I’m modeling an old house with no mechanical ventilation, but I can’t get the term to go away in the load balance. I’ve set vent_per_floor, vent_per_person, and vent_ach to 0.
That will get rid of the outdoor air required to maintain ventilation requirements, but it won’t get rid of the outdoor air that is conditioned to heat and cool the house. “Mechanical ventilation” refers to both types of outdoor air, since the zone supply airflow rate and temperature satisfies both ventilation and heating/cooling requirements.
If your house isn’t using an air-based heating/cooling system, you can specify an alternate (non-air-based) system from HB’s HVAC templates, or by creating your own using HB/Ironbug’s HVAC tools. That will get rid of the mechanical ventilation component.
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This is technically correct but I think a simpler way to explain this is that, when you set the ventilation requirements to zero as @mikeheiss did, all of the outdoor ventilation air is essentially coming from the use of the airside economizer that is built into the default Ideal Air System. So all of that ventilation term is “free cooling” from outdoor air that would otherwise be an active cooling load. If you’re trying to represent a system that cannot do air side economizing, you can edit the default Ideal Air system properties using the HB IdealAir component. Just set the _economizer_ to No Economizer.
@chris has the right answer here, you should ignore mine. It’s wrong for me to say there’s a dual conditioning/ventilation role for your mechanical ventilation given that there’s zero outdoor air to condition in your case, (even though the airside economizer brings in air that cools your zone, it’s not conditioned by your system).
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