[bldg-sim] Apache uni-dimensional heat transfer assumption

[Pueltz, Gunter]

Dear Chris,

I recommend you to perform some detailled FEM-calculations combined 
with CFD-Sims for typical corners of your building and afterwards 
you can adjust the 1-D heatflux of related walls by varying the external 
heat transfer coefficients; for that you can increase the external 
heat transfer coefficient either for convection and/or for
thermal radiation (emissivity of external surface) .....

As a more sophisticated alternative you can also use a simulation tool,
which shows the
facility of 3-D-heat conduction within a wall. As far as I know this
facility is available in the software package ESP-r of Joe Clark, ESRU, ....

Regards,
Gunter


> -----Original Message-----
> From: bldg-sim at gard.com [mailto:bldg-sim at gard.com]On Behalf Of Yates,
> Christopher
> Sent: Friday, September 16, 2005 4:07 PM
> To: bldg-sim at gard.com
> Subject: [bldg-sim] Apache uni-dimensional heat transfer assumption
> 
> 
>  ASPAM=antispamwpk42
> 
> Thanks Gunter,
> 
> Are you aware of any guidance for adjusting this external 
> heat transfer
> coefficient (I assume you mean surface emissivity) to account for such
> things as thermal bridging at corners?
> 
> I'll take the comments regarding Apache's thermal radiation 
> model on board -
> thank you very much.
> 
> Regards, Chris
> 
> -----Original Message-----
> From: Pueltz, Gunter [mailto:GPueltz at MuellerBBM.de] 
> Sent: 16 September 2005 14:52
> To: 'christopher.yates at halcrowyolles.com'; bldg-sim at gard.com
> Subject: RE: [bldg-sim] Apache uni-dimensional heat transfer 
> assumption
> 
> Dear Chris,
> 
> the error caused by the 1-D heat conduction of very thick walls can be
> minimized by an adjusted (higher) external heat transfer coefficient.
> 
> But be aware of following fact:
> The main problem with Apache is that the thermal radiation 
> model is a simple
> "mean-radient-model" (like TRNSYS), which is not very 
> accurate, and not a
> more sophisticated model based upon view-factors (like ESP-r, 
> Eplus, TAS,
> etc.).
> Thus the errors induced by the minor radiation model will 
> exceed the errors
> caused by restricted 1D heat conduction extensively .......
> 
> Regards,
> Gunter
> 
> --------------------------------------------
> Dr. Gunter Pültz
> Müller-BBM GmbH
> Robert-Koch-Straße 11
> 82152 Planegg
> Telefon +49 (0)89 85602 - 336
> Telefax +49 (0)89 85602 - 111
> http://www.MuellerBBM.de 
> 
> 
> > -----Original Message-----
> > From: bldg-sim at gard.com [mailto:bldg-sim at gard.com]On Behalf 
> Of Yates, 
> > Christopher
> > Sent: Friday, September 16, 2005 3:35 PM
> > To: bldg-sim at gard.com
> > Subject: [bldg-sim] Apache uni-dimensional heat transfer assumption
> > 
> > 
> > Dear All,
> > 
> > The thermal analysis package Apache (from IES) is a multi 
> zone model 
> > type analysis package, utilising finite difference methods to model 
> > building performance against weather data. One of the 
> assumptions that 
> > it makes is that heat transfer only occurs between adjacent 
> spaces in 
> > a direction normal to the adjacent surfaces. I believe that 
> this is a 
> > common assumption for most building sim software (e.g. ESP-r).
> > 
> > The assumption holds true for traditional building types with 
> > constructions that are relatively thin when compared to the overall 
> > building volume.
> > 
> > However, we are analysing a building with wall 
> constructions that are 
> > quite thick when compared to the overall volume. Common 
> sense tells me 
> > that there will be a substantial 3 dimensional component to heat 
> > transfer.
> > 
> > Does anybody have any experience of modelling the thermal 
> response of 
> > extremely heavyweight buildings that could give me some 
> advice on the 
> > limitations of this type of software (it's a nuclear waste storage 
> > facility)?
> > 
> > It may be possible that this is the preserve of high end CFD, 
> > generating large amounts of transient data with the help of super 
> > computing facilities.
> > However, it is difficult to know this because of the 
> apparent lack of 
> > work done on modelling such facilities.
> > 
> > Facts/ opinions???!
> > 
> > Thank you in advance
> > 
> > Chris Yates
> > 
> > 
> > The contents of this email are confidential to the intended 
> recipient 
> > at the email address to which it has been addressed and do not give 
> > rise to any binding legal obligation upon Halcrow Group 
> Limited unless 
> > subsequently confirmed on headed business notepaper sent by fax, 
> > letter or as an email attachment. It may contain 
> confidential and/or 
> > privileged material and may not be disclosed to or used by anyone 
> > other than this addressee, nor may it be copied in any way. 
> If you are 
> > not the intended recipient, please email the sender immediately by 
> > replying to this message and delete the material from your system.
> > 
> > 
> > ======================================================
> > You received this e-mail because you are subscribed to the 
> > BLDG-SIM at GARD.COM mailing list.  To unsubscribe from this 
> mailing list 
> > send a blank message to BLDG-SIM-UNSUBSCRIBE at GARD.COM
> > 
> 
> 
> The contents of this email are confidential to 
> the intended recipient at the email address to 
> which it has been addressed and do not give rise 
> to any binding legal obligation upon Halcrow 
> Group Limited unless subsequently confirmed on 
> headed business notepaper sent by fax, letter 
> or as an email attachment. It may contain 
> confidential and/or privileged material and may 
> not be disclosed to or used by anyone other 
> than this addressee, nor may it be copied in 
> any way. If you are not the intended recipient, 
> please email the sender immediately by replying 
> to this message and delete the material from 
> your system.
> 
> 
> =====================================================You 
> received this e-mail because you are subscribed 
> to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe 
> from this mailing list send a blank message to 
> BLDG-SIM-UNSUBSCRIBE at GARD.COM
> 

===========================
You received this e-mail because you are subscribed 
to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe 
from this mailing list send a blank message to 
BLDG-SIM-UNSUBSCRIBE at GARD.COM