[Trace-users] Split System with DOAS for LEED

[Bob Fassbender]

Robert-

Sorry, but no, it is not acceptable to model as 1 system since your model
will not match your design documents, and your LEED reviewer will probably
have a system overload and die. You do not want that blood on your hands.

They are both very common points of confusion in TRACE (as John confirms!)
so I answered your questions at:
http://energy-models.com/forum/energy-modeling-software/trace-700/dedicated-oa-and-split-system#comment-1261


I posted an image too, and the post is pretty long, so I left it on the
forum.

I briefly addressed John's return air volume problem as well. Don't forget
to click the image to enlarge it!,

Bob

On Thu, Feb 3, 2011 at 3:46 AM, Robert Arnott <arnott.robert at gmail.com>wrote:

> 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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