Re: [EnergyPlus_Support] Re: Output analysis : Zone Air Balance Surface Convection Rate

[Lixing Gu <gu@xxxxxxxxxxxx>]

Camille:

Your observation is correct. The difference is caused by time lag. The zone 
temperatures used in the Surface Int Convection Heat Rate calculations are 
the values at the previous zone time step. The zone temperatures used in the 
Zone Air Balance Surface Convection Rate calculations are the values at the 
current time step.

Lixing Gu
----- Original Message ----- 
From: "le_carambar" <le_carambar@xxxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Tuesday, July 14, 2009 8:51 AM
Subject: [EnergyPlus_Support] Re: Output analysis : Zone Air Balance Surface 
Convection Rate


>I did new comparaison and sometimes it matches sometimes it doesn't 
>matches...
>
> In fact, it matches when the temperature of the zone is constant, and as 
> soon as there is temperature variation values become differents.
>
> In order to simplify the problem, I study a zone without any windows :
> - 4 interzone surfaces : N, E, S, O.
> - 1 floor
> - 1 roof
>
> And I compared the sum of each "surface int convection heat rate" to the 
> "zone air balance surface convection rate"...
>
> According to the definition of "zone air balance surface convection rate" 
> (The Zone Air Balance Surface Convection Rate is the sum, in watts, of 
> heat transferred to the zone air from all the surfaces), I though it 
> should match.
>
> There is probably a point I misunderstand !
>
> Thanks,
>
> Camille T.
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> 
> wrote:
>>
>> I should have also told you that convection from window frames and
>> dividers ARE ALSO included in the Zone Air Balance Surface Convection
>> Rate report variable (but not the glazing). So the comparison you are
>> making would not add up exactly if window frames and dividers are used.
>> If there are no window frames or dividers (or no windows at all), I
>> would think the numbers should match.
>>
>> Richard Raustad wrote:
>> >
>> >
>> > If you want to know the definition of any report variable, search for 
>> > it
>> > in the Input Output Reference document. Here is what I found:
>> >
>> > The Zone Air Balance Surface Convection Rate is the sum, in watts, of
>> > heat transferred to the zone air from all the surfaces. This field is
>> > not multiplied by zone or group multipliers.
>> >
>> > I don't think that Window Convection Heat Gain from Glazing to Zone is
>> > included in the Zone Air Balance Surface Convection Rate. Leave the
>> > glazing gain out and see if the numbers match up better.
>> >
>> > le_carambar wrote:
>> > >
>> > >
>> > > Dear users,
>> > >
>> > > I try to understand what is include in the output variable : Zone Air
>> > > Balance Surface Convection Rate.
>> > >
>> > > I did the sum of the "Surface Int Convection Heat Rate" for every
>> > > surfaces (1 ext wall, 3 interzone surfaces, 1 roof, 1 floor) and
>> > > "Window Convection Heat Gainfrom Glazing to Zone". And the result is
>> > > not the same value than "Zone Air Balance Surface Convection Rate".
>> > >
>> > > I check output variable "Window Gap Convective Heat Flow" and "Window
>> > > Convection Heat Gain from Gap between Shade and Glazing to Zone " but
>> > > they are equal to 0.
>> > >
>> > > Can you help me ?
>> > >
>> > > thanks,
>> > >
>> > > Camille T.
>> > >
>> > >
>> >
>> > -- 
>> > Richard A. Raustad
>> > Senior Research Engineer
>> > Florida Solar Energy Center
>> > University of Central Florida
>> > 1679 Clearlake Road
>> > Cocoa, FL 32922-5703
>> > Phone: (321) 638-1454
>> > Fax: (321) 638-1439 or 1010
>> > Visit our web site at: http://www.fsec.ucf.edu 
>> > <http://www.fsec.ucf.edu>
>> >
>> > UCF - From Promise to Prominence: Celebrating 40 Years
>> >
>> >
>>
>> -- 
>> Richard A. Raustad
>> Senior Research Engineer
>> Florida Solar Energy Center
>> University of Central Florida
>> 1679 Clearlake Road
>> Cocoa, FL  32922-5703
>> Phone:   (321) 638-1454
>> Fax:     (321) 638-1439 or 1010
>> Visit our web site at: http://www.fsec.ucf.edu
>>
>> UCF - From Promise to Prominence: Celebrating 40 Years
>>
>
>
>
>
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