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Srishti,<br>
<br>
This is nothing out of the ordinary. Just use E+ standard
fenestration objects. <br>
<br>
You're using Window. My approach would be to build up my glazing in
Window, check it's performance and then manually transfer its
performance data to the objects WindowMaterial:Glazing,
WindowMaterial:Gas & Construction. There does appear to be an
option to link with Window via Construction:WindowDataFile. I have
not tried this yet.<br>
<br>
Best of luck<br>
<br>
Chris<br>
<br>
On 12/05/2011 08:51, srishti srivastava wrote:
<blockquote
cite="mid:BANLkTimOyLxkbmrt-xhoBv4CQN4wm1eXtQ@mail.gmail.com"
type="cite">
<pre wrap="">Thanks to all,
I would like to clarify the approach i have taken in the study at this
point of time.
The Building which is modelled is a sqaure block. There are five zones
(four aligned in the cardinal directions and one in the centre), the
depth of the zone is till 15 feet from the facade in each cardinal
direction.
Firstly, I am considering a glazed facade here, which might be either
monolithic(one layer of glass) or Insulated Glazed Units (Double
layers of glass 6 mm thick with an air gap of 12 mm sandwitched
between them ). It is not a load bearing structure.There is no
insulation separately used in the facade.
Secondly, the glass is attached to the subframe which is subsequently
attached to the main frame(both of which are aluminium). Or it can be
directly attached to main frame.
In short, the facade which needs to be simulated is not an opaque
construction. Infact, it is fully glazed since i m considering a
window wall ratio as high as 90 percent also as one of the variables
in the study.
Thus, the question remains to be the same.
How to model curtain wall or rather curtain glazed facades in Eplus?
How will the modelling for such type of facade be different from
modelling a regular window?
I really appreciate the time spent and effort made by people reading
and replying to the thread.
Srishti.
On 5/11/11, Chris Yates <a class="moz-txt-link-rfc2396E" href="mailto:chris.malcolm.yates@gmail.com"><chris.malcolm.yates@gmail.com></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi Pedro,
Thanks for this - it's good to be up to date with the latest E+
developments and this is a significant one.
I'm not certain Srishti was asking about ventilated facades in the first
instance. I just threw it in there in my first response and the thread
has seemed to grow into a "ventilated facades" discussion!
Best regards
Chris
On 10/05/2011 14:47, Pedro Peixeiro wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hello everyone.
Chris,
That limitation isn't present anymore. Solar radiation is partially
absorbed by the interzone ceilling and floor (and eventually walls if
present) but calculation is carried out to transmit the remaining
diffuse and direct radiation into the subsequent zone. Reflections are
also taken into account. But limitations still persist about shading
devices:
1) they cannot be specificied to occupy just a fraction of the glazing
area (fully deployed or no shading at all);
2) they can only be mounted on windows of exterior walls (though this
allows to model the shading device before, after and in between double
glazed windows of the exterior pane, it can't be be modeled for
shading devices on the inner pane, room side;
3) there is still some limitations regarding airflow and convection
coefficient control between the shading device and the glazing itself,
because Eplus considers the shading device as a layer of the window it
is mounted on, and no direct control can be done for that in-between
window/shade air gap (this also prevents output results for the
interior window surface of the outside pane, only outside surface
temperature and shading temperature can be obtained).
Srishti,
So like it has been said, if you plan on simulating ventend facades in
which the inside pane is opaque, you can model them using the Exterior
Natural Vented Cavity object present in Eplus. If not, my advice is to
setup your facade as a vertical stack of two or more zones divided by
virtual partitions. Using Airflow Network objects, you can define all
the air dampers you need on the outside pane and also the ventilation
that occurs across the virtual partitions. Use Full Interior and
Exterior Solar Distribution with Reflections (remember to keep your
zone convex), choose a proper inside convection algorithm for the
cavity (I suggest ISO 15099 Windows), and you should come across some
relatively close results, considering the complexity of the problem
itself.
Pedro.
On 10-05-2011 12:32, Francisco Massucci wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Srishti,
Here is the entire text. My ctrl+C, Ctrl+v failed last time, sorry.
*SIMULATING DOUBLE SKIN FACADE*
I'm simulating an office with a double skin façade using the
"exterior vented natural cavity."
The façade is naturally ventilated and has Venetian blinds in the
gap. The blinds are exposed to solar
radiation and, during the day, they can reach very high temperatures
which may affect the temperature of the air in the gap and/or the
performance of the glass façade. Does EnergyPlus take into
account these two effects?
*Answer*
The exterior vented natural cavity model is for *opaque* surfaces
only and does not apply to glazing
systems. There is a model for blinds in the window gap that takes
those two things into account, but I
am not sure if it works together with the air flow window model.
*Question*
Thanks for your answer. I compared two simulations, one with the
façade as exterior vented cavity
and the other with the façade as a simple window, and it seemed that
solar transmission through the
glazing system is the same in both the cases. Even if the exterior
vented cavity is only for opaque
surfaces do you think it is possible to use the model for a glass
façade, using as input the data of the
glazing system (thermal emissivity and solar absorbtivity)? Which
differences or errors would occur
using that model?
*Answer *
If I understand you correctly, I think what you are actually getting
in the model is a regular window
surrounded by a wall with a double skin. See if the inside face wall
surface temperatures are different.
The window shouldn't be changing.
The exterior vented cavity model, which assumes that all the solar is
blocked by a thin, solid layer on
the outside, cannot be used for glazing. Opaque means no
transmission. Inside EnergyPlus this
becomes a special boundary condition for surface heat transfer
modeling that is not available for
window modeling. The window still gets exterior environment boundary
conditions even though its
parent surface has the exterior cavity boundary condition.
Double façade improvements are being planned for the future.
*Possible Workaround *
if you really wanted to use the exterior vented cavity model on your
DF, it could apply to a case where
the double façade has totally opaque shades that are closed tight.
You would use regular materials in
the construction for the surface that approximate the DF (no
subsurface and no glazing materials).
The baffle in the exterior cavity model can get quite hot and then
re-radiate infrared (but no
shortwave) and convect to the underlying surface. But note that air
gap models are much better
developed for windows than for regular constructions; you would have
to come up with thermal
properties for each layer. One advantage of this approach might be a
better model of transient
behavior because the window models are always steady state.
See also: EnergyPlus Technical Note – Opaque Ventilated Façades (July
2007 User News)
On May 28, 2007, Emanuele Naboni (PhD Candidate), a visiting
researcher from the Politecnico di
Milano (Italy) gave a lecture at Lawrence Berkeley National
Laboratory on how he used EnergyPlus to
model Ventilated Opaque Façades. A .pdf of his presentation is
available at
<a class="moz-txt-link-freetext" href="http://SimulationResearch.lbl.gov/reports.html">http://SimulationResearch.lbl.gov/reports.html</a> under the heading "All
EnergyPlus Reports."
To save time, here is the direct link:
<a class="moz-txt-link-freetext" href="http://simulationresearch.lbl.gov/dirpubs/vent_facade.pdf">http://simulationresearch.lbl.gov/dirpubs/vent_facade.pdf</a>
Francisco Massucci.
On Tue, May 10, 2011 at 8:21 AM, Francisco Massucci
<<a class="moz-txt-link-abbreviated" href="mailto:massucci@gmail.com">massucci@gmail.com</a> <a class="moz-txt-link-rfc2396E" href="mailto:massucci@gmail.com"><mailto:massucci@gmail.com></a>> wrote:
Srishti,
Try to found a topic named "Double Facades" on bldg-sim list. I
asked the same question some time ago. The major problem in this
cases ,is the heat loss by convection inside de facade, because
otherwise it will percfectly work as a thin zone.
I found something on google, someone asking for an energyplus's
developer:
/I'm simulating an office with a double skin façade using the
"exterior vented natural cavity." /
/The façade is naturally ventilated and has Venetian blinds in
the gap. The blinds are exposed to solar /
/radiation and, during the day, they can reach very high
temperatures which may affect the temperature of the air in the
gap and/or the performance of the glass façade. Does EnergyPlus
take into /
/account these two effects? /
/Answer /
/The exterior vented natural cavity model is for *opaque*
surfaces only and does not apply to glazing /
/systems. There is a model for blinds in the window gap that
takes those two things into account, but I /
/am not sure if it works together with the air flow window model./
/
/
Please let me know if you do some progress. I'm from Brazil and
our climate conditions are very similar.
Good Luck,
Francisco Massucci
On Tue, May 10, 2011 at 5:10 AM, Chris Yates
<<a class="moz-txt-link-abbreviated" href="mailto:chris.malcolm.yates@gmail.com">chris.malcolm.yates@gmail.com</a>
<a class="moz-txt-link-rfc2396E" href="mailto:chris.malcolm.yates@gmail.com"><mailto:chris.malcolm.yates@gmail.com></a>> wrote:
Srishti,
I have no experience of the Therm/ LBNL Window link that you
speak of but as long as you're happy with working within the
limitations of the E+ shading calculation you should be fine.
I'm not sure of the latest E+ but the main historical
limitation I'm aware of is that solar gain to a zone is
absorbed by the floor (with some specific exceptions). This
is expedient for most simulation tasks but will not suffice
if you wish to model solar penetrating through subsequent
zones (within a double sheet facade, where the cavity is
modelled as a zone for example). The E+ documentation is
extensive and covers this in detail.
There are a number of options for the type of solar calc
undertaken. There are also options for convection
coefficient. You may find both of these affect results and
simulation time.
Good luck
Chris
On 10/05/2011 06:58, srishti srivastava wrote:
</pre>
<blockquote type="cite">
<pre wrap=""> Dear Friends,
I am Srishti Srivastava from India. My research topic is related
to
evaluation of different types of facades in Indian context with
special reference to the modern glazed facades.
I am trying to simulate a building with curtain wall in Energy
Plus. I
know of one way of doing it through Window and Therm software
from
LBNL, although there are few issues in that. Is there any
alternative
way to simulate curtain wall in Energy Plus.
Does anyone have a prior experience of simulating curtain wall
in
Energy Plus. Can anyone help me in simulating a curtain wall in
Energy
Plus.
Thanks in advance.
Srishti Srivastava,
India.
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</pre>
</blockquote>
<pre wrap="">
--
Chris Yates C Eng MCIBSE
/Building Physics Consultant/
Tel:+447960731576
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<pre wrap="">
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</pre>
</blockquote>
<pre wrap="">
--
Chris Yates C Eng MCIBSE
/Building Physics Consultant/
Tel:+447960731576
Email: <a class="moz-txt-link-abbreviated" href="mailto:chris.malcolm.yates@gmail.com">chris.malcolm.yates@gmail.com</a>
Skype: christopher.m.yates
</pre>
</blockquote>
</blockquote>
<br>
<div class="moz-signature">-- <br>
<div>
<p>Chris Yates <span style="color: rgb(79, 98, 40);">C Eng
MCIBSE</span></p>
<p><i style="">Building Physics Consultant<o:p></o:p></i></p>
<p>Tel:<span style=""> </span>+447960731576</p>
<p>Email: <a class="moz-txt-link-abbreviated" href="mailto:chris.malcolm.yates@gmail.com">chris.malcolm.yates@gmail.com</a></p>
<p>Skype: <span class="SpellE">christopher.m.yates</span></p>
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