Dear all,
I am trying to model a VRF system as Packaged Variable Volume Variable
Temperature system.
My building has four external VRF units connected to terminal units for each
space in the interior. According to the power point presentation on the
subject, it should be modelled as PVVT with separate system for each zone.
In this case what values would you use? Would it be the same as my original
model or is there a way to define values with different proportions based on
the initial ones?
Wouldn?t it make more sense to design 4 PVVT as many as the VRF I have? And
in this case which is the zone controlling the system? If I ?m not wrong,
eQUEST only allows to choose one.
And one more general question: eQUEST creates by default plenum for each
space and HVAC systems with all zones. Would you remove these default HVAC
systems together with the unconditioned spaces and plenums?
Thank you very much.
Best regards,
Eleni
Eleni,
As far as input values, I would guess that you could add existing data for the spaces, such as flow rate and temperature setpoints. You could also let it autosize the units. I'm not really sure what would be best.
Good Luck,
Matt Clough
Matt,
Thank you very much for your answer. So, when modelling one PVVT for each
room, the external VRF units don?t appear in the model at all if I
understand correctly? My concern is that LEED will expect to see in the
model the four units that we actually have in the building.
I see what you mean with the numbering system, but this only helps us,
without actually being taken into consideration somehow in the model,
doesn?t it? Thanks again.
Eleni Soulti
I'm not really sure what the LEED reviewers are expecting to see. I haven't tried this technique for a LEED submission, so maybe other members could shed some light on this issue.
But, yes. The condenser units don't explicitly show up in the model. If you want to see the condenser units explicitly shown, use the WSHP/PVVT approach, which shows the condenser units as the heat rejection component, and the fan coils as the PVVT component. I believe this will give you more conservative energy usages because equest only allows for a single speed compressor.
Regards,
Matt Clough