Tall Bldg Pressurization & Stack Effect

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Is COMIS still active? How is it used within EnergyPlus? Can it be used to evaluate building pressurization and stack effect infiltration in multiuse (retail, office, hotel with fixed windows and apts at the top with operable windows) tall and super-tall bldgs (ex. 160 storey Burj Khalifa and proposed Jeddah Kingdom Tower)? Can ESPr and IESVE be used to evaluate bldg pressurization and stack effect infiltration in super-tall bldgs? Is CONTAM linked with an energy program?

Varkie Thomas's picture
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I don't think CONTAM is currently related to any energy program.

Pallavi Mantha, LEED AP BD+C

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About ESP-r and tall buildings....

I know of no one who has attempted a super-tall building with ESP-r flow network. I was asked
one time about analysis of stack approaching 800m and my response then and now is that
this is SO FAR beyond the underlying correlations and research that a cautious
approach should include a substantial test and calibration phase.

The mind-boggling number of leakage points would also be worth considering. Can
we safely ignore some classes of penetrations and facade faults? Are
crack models in current tools valid for the extreme pressure differences one might
encounter? It might require some new component representations.

And then there is the non-trivial issue that simulation tools work with single climate
files - over that vertical distance one might reasonably expect there to be
several different weather patterns (temperatures, wind speeds and directions)
and so it might be necessary to adapt tools to deal with multiple sets of boundary
conditions. And there might be rapid fluctuations, so hourly weather patterns is
unlikely to provide a rich enough set of disturbances.

And most network flow codes assume that air is incompressible. That 'shortcut' helps
the solution and probably does little damage in models of moderate complexity
and it might not be valid in the context of super-tall.

Conceptually it might work and I would say there are a lot of caveats to resolve
and probably a substantial investment needed to be able to confidently approach
such projects. And the teams that have implemented super tall buildings also
will have skills and methods that us mortals do not.... Not territory for novices.

Regards, Jon Hand

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As I understand it Comis is credited in the e+ documentation and portions
of it appear to be used but the airflow network is largely a new model.
I have heard that some trnsys users use comis still.
Chris

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Thanks for responses. A group in Chicago is trying to evaluate air pressures and air movement in tall bldgs. Burj Khalifa in Dubai is 162 floors and 828 meters tall and the apt floors with operable windows are the top - http://skyscrapercenter.com/dubai/burj-khalifa/ A proposed bldg is going to be taller (1,000 meters?).

The attached preliminary Excel calculation sheet is my attempt to understand the issues of multi-use (retail, office, hotel, apartments, restaurants, services, etc.) high rise bldg. I think the analysis should be based on vertical zones by floor usage type and floors served by a mechanical floor. The air handling systems have to deal with infiltration due to stack effect of the vertical zones that they serve.

I have tried looking at CONTAM but I think it is too detailed for evaluating the performance of tall bldgs as a whole. I think we need to develop a simpler modeling and simulation system for this purpose which can be linked to energy programs.

Varkie
http://www.iit.edu/arch/faculty/thomas_varkie.shtml

Sent Wednesday, May 2, 2012 4:17 pm
To "thomasv at iit.edu"
, "bldg-sim at lists.onebuilding.org"

Subject RE: [Bldg-sim] Tall Bldg Pressurization & Stack Effect

About ESP-r and tall buildings....

I know of no one who has attempted a super-tall building with ESP-r flow network. I was asked
one time about analysis of stack approaching 800m and my response then and now is that
this is SO FAR beyond the underlying correlations and research that a cautious
approach should include a substantial test and calibration phase.

The mind-boggling number of leakage points would also be worth considering. Can
we safely ignore some classes of penetrations and facade faults? Are
crack models in current tools valid for the extreme pressure differences one might
encounter? It might require some new component representations.

And then there is the non-trivial issue that simulation tools work with single climate
files - over that vertical distance one might reasonably expect there to be
several different weather patterns (temperatures, wind speeds and directions)
and so it might be necessary to adapt tools to deal with multiple sets of boundary
conditions. And there might be rapid fluctuations, so hourly weather patterns is
unlikely to provide a rich enough set of disturbances.

And most network flow codes assume that air is incompressible. That 'shortcut' helps
the solution and probably does little damage in models of moderate complexity
and it might not be valid in the context of super-tall.

Conceptually it might work and I would say there are a lot of caveats to resolve
and probably a substantial investment needed to be able to confidently approach
such projects. And the teams that have implemented super tall buildings also
will have skills and methods that us mortals do not.... Not territory for novices.

Regards, Jon Hand

Varkie Thomas's picture
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COMIS (or parts of it) still seem somewhat active in Europe. EMPA and
Transsolar built COMIS into a version of the TRNSYS building model. For
a time, COMIS with a graphical interface was offered as a commercial
product that could either stand alone or be coupled with the TRNSYS
building model. Recently EMPA and CSTB, who had been maintaining COMIS
in Europe decided to go open source with the engine
(http://tech.groups.yahoo.com/group/comis/message/982)

As for CONTAM, it can stand alone or be coupled with the TRNSYS building
model as well.
Best,
David

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David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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We will soon be able to offer wind speed and direction at about every 250 M
of altitude for anywhere if this helps.

Best, 

Chuck Khuen

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I think the vertical zoning of the air handling and stack pressure
developed within is a minor consideration compared to the lift shafts
and stairs. I haven't worked on anything higher than 40 or so
floors. At 162 if you have HR lifts with no transfer floor then the
stack pressures will be 4 times that of a 40 storey building assuming
conventional theory. You will get a big draft when doors open and
close but maybe that isn't a problem.

I don't know if stairs go all the way up these buildings but I assume
in such buildings stair rises are either split vertically and / or not
allowed for normal inter floor communication within tenancies.

In my experience (with <50 storeys) the mechanical systems can deal
with the pressure fluctuations fairly well as the fan curves are
typically steep so can take a pressure fluctuation with minor changes
in flow. The issues I assume will be doors manually opened and closed
that connect a floor with a large vertical void (stair) and trying to
keep differential pressures below 5 Pa or so so people can actually
open them.

Would be interesting to hear whether you find this to be a major
energy problem for the building. My guess is it will be minor but
then I have worked in temperate climates. I think the issues are
likely to be getting stairs (doors people can open) and lifts to work
(people not being faced with a stiff breeze as they enter or leave a
lift car) and that if you manage that then any energy problem goes
away. The aperture issues Jon refers to will exist but conventional
theory for steady state conditions should allow you to bound the
issues (not definitive but informative) and then probably CFD to
validate conditions in time. Bulk airflow as Jon has said would
probably require calibration / validation due to the difference in
pressures you are likely dealing with.

Interesting topic where we all need to be careful of the limits of
simulation ...

Regards,
Graham

hamnmegs at ozemail.com.au's picture
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FYI.

Wind speeds at 200+ meters can be complex,especially if there is a shear layer, and/or any sort of terrain variations.

One suggestion is to see if you can find anyone has done a MM5 model for this location, calibrated to on-site met towers.

Also, the wind energy folks have a lot riding on this sort of thing and the weather modelers routinely simulate this with their 40 layer wind models. NREL, NCAR and NOAA has a lot of expertise in this as well.

There are also specialty consultants who do this for a fee, I believe the WMO has lists of respected firms internationally. Within ASHRAE you'd consult TC 4.2.

Academics in this area include meteorology Depts at Penn State and TAMU for starters.

Jeff S. Haberl, Ph.D., P.E., FASHRAE

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I would like to have comments and suggestions on this issue particularly if the attached views & conclusions are wrong and there are mistakes in the analysis & calculations.

(First 3 files are attached):
?1 ? NIST-CONTAM-Library - Enclosure Surface Leakage at Elevation Temperature Pressure?;
?2 - Infiltration in Multi-Use Tall-Bldgs due to Stack-Effect & Wind-Press ? Excel Program?;
?3 - Advantages and Limitations of the Excel Program - Tall Buildings Infiltration ? V.C. Thomas?
?4 - Barbara A. Nadel, FAIA - 21st Century Building Envelope Systems - Architectural Record? http://continuingeducation.construction.com/article.php?L=38&C=235

Varkie Thomas
http://www.iit.edu/arch/faculty/thomas_varkie.shtml

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