[Trace-users] Split System with DOAS for LEED

[Robert Arnott]

Hi all,

I am a new Trace 700 user and I'm busy modelling a building for LEED. I'm
struggling with two fundamental aspects of how the HVAC system modelling
works in Trace.

1. The building uses a split unit heating/cooling system, with a completely
separate dedicated outdoor air system for fresh air. The fresh air supply is
constant and does not vary with the heating and cooling load. The split unit
draws air directly from each zone (recirculating indoor air only) and is not
at all connected to the supply ducting of the fresh air. Since there are two
completely independent systems serving the same zones, how should this be
modelled for LEED? Would it be acceptable to assume that a single system is
being used, and that the heating/cooling is done directly on the supply air?

2. All zones receive fresh air, with only the bathrooms exhausting air,
creating a definite airflow network between the zones. If I set every zone's
"Adjacent air transfer from room" to the passageway connecting all the
zones, will Trace determine the correct airflow rate and direction between
each zone? Or is the adjacent air transfer directional, so that the bathroom
would need to be set to have an airflow transfer from the passage, then the
passage would need an airflow transfer from multiple zones (but trace only
allows a single zone to be set)?

I'd appreciate any feedback. Thanks in advance!

Regards,
Robert
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