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Re: [EnergyPlus_Support] Glass Facade
I'm sorry but I already discarded the files for the trombe wall simulations. However I can give you more details for the failure with creating two seperate zones.
Imput data:
As you recommended I created two window to make the double glass facade. Since I was not considering transfer of air between teh air cavity (between the two glass walls) and the room I opted for a SIMPLE airflow model. All simulations were conducted for Chicago climate. I studied the simulation for:
Zone Window Heat Gain, ZOne Transmitted Solar, Window Transmitted Solar, Surface Inside Temperature, Mean Air Temperature.
The program did not compute valuess for Window Transmitted Solar - for the glass wall facing the indoor space (hence inner glass wall). Moreover, I also compared simulation outputs for Surface Inside and Mean Air Temp with simulation outputs for a model with a single glass window (keeping all other parameters identical). I found that the double glass wall model provided lower indoor temperatures than the single glass wall model. This contradicts theorectical expectations.
Considering the above outputs I concluded that the inner glass wall does not interact with heat/light transmission and conduction in the simulation.
Hope this answers your questions.
Shefali
Simulation outputs:
"Michael J. Witte" <mjwitte@xxxxxxxx> wrote:First, if you have trombe wall input files that cause a crash, please
send them to energyplus-support@xxxxxxxx so we can determine what the
problem is.
Second, I do not understand what you mean when you say the "inner
(roomside) glass wall in a double glass facade does not interact with
the simulation".
Third, here is some input on the subject from one of the developers.
-----------------
Here is a summary of my limited experiences trying to model a double
skinned facade in EnergyPlus. I have a student here who is doing a
design thesis on this type of building envelope and we are hoping
that she will be able to model this in some way with EnergyPlus.
To date, our current experience is that it is possible to model
"something" but whether this is correct or not is another matter.
The approach that we took is to create a second zone for the second
glass facade. The inner glass wall is described as a window on the
surface between the facade zone and the inner zone. Sunlight will be
projected through the facade zone and into the next, though once it
arrives in the second zone it is considered to be all diffuse. As
long as the interzone surface and the window on that surface matches
in both zones, the simulation should run. If there are crashes,
chances are there is a problem with the input, though I won't
guarantee that there isn't something inside the code that will cause
problems.
We are also trying to take advantage of any heat build-up between the
facades in winter and ventilating the space between the facades in
summer. To get something very basic, we used a combination of the
simple ventilation statement and mixing statements. There is some
control here, but not much so one has to work within the confines of
those simple modeling statements. The link to COMIS might provide
more flexibility and/or better modeling of certain features (like the
stack effect), but we are not far enough along to test that just yet.
Creating an opaque wall that has the properties of glass will not
work as desired, because in EnergyPlus only a window surface will
transmit sunlight through to the inner zone. We have simulations
that run to completion (annual and design day), but we have not yet
thoroughly investigated the results.
-----------------
On 18 Dec 2002, at 8:47, Shefali Rajendra Modi wrote:
>
> The inner (roomside) glass wall in a double glass facade does not
> interact with the simulation. As a result even if the simulation may
> be completed, the simulation outputs are incorrect. A similar problem
> is found in other programs like Lightscape. I ran my simulations by
> making the gap between the two glass walls as a separate zone. When I
> tried simulating with a trombe wall, the simulation crashed
> repeatedly. You may want to try the simulations with 1. the use of
> COMIS and 2. creating a glass trombe wall.
>
> Hope this is helpful. I am very interested in this subject and I would
> appreciate if you will share the responses from other members and the
> outcome of your research with me.
>
> Shefali
>
> --------------------------------------------------------
> Shefali Modi
> M.Sc. Architecture, Environmental Technology
> Art and Architecture Building 2094
>
> On Wed, 18 Dec 2002, Alexander Beisteiner wrote:
>
> > Dear EnergyPlus User
> > It is possible to simulate trombe walls, but is it also possible to
> > simulate a double glass facade. In that case the difference to a
> > trombe wall would be that the masonry is replaced by a glass wall.
> > Further, does E+ account for a stack effect if there is vertical
> > temperature gradient? I am looking forward to your reply. Regards
> > Alexander
> >
> > __________________________________
> > DI (FH) Alexander Beisteiner
> > Forschungs- und Technologietransfer
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> > Fax: 0043/3357/45370/1010
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