Hi all,
I’ m simulating a 100% outdoor air loop. The air loop provides
fresh air and heating or cooling to 3 rooms with the same occupancy, electric
equipment and lighting profile.
People is allowed to smoke inside the building so the outside air
flow rates are huge ( 5 ach).
The building will not be always 100% occupied. To reduce energy consumption
in partial occupancy scenario, the air handling unit will have 4 levels of air
supply.
To approach this on energyplus, I’ve created a VAV air loop with
terminal unit VAV: HeatandCool: NoReheat. The lower occupancy fraction predicted
is 0.50, so I’ve set the zone miminum air flow fraction of 0.50.
The leaving coil air temperatures modulated between 19 and 25
ºC with Set-point managers single zone heating and cooling placed in one of the
rooms.
On the Controller: OutdoorAir I’ve set:
Controller:OutdoorAir,
AHU5-6 OA Controller, !- Name
AHU 5-6 Relief Air Outlet, !- Relief Air Outlet Node Name
AHU 5-6 Air Loop Inlet, !- Return Air Node Name
AHU 5-6 Mixed Air Outlet,!- Mixed Air Node Name
AHU 5-6 Outside Air Inlet, !- Actuator Node Name
16.250, !- Minimum Outdoor Air Flow Rate
{m3/s}
16.250, !- Maximum Outdoor Air Flow Rate
{m3/s}
NoEconomizer, !- Economizer Control Type
ModulateFlow, !- Economizer Control Action Type
, !- Economizer Maximum Limit
Dry-Bulb Temperature {C}
, !- Economizer Maximum Limit
Enthalpy {J/kg}
, !- Economizer Maximum Limit
Dewpoint Temperature {C}
, !- Electronic Enthalpy Limit Curve
Name
19, !- Economizer Minimum Limit
Dry-Bulb Temperature {C}
NoLockout, !- Lockout Type
FixedMinimum, !- Minimum Limit Type
OccupProfile, !- Minimum Outdoor Air Schedule
Name
on, !- Minimum Fraction of Outdoor Air
Schedule Name
on; !- Maximum Fraction of Outdoor Air
Schedule Name
The OccupProfile schedule was defined with the 4 fan operating
levels based on the predicted occupancy profile.
Because I’ve defined FixedMinimum limit on the outdoor air
controller, in partial occupancy scenario I was expecting the unit to supply at
least the minimum air flow rate defined by the Minimum Outdoor Air Schedule
Name.
In the winter, the calculated supply air temperature is 19 ºC
( the lower temperature defined on the set-point manager) but the supply air
flow rate is lower than the defined by the !- Minimum Outdoor Air Schedule Name.
I’ve read input output reference on this topic, and for my
understanding, VAV flowrate should be restricted to the minimum outdoor air
defined.
My question is:
In the simulation, VAV only considers the minimum air flow rate
defined in the VAV: HeatandCool: NoReheat or It is meant to consider also the
outside air controller action?
Thanks in advance for your help,
Best regards
Filipe Madureira
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