[EnergyPlus_Support] Room conditioned with relief air?

["raftery.paul" <praftery@xxxxxx>]

Has anyone had problems with modelling zones that are conditioned by
relief air? Is this a problem that is in the developers 'to-do' list?

Basically, I have a building with 2 CAV systems with air economisers
in which the fan room is conditioned with relief air from both AHUs.
Does anyone know of a simple way to connect this zone so that it is
conditioned in this way? Is there a way that you can connect both
relief air nodes (or even just one) to the zone?

Currently the workarounds that I'm thinking of are:

1) Put the zone in the return air stream as a return air plenum.
However, this would mean that the return air that eventually gets to
the economiser would be significantly cooler/warmer depending on heat
transfer between the zone and the outside.
2) Create a separate purchased air system that supplies air to the fan
room with maximum heating and cooling flow rates that are the same as
the total combined flow from the AHUs. The problem with this is that
the heating and cooling supply air temperatures are fixed, and cannot
be varied with a schedule. Thus, I will have to use a supply air
temperature that is the average of the return air temperature to the AHUs.

Hopefully someone has a better idea as neither of these are ideal!
-- 
Regards,
Paul


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