[Bldg-sim] PSZ Very High Unmet Hours

[Adam Gonthier]

Dear eQuest users, 

 

I am having some difficulty with a project I am working on, and I was
hoping I could receive some help or any information on a building a with
packaged single zone units with DX cooling and hot water coils for
heating, with a VFD to vary the supply flow (there are no VAV boxes in
the system, and the supply reacts to overall building pressure rather
than specific zonal needs determined by pressure sensors in the
ductwork).   There is no reheat in the system either.  

 

It is a LEED for schools project where the simulation of the proposed
model shows very high unmet loads for heating and the total energy
consumption for space heating is 199 MBTU which is unrealistically low
as compared to the baseline model space heating which is 6369 MBTU.  We
do not see many unmet hours in the control zone, but since the unit
supplies many zones, we are getting very high unmet heating hours in
non-control zone spaces.  We are seeing on the order of 4000-5000 hours
unmet in many zones.

 

I have modeled the heating for all zones by specifying the 

Heat Source as hot water loop, 

The Zone Heat Source is not installed, as the design has no reheat. 

Zone entering maximum supply temperature is at 110 degrees. 

Hot deck max leaving temp is 80 degrees

Reheat delta T: n/a

 

Many thanks in advance, 

Adam A. Gonthier

Energy Engineer
Horizon Engineering Associates, LLP
347.297.9005

www.horizon-engineering.com <http://www.horizon-engineering.com/> 

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