[Bldg-sim] Tall Bldg Pressurization & Stack Effect

Graham Carter & Megan Lyall hamnmegs at ozemail.com.au
Fri May 4 15:41:09 PDT 2012


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

On 04/05/2012, at 12:00 AM, Varkie C Thomas wrote:

> 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
>
> From 	Jon Hand <jon at esru.strath.ac.uk>
> Sent 	Wednesday, May 2, 2012 4:17 pm
> To 	"thomasv at iit.edu" <thomasv at iit.edu> , "bldg-sim at lists.onebuilding.org 
> " <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
>
> From: bldg-sim-bounces at lists.onebuilding.org [bldg-sim-bounces at lists.onebuilding.org 
> ] On Behalf Of Varkie C Thomas [thomasv at iit.edu]
> Sent: 02 May 2012 20:01
> To: bldg-sim at lists.onebuilding.org
> Subject: [Bldg-sim] Tall Bldg Pressurization & Stack Effect
>
> 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?
>
> <Bldg-Pressurization - Stack-Effect - Wind- 
> Press 
> .xlsx><thomasv.vcf>_______________________________________________
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