Re: [EnergyPlus_Support] Re: Can HVAC system take air from earth tubes instead of ambient?

On Tue, Jul 5, 2011 at 1:53 PM, wasilqayyum <wasilqayyum@xxxxxxxxxxx> wrote:

Thanks for the detailed reply.

What I'm trying to achieve is that I want to know what energy can be saved by using earth tubes by pre-cooling.

For example, I've created a building and put an ideal loads air system (cooling set point at 22oC) and summed up all values of Zone Sys Sensible Cooling to determine the cooling demand.

Now with the earth tubes, I'm having issues since the earth tube outlet temperature is higher than the room temp so its "heating". What I want is to route the earth tube outlet air (since its a little cooler than ambient, but not cool enough for thermal comfort) into HVAC system. Thus, the energy required by HVAC system to maintain 22oC should be less.

Will the approach you mentioned help me achieve this? Please explain if you can.

Any help will be very much appreciated.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jason Kirkpatrick <jason.alan.kirkpatrick@...> wrote:
>
> I have found it easier to run two simulations.
> The first one simulates the earth-tube only and then outputs the hourly dry
> bulb and wet bulb temperatures to a .csv file
> The second simulation utilizes EMS routines to replace the dry bulb and wet
> bulb hourly temperatures in the weather file with those found in the .csv
> output file but only for the outdoor air intake node... See code below:
> (note this was done with v.5 so there may be some updating that you need to
> do for v6)
>
> EnergyManagementSystem:Sensor,
> Earth_Tube_DB_Sched, !Name
> EarthTubeDBSch, ! Output:Variable Index Key Name
> Schedule Value; ! Output:Variable or Output:Meter Name
>
> EnergyManagementSystem:Sensor,
> Earth_Tube_WB_Sched, !Name
> EarthTubeWBSch, ! Output:Variable Index Key Name
> Schedule Value; ! Output:Variable or Output:Meter Name
>
> EnergyManagementSystem:Actuator,
> ET_OADB_Override, ! Name
> DOAS Outside Air Inlet, ! Component Name
> Outdoor Air System Node, ! Component Type
> Drybulb Temperature; ! Control Variable
>
> EnergyManagementSystem:Actuator,
> ET_OAWB_Override, ! Name
> DOAS Outside Air Inlet, ! Component Name
> Outdoor Air System Node, ! Component Type
> Wetbulb Temperature; ! Control Variable
>
> EnergyManagementSystem:Program,
> SchedOA, ! Name
> SET ET_OADB_Override = Earth_Tube_DB_Sched,
> SET ET_OAWB_Override = Earth_Tube_WB_Sched;
>
> EnergyManagementSystem:ProgramCallingManager,
> Schedule OA, ! Name
> AfterPredictorBeforeHVACManagers, ! EnergyPlus Model Calling Point
> SchedOA; ! Program Name 1
>
> Output:EnergyManagementSystem,
> Verbose,
> Verbose,
> Verbose;
>
> Schedule:File,
> EarthTubeDBSch, !- Name
> Any Number, !- ScheduleType
> W:\M\CALC\ETDB.csv, !- Name of File
> 1, !- Column Number
> 0, !- Rows to Skip at Top
> 8760, !- Number of Hours of Data
> Comma; !- Column Separator
>
> Schedule:File,
> EarthTubeWBSch, !- Name
> Any Number, !- ScheduleType
> W:\M\CALC\ETWB.csv, !- Name of File
> 1, !- Column Number
> 0, !- Rows to Skip at Top
> 8760, !- Number of Hours of Data
> Comma; !- Column Separator
>
>
>
>
>
>
> On Sun, Jul 3, 2011 at 1:20 PM, YuanLu Li <yli006@...> wrote:
>
> > **
> >
> >
> > I think, you can feed the ET air to a small room (a separate zone) and
> > then exhaust or return it to the OA mixer, or a HVAC system..
> >
> > The HVAC system does not know whether the air is from the room or the OA
> > mixer.
> >
> > The OA mixer box is actually an air splitter, an air by-pass path, and an
> > air mixer. The releaf node air is fed to the inlet node via the
> > environment.
> >
> > If the inlet air volume low or zero, all the zone return air is directed
> > to the HVAC system.
> >
> > You need to decide which part of the building air is to be relieved with an
> > exhaust fan, so that the ET air is not relieved at the OA mixer.
> > =======================
> > There may be other ways. Think of an pratical real system installation and
> > then map it into the EPlus simulation system.
> >
> > The idea is similar to the domestic hot water system. The water from a
> > tank to the showers, etc. are thrown away and replaced by the main water
> > supply.
> >
> >
> >
> > Dr. Li
> >
> >
> > ------------------------------
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > From: wasilqayyum@...

> > Date: Sun, 3 Jul 2011 14:31:11 +0000
> > Subject: [EnergyPlus_Support] Can HVAC system take air from earth tubes
> > instead of ambient?
> >
> >
> >
> > Hello all,
> >
> > I'm simulation earth tubes for pre-cooling.
> >
> > However, the issue im having is that earth tubes output air directly into a
> > zone (building). But can I have it output air to a HVAC system instead? or
> > have an HVAC accept air from the earth tubes?
> >
> > Thanks.
> >
> >
> >
> >
>