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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>Graham,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>You can, within IES Virtual Environment, explicitly model blinds as
you have described below: <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>First either divide the vented façade into two zones (inner and
outer air spaces) with a corrugated surface or add such a partition to one zone;
every other facet of this corrugated surface will be a blind slat with
specified material properties and tilt angle, etc., and the facets in between
will be holes. Having completed this, if you made two zones to begin with, then
combine them as one zone with the blinds as floating partition or planar
surface elements. If you need to model the façade over the course of a year with
the louvers at dynamically varied angles or in various states of deployment, I’d
suggest multiple runs with post-processing to combine the data into a single
year. For this you would combine selected results based upon incident solar
gain for that hour, or whatever variable you choose to determine the control of
the louver angles, etc.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>It is important that you end up with a single combined zone between
the inner and outer glazing to ensure proper calculation of transmitted direct
and diffuse solar gain (however, you will still require separate vertically
stacked zones for each story, etc. of the building façade as means of
determining differences in buoyancy with MacroFlo). The thermal properties of
the blind materials and their surfaces will also be important to determining
the absorbed solar gain, re-radiation to the façade elements, and convective
heat transfer to the air in the vented cavity. Lastly, because the theory
applied in MacroFlo is based on the flow characteristics of openings that are
small in relation to the spaces they connect—i.e., it’s set up to account for
the flow resistance (aero drag coefficient) of operable windows, other punched
openings, etc.—you will need to have a look at Section 7: <b>Techniques for
Modeling Flow in Façades and Flues </b>in<b> </b>the <b>MacroFlo Calculation Methods
</b>section of the user manual. This will tell you how to adjust the dimensions
of your façade cavity model so that a MacroFlo opening at each floor height (or
similar) will appropriately account for resistance from openings, mullion protrusions,
catwalks, surface friction, and so forth.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>Regards,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>Timothy Moore,</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>Building Science Research and Performance Simulation</span><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:navy'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>Center for the Built Environment (CBE)</span><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:navy'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>University of California at Berkeley </span><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:navy'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'><a href="http://www.CBE.berkeley.edu"><span style='color:navy'>www.CBE.berkeley.edu</span></a></span><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#2B5395'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:green'>Sustainable Design Consultant, LEED AP<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:green'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:green'>Whole Systems Design</span><span style='color:navy'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:green'>Office: 510-525-4809</span><span style='color:navy'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:green'>Mobile: 303-324-1044</span><span style='color:navy'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:green'>eFax: 413-480-7252</span><span style='color:navy'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:green'><a href="mailto:tmoore@whole-systems-design.com"><span
style='color:blue'>tmoore@whole-systems-design.com</span></a></span><span
style='color:navy'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:green'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#2B5395'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:navy'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:navy'> </span><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:navy'><o:p></o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b>On Behalf Of </b>hamnmegs@ozemail.com.au<br>
<b>Sent:</b> Wednesday, April 02, 2008 1:15 AM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-sim] Modelling of Ventilated Facades with Cavity Blinds -
Blind Parameters<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Hi
all,</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>We
are revisiting ventilated facades with cavity blinds in an attempt to minimise
the fabric heat loads on a building. We are looking at internally and
externally ventilated options. My experience in this area is limited to
use of bulk airflow modelling (IES Apache or use of Arup's in house tools
during the time I worked for them).</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>We
have done some preliminary digging around to source the best software to
determine average annual performance, bulk temperatures etc recognising that
CFD will always have a place in understanding airflows and temperatures in more
detail. Our current position is:</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>1)
We explored the possibilities with Energy+ and the ventilated facade / cavity
model 2-3 years ago and were unable to generate results that we had
confidence in. In skimming the version updates it does not appear that
there has been further work on this module so we don't plan to go back to
Energy+.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>2)
We use IES Apache extensively but the blind inputs are indirect (unknown)
rather than direct (known) properties and thus lead to uncertainty (see below)</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>3)
We were initially encouraged by the ICE software out of Sweden, but now
understand that the blind inputs are similar to IES.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>IES
/ ICE take as input for the blind the a SHGC modifier (1 - SHGC = the
overall reflected component of the blind be it SW or LW radiation) along with
the proportion of this which ends up as shortwave versus longwave
radiation. There is also a U-Value / conductance modifier. The
blind can be incident solar or time controlled like most programs.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>We
would prefer to input blind transmittance and absorptance (or reflectance) and
let the software dynamically determine SHGC. Until you have an
understanding of the temperature of the blind which is a function of incident
solar radiation, ambient temperatures, cavity ariflow etc you won't know
exactly what the longwave radiation component is of the SHGC. So the egg
comes before the chicken ... . </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>In
short the longwave component of the blind SHGC is a strong function of other
dynamic or design variables and as such cannot be pre-determined with
confidence in our professional opinion.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Does
TRNSYS or other overcome this limitation? </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Any
suggestions? Any killer papers out there that have correlated longwave blind
SHGC to different glazing & blind types and ventilation
arrangements? for a variety of solar / ambient conditions ..... ? Anyone
considering a PhD in the near future in this area :)?</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Regards,</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Graham</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial Narrow","sans-serif";
color:#2053B7'>Graham Carter</span></strong><span style='font-size:10.0pt;
font-family:"Arial Narrow","sans-serif"'> |<strong><span style='font-family:
"Arial Narrow","sans-serif"'> Manager Sustainable Design</span></strong> |
<strong><span style='font-family:"Arial Narrow","sans-serif";color:#2053B7'>Lend
Lease design</span></strong></span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial Narrow","sans-serif"'>T 61 2 9236
6347 | F 61 2 9383 8124 | M 0407 949 193</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial Narrow","sans-serif"'>30
The Bond, 30 Hickson Road, Millers Point NSW 2000</span><span style='font-size:
10.0pt'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial Narrow","sans-serif";
color:black'>graham.carter@lendlease.com.au</span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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