The 100% OA is usually only a small fraction of the building volume. Why bother to calculate the heat balance using the OA property.
Unless you are modelling Tarzan's tree house (no walls) or a very small hut (small air volume)..
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: robin.genoud@xxxxxxxxx
Date: Thu, 5 May 2011 08:15:53 +0000
Subject: [EnergyPlus_Support] Re: ZoneVentilation Volume Standard Density vary
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: robin.genoud@xxxxxxxxx
Date: Thu, 5 May 2011 08:15:53 +0000
Subject: [EnergyPlus_Support] Re: ZoneVentilation Volume Standard Density vary
Lixing,
I think my last problrm comes from the Actuator Node of the OutdoorAir Mixer of my loop. In fact, I have an Outdoor Air Node for Actuator Node (called Outdoor Air Inlet Node). When I look at the features of this node (current density, temperature, pressure) they are the same as the oudoor air, which is what I want. But when I look at this Node MassFlowRate, I have a constant value and the flow seams to be calculated with a constant density of 1.1704 kg/m3. I don't understand why EE+ doesn't take the current outdoor air density to calcul the MassFlow. I have uploaded my file, called venti_ailloop_1zone.idf
Thanks in advance.
Robin
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "rgen1202" <robin.genoud@...> wrote:
>
> Lixing,
>
> I am aware of this density calculation. But I am still surprized of the way EnergyPlus model the ventilation(and the infiltration too) because if I model the mechanical ventilation with an Air Loop containing one exhaust fan constant volume and a 100% OA mixer, I get a constant Mechanical Ventilation Volume Standard Density. Therefore, the MassFlowRate in this case isn't calculated with the outdoor air density but with the standard density and I don't understant why.
>
> In fact, I am interested in the building energy consumption, and I don't know which model is the more accurate, since I have a significative difference in the cooling load due to outdoor air.
>
> Robin
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@> wrote:
> >
> > Robin:
> >
> > This is caused by air density calculations using different pressures,
> > temperature, and humidity ratio.
> >
> > In the calculation subroutine, the mass flow rate is required in the
> > calculations and is equal to the volumetric flow rate from your input times
> > air density as a function of outdoor conditions (T, P, and W). In the report
> > subroutine, the volumetric flow is calculated using the mass flow rate
> > divided by the air density as a function of standard condition. The
> > different densities are used in calculation and reporting. That is why you
> > see minor differences shown in outputs.
> >
> > Hope this helps.
> >
> > Lixing
> >
> > -----Original Message-----
> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of rgen1202
> > Sent: Wednesday, May 04, 2011 3:17 PM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > Subject: [EnergyPlus_Support] Re: ZoneVentilation Volume Standard Density
> > vary
> >
> > Lixing,
> >
> > Thanks for your answer. I uploaded the file in Files>Problem_Submittals
> > http://tech.groups.yahoo.com/group/EnergyPlus_Support/files/_Problem_Submitt
> > als/.
> > Its called ventilation_mech.idf . Its a single zone building with only
> > ZoneVentilationDesign Flow Rate. I used the FRA_LYON_IWEC.epw for the
> > weather (I uploaded it too).
> >
> > Thanks in advance.
> >
> > Regards.
> >
> > Robin
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@> wrote:
> > >
> > > Robin:
> > >
> > > If you report Zone Ventilation Volume Standard Density, it should give you
> > a
> > > constant value. Please upload the input file and tell us the weather file
> > > name if this weather file is downloaded from the energyplus web site. We
> > > will take a look.
> > >
> > > Lixing
> > >
> > > -----Original Message-----
> > > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Lixing Gu
> > > Sent: Wednesday, May 04, 2011 1:29 PM
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > Subject: RE: [EnergyPlus_Support] ZoneVentilation Volume Standard Density
> > > vary
> > >
> > > Robin:
> > >
> > > I think you may use one of two output variables to report volume flow
> > rates:
> > >
> > > HVAC,Sum,Zone Ventilation Volume Flow Rate Current Density [m3/s]
> > > HVAC,Sum,Zone Ventilation Volume Flow Rate Standard Density [m3/s]
> > >
> > > It was found as a bug to report volume flow rates and was fixed for the
> > next
> > > release. It is a report error and has no impact of simulation results.
> > >
> > > Lixing
> > >
> > > -----Original Message-----
> > > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of rgen1202
> > > Sent: Wednesday, May 04, 2011 11:56 AM
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > Subject: [EnergyPlus_Support] ZoneVentilation Volume Standard Density vary
> > >
> > > Hello,
> > >
> > > I have a question about the ZoneVentilation DesignFlowRate.When I set the
> > > Design Flow Rate to a constant value (assuming 0.086162 m3/s, for a single
> > > zone), I don't understand why the output variable Zone Ventilation Volume
> > > Standard Density (hourly) is varying. Can someone explain it? I have
> > checked
> > > the settings and I have all minimum and maximum temperature setted to
> > > default value (this mean no shutoff of ventilation) , the maximum wind
> > speed
> > > is 40 m/s (no shutoff) and only the constant term coeeficient is set to 1,
> > > the other are to 0. Of course, I have tested this setting for a single
> > zone,
> > > without any infiltration or other air system.
> > >
> > > Thanks in advance.
> > >
> > > Robin GENOUD
> > >
> > >
> > >
> > > ------------------------------------
> > >
> > > Primary EnergyPlus support is found at:
> > > http://energyplus.helpserve.com or send a message to
> > > energyplus-support@
> > >
> > > The primary EnergyPlus web site is found at:
> > > http://www.energyplus.gov
> > >
> > > The group web site is:
> > > http://groups.yahoo.com/group/EnergyPlus_Support/
> > >
> > > Attachments are currently allowed but be mindful that not everyone has a
> > > high speed connection. Limit attachments to small files.
> > >
> > > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > > Documentation link and press the "search" button.
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > ------------------------------------
> > >
> > > Primary EnergyPlus support is found at:
> > > http://energyplus.helpserve.com or send a message to
> > > energyplus-support@
> > >
> > > The primary EnergyPlus web site is found at:
> > > http://www.energyplus.gov
> > >
> > > The group web site is:
> > > http://groups.yahoo.com/group/EnergyPlus_Support/
> > >
> > > Attachments are currently allowed but be mindful that not everyone has a
> > > high speed connection. Limit attachments to small files.
> > >
> > > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > > Documentation link and press the "search" button.
> > > Yahoo! Groups Links
> > >
> >
> >
> >
> >
> > ------------------------------------
> >
> > Primary EnergyPlus support is found at:
> > http://energyplus.helpserve.com or send a message to
> > energyplus-support@
> >
> > The primary EnergyPlus web site is found at:
> > http://www.energyplus.gov
> >
> > The group web site is:
> > http://groups.yahoo.com/group/EnergyPlus_Support/
> >
> > Attachments are currently allowed but be mindful that not everyone has a
> > high speed connection. Limit attachments to small files.
> >
> > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > Documentation link and press the "search" button.
> > Yahoo! Groups Links
> >
>
I think my last problrm comes from the Actuator Node of the OutdoorAir Mixer of my loop. In fact, I have an Outdoor Air Node for Actuator Node (called Outdoor Air Inlet Node). When I look at the features of this node (current density, temperature, pressure) they are the same as the oudoor air, which is what I want. But when I look at this Node MassFlowRate, I have a constant value and the flow seams to be calculated with a constant density of 1.1704 kg/m3. I don't understand why EE+ doesn't take the current outdoor air density to calcul the MassFlow. I have uploaded my file, called venti_ailloop_1zone.idf
Thanks in advance.
Robin
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "rgen1202" <robin.genoud@...> wrote:
>
> Lixing,
>
> I am aware of this density calculation. But I am still surprized of the way EnergyPlus model the ventilation(and the infiltration too) because if I model the mechanical ventilation with an Air Loop containing one exhaust fan constant volume and a 100% OA mixer, I get a constant Mechanical Ventilation Volume Standard Density. Therefore, the MassFlowRate in this case isn't calculated with the outdoor air density but with the standard density and I don't understant why.
>
> In fact, I am interested in the building energy consumption, and I don't know which model is the more accurate, since I have a significative difference in the cooling load due to outdoor air.
>
> Robin
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@> wrote:
> >
> > Robin:
> >
> > This is caused by air density calculations using different pressures,
> > temperature, and humidity ratio.
> >
> > In the calculation subroutine, the mass flow rate is required in the
> > calculations and is equal to the volumetric flow rate from your input times
> > air density as a function of outdoor conditions (T, P, and W). In the report
> > subroutine, the volumetric flow is calculated using the mass flow rate
> > divided by the air density as a function of standard condition. The
> > different densities are used in calculation and reporting. That is why you
> > see minor differences shown in outputs.
> >
> > Hope this helps.
> >
> > Lixing
> >
> > -----Original Message-----
> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of rgen1202
> > Sent: Wednesday, May 04, 2011 3:17 PM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > Subject: [EnergyPlus_Support] Re: ZoneVentilation Volume Standard Density
> > vary
> >
> > Lixing,
> >
> > Thanks for your answer. I uploaded the file in Files>Problem_Submittals
> > http://tech.groups.yahoo.com/group/EnergyPlus_Support/files/_Problem_Submitt
> > als/.
> > Its called ventilation_mech.idf . Its a single zone building with only
> > ZoneVentilationDesign Flow Rate. I used the FRA_LYON_IWEC.epw for the
> > weather (I uploaded it too).
> >
> > Thanks in advance.
> >
> > Regards.
> >
> > Robin
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@> wrote:
> > >
> > > Robin:
> > >
> > > If you report Zone Ventilation Volume Standard Density, it should give you
> > a
> > > constant value. Please upload the input file and tell us the weather file
> > > name if this weather file is downloaded from the energyplus web site. We
> > > will take a look.
> > >
> > > Lixing
> > >
> > > -----Original Message-----
> > > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Lixing Gu
> > > Sent: Wednesday, May 04, 2011 1:29 PM
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > Subject: RE: [EnergyPlus_Support] ZoneVentilation Volume Standard Density
> > > vary
> > >
> > > Robin:
> > >
> > > I think you may use one of two output variables to report volume flow
> > rates:
> > >
> > > HVAC,Sum,Zone Ventilation Volume Flow Rate Current Density [m3/s]
> > > HVAC,Sum,Zone Ventilation Volume Flow Rate Standard Density [m3/s]
> > >
> > > It was found as a bug to report volume flow rates and was fixed for the
> > next
> > > release. It is a report error and has no impact of simulation results.
> > >
> > > Lixing
> > >
> > > -----Original Message-----
> > > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of rgen1202
> > > Sent: Wednesday, May 04, 2011 11:56 AM
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > Subject: [EnergyPlus_Support] ZoneVentilation Volume Standard Density vary
> > >
> > > Hello,
> > >
> > > I have a question about the ZoneVentilation DesignFlowRate.When I set the
> > > Design Flow Rate to a constant value (assuming 0.086162 m3/s, for a single
> > > zone), I don't understand why the output variable Zone Ventilation Volume
> > > Standard Density (hourly) is varying. Can someone explain it? I have
> > checked
> > > the settings and I have all minimum and maximum temperature setted to
> > > default value (this mean no shutoff of ventilation) , the maximum wind
> > speed
> > > is 40 m/s (no shutoff) and only the constant term coeeficient is set to 1,
> > > the other are to 0. Of course, I have tested this setting for a single
> > zone,
> > > without any infiltration or other air system.
> > >
> > > Thanks in advance.
> > >
> > > Robin GENOUD
> > >
> > >
> > >
> > > ------------------------------------
> > >
> > > Primary EnergyPlus support is found at:
> > > http://energyplus.helpserve.com or send a message to
> > > energyplus-support@
> > >
> > > The primary EnergyPlus web site is found at:
> > > http://www.energyplus.gov
> > >
> > > The group web site is:
> > > http://groups.yahoo.com/group/EnergyPlus_Support/
> > >
> > > Attachments are currently allowed but be mindful that not everyone has a
> > > high speed connection. Limit attachments to small files.
> > >
> > > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > > Documentation link and press the "search" button.
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > ------------------------------------
> > >
> > > Primary EnergyPlus support is found at:
> > > http://energyplus.helpserve.com or send a message to
> > > energyplus-support@
> > >
> > > The primary EnergyPlus web site is found at:
> > > http://www.energyplus.gov
> > >
> > > The group web site is:
> > > http://groups.yahoo.com/group/EnergyPlus_Support/
> > >
> > > Attachments are currently allowed but be mindful that not everyone has a
> > > high speed connection. Limit attachments to small files.
> > >
> > > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > > Documentation link and press the "search" button.
> > > Yahoo! Groups Links
> > >
> >
> >
> >
> >
> > ------------------------------------
> >
> > Primary EnergyPlus support is found at:
> > http://energyplus.helpserve.com or send a message to
> > energyplus-support@
> >
> > The primary EnergyPlus web site is found at:
> > http://www.energyplus.gov
> >
> > The group web site is:
> > http://groups.yahoo.com/group/EnergyPlus_Support/
> >
> > Attachments are currently allowed but be mindful that not everyone has a
> > high speed connection. Limit attachments to small files.
> >
> > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > Documentation link and press the "search" button.
> > Yahoo! Groups Links
> >
>
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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