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Re: [EnergyPlus_Support] Re: How do you disable modulation of opening factors?

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Re: How do you disable modulation of opening factors?
From: Lixing Gu <gu@xxxxxxxxxxxx>
Date: Thu, 07 Sep 2006 16:06:06 -0400
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The window opening with the temperature control option (ventilation control 
mode) is determined by the temperature difference between indoor and 
outdoors only. It is possible that a window is opened in a minute and closed 
at the next minute, because the minimum system time step is a minute. The 
AirflowNetwork model does not consider any opening duration.

I looked at your input file. The two opposite windows belong to two 
different zone. Since the window opening is determined by the temperature 
difference between a zone and outdoors, two windows will not open at the 
same time if two zones have different temperatures.

Although you have options to select a ventilation control mode, you only can 
select one of them, not both, such as constant and temperature control 
options. If yes, what is a logic?

Thanks.

Lixing Gu


----- Original Message ----- 
From: "colotupper" <kendra.tupper@xxxxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Thursday, September 07, 2006 11:16 AM
Subject: [EnergyPlus_Support] Re: How do you disable modulation of opening 
factors?


> Thanks for explaining that!
>
> It's a little strange that the decision of whether or not to open the
> windows occurs on a minute by minute basis (this is how it appeared
> when I output in detailed mode).  It would be nice if there was a
> control that could force the windows to be either open or closed for
> at least a half an hour (or something other time chunk) to avoid the
> unrealistic modelling of windows being opened and closed every minute
> based on temperature conditions.
>
> Also, I am trying to model cross ventilation, but the opposite windows
> are not always opening at the same times.  Is there any way to model
> ventilation with temperature control and force the windows to open
> simultaneously?  I am guessing this has to be done with the constant
> control mode and a schedule, but then the windows are opened
> regardless of the outdoor air temperatures.
>
> Thanks,
>
> Kendra
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@...> wrote:
>>
>> Kendra:
>>
>> What you have done is right to make all opening factors either 0 or 1.
>> Output results are also right at "timestep" report frequency.
>>
>> There are two timesteps used in EnergyPlus: zone time step and
> system time
>> step. The zone time step is your input from the TIMESTEP IN HOUR
> object. The
>> system time step is used internally and is determined by zone
> temperature
>> difference between previous timestep and current timestep. If the
> difference
>> is more than 0.3C, the system time step is shorter than the zone
> time step.
>> The AirflowNetwork model is performed at the system timestep level.
> If you
>> use "detailed" reprt frequency, you can see opening factors are
> either 0 or
>> 1.0. When "timestep" reprot frequncey is used, the opening factors
> are gived
>> as an average value over a zone timestep when system time step <
> zone time
>> step. That is why you see opening factors vary between 0 and 1.0.
>>
>> Please let me know if you have more concerns.
>>
>> Lixing Gu
>> Florida Solar Energy Center
>>
>> ----- Original Message ----- 
>> From: "colotupper" <kendra.tupper@...>
>> To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
>> Sent: Wednesday, September 06, 2006 9:12 PM
>> Subject: [EnergyPlus_Support] How do you disable modulation of opening
>> factors?
>>
>>
>> >I am simulating Natural Ventilation with Airflow Networks and my
>> > Ventilation Control Mode = Temperature.  I want to have only 2
>> > conditions: closed windows (opening factor = 0) and open windows
>> > (opening factor = 1).  I have set Limit Value on Multiplier for
>> > Modulating Venting Open Factor = 1, and all opening factors equal to 1
>> > as well.
>> >
>> > For some reason, when i output hourly results, my Opening Factor and
>> > Opening Factor Multiplier for Venting Modulation  vary between 0
> and 1.
>> >
>> > I read past messages about this problem and tried changing my
>> > timesteps and reporting frequency, but this had no effect.  Right now,
>> > I have my timestep set to 1 and my report frequency set to timestep.
>> > I also tried letting all of the fields default to disable the
>> > modulation, but this had no impact either.
>> >
>> > I am going to post this file - if anyone has any suggestion, I would
>> > greatly appreciate it!
>> >
>> > Thanks,
>> >
>> > Kendra
>> >
>> >
>> >
>> >
>> >
>> >
>> > 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 not allowed -- please post any files to the
> appropriate
>> > folder in the Files area of the Support Web Site.
>> >
>> > EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf
> and press
>> > the "search" button.
>> >
>> > Yahoo! Groups Links
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>>
>
>
>
>
>
>
>
> 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 not allowed -- please post any files to the appropriate 
> folder in the Files area of the Support Web Site.
>
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press 
> the "search" button.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
>
> 




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References:
- [EnergyPlus_Support] Re: How do you disable modulation of opening factors?
  - From: colotupper

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