

[aas333]

I am trying to include a macroflow link in my dynamic simulation. Whenever i tick the box to include the macroflow link the simulation will stall in the first time step.

Is there anything I need to do to incorporate the link into my dynamic simulation, such as in suncast when you must run shading calculations prior to dynamic simulation? I do not see anything of this nature in the ribbon on the VE program, or in the macroflow users guide.

Any help is appreciated.

[PCully]

Hi,

Every project will have default opening types defined but you should go into MacroFlo to check the opening type definition and assignment is appropriate for your model. YOU check the leakage, openable areas, equivalent orifice areas and controls that are specified here.

When you say this stalls I guess you are getting an instability which can happen if the openable areas are large and the controls are drastic i.e. instantaneous open/close rather than something with a damper

Or if it's a simulation error of some form then perhaps the opening types/input file for the sim hasn't been generated properly. You don't run a calculation as with SunCast but MacroFlo creates its own files that are stored in the project MacroFlo folder and are then read in by Apache in the same way SunCast does.

One last point is the bulk airflows calculated through external openings and through internal openings and holes by MacroFlo will interact with the air volumes specified flowing round an ApacheHVAC network so if you are using both in conjunction the strategies needs to be aware of each other.

Hopeful this gives you a bit more info to troubleshoot here

Phil

[aas333]

Thanks for your response Phil,

I have taken a look at the openings and everything seems to be in order, I tried running a simulation with just Macroflow this morning, and the simulation ran. When I run the simulation it appears to save the file as a .asp as is typical of the other results files. Are you saying I must run a macroflow only simulation, specify to save the file in the macroflow folder, then re-run the simulation with the macroflow link included?

[PCully]

no you don't need to do that. When you into the MacroFlo interface it should create the project .mfo and .mfl files int he MacroFlo folder of the project, Apache just needs access to these to allow the MacroFlo sim to run.

The simulation itself should just be run as normal except you tick on the MacroFlo link on simulation settings.

There have been issues with this in the past due to file paths and not being able to reference the files. If you are running on a server or have a long project name or file path (or it has unusual characters or dots in it) then this may be related and a save as should resolve.
Also avoid one character project names as there was a problem with an older version of VE that it couldn't simulate

Phil

[aas333]

I think the error was I wasn't giving the simulation enough time to run. I started a simulation and left the office for about an hour, came back and only 8 ten minute time steps had occurred. Is it typical for the simulation to take noticeably longer while having macroflow ticked than with out? I can usually run a year simulation with suncast and apacheHVAC links in under an hour.

[PCully]

I'm afraid my answer to this question is going to be a bit wooly!

Depends on the complexity of the model. The more openings we have (windows, doors, holes) both external and internal then the more calculations need to be run to track the bulk airflows, also as it will be calculated in conjunction with ApacheHVAC then the network status needs to be pre-calculated before the simulation starts and then at every timestep to calculate the pressure differences and bulk airflows.

It would certainly add to the simulation time and results filesize but I'm not so good at benchmarking what is expected

Phil