Re: [TRNSYS-users] Exterior wall against ground

[David Bradley <bradley@tess-inc.com>]

Abdullahi,
  You are correct that you should integrate with respect to depth
and calcuate the average. There is no simple way to do that directly in
Type77/501 at the moment. It is an interesting idea for future versions.
As a simple alternative, you can use the Kasuda depth for the middle of
the below grade section of the wall although it is not quite as
correct.
Cheers,
 David


At 12:27 4/13/2007, aa1@brighton.ac.uk wrote:

David/Daniel,
 
My only concern with the use of Kasuda correlation (in the form used in type 77 &Type 501) for vertical surfaces like a basement wall, is the fact that these components will only give the soil temperature at a single vertical point (say depth Z,Z₁,Z₂ ?..at any given time). If your wall is very deep, say 1-2m deep, what you need is probably the average temperature of a vertical profile ranging between depth Z₁ and Z_2.
 
The way to go about this is to integrate the Kasuda _expression_ with respect to depth (Z₁ to Z₂). My question to David is whether this is achievable with Type77/501? If not perhaps Daniel might want to look at the following document on how to integrate the Labs/kasuda correlations.
 
Labs, K. 1989. Earth Coupling. Passive Cooling. J. Cook. Cambridge Massachusetts, The MIT Press: 197-346.
 
Abdullahi
 
School of the Environment
University of Brighton
Cockcroft Building
Lewes Rd.
Brighton
BN2 4GJ
 
Tel: +44 01273 643455
 
-----Original Message-----
From: David Bradley [ mailto:bradley@tess-inc.com]
Sent: 13 April 2007 17:38
To: Büchele Daniel (Helbling Beratung + Bauplanung); trnsys-users@engr.wisc.edu
Subject: Re: [TRNSYS-users] Exterior wall against ground
 
Daniel,
  Arie's response is quite correct. Additionally, if you do not want to use the annual ambient temperature as your boundary wall temperature, you can use the temperature of undisturbed ground as calculated by the Kasuda correlation from Type77. This makes the ground temperature a function of depth and time of year. Like with Arie's response, it assumes that the ground is an infinite source / sink and that energy transferred from the building through the wall to the ground does not affect the ground temperature in the long term. We have written a few basement models recently that do account for the change in the ground temperature due to energy transfer through the wall but they assume four basement walls and a floor. If you only have one wall below grade then you might be best off using Arie's method either with the annual average ground temperature or with Type77.
Cheers,
 David


At 12:48 4/12/2007, Helbling Beratung + Bauplanung wrote:

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Hello everybody

Can anyone, tell me whats the best way to simulate a external wall against the ground.
How can I define the ground ??

Thanks in advance

Mit freundlichen Grüssen / Kind regards

Daniel Büchele
Dipl. Ing. Gebäudeklimatik- / Technik
Projektleiter

Helbling Holding AG
Hohlstrasse 614
CH-8048 Zürich
Telefon +41 44 438 18 64
Mobile  +41 79 641 44 03
Telefax +41 44 438 18 10
mailto:daniel.buechele@helbling.ch < http://www.helbling.ch >

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****************************************************************************************
Thermal Energy System Specialists (TESS), LLC
David BRADLEY                           2916 Marketplace Drive - Suite 104
Partner                                        Madison, WI 53719
Phone: (608) 274-2577 USA
Fax: (608) 278-1475
E-mail: bradley@tess-inc.com
Web Pages:  http://www.tess-inc.com     and      http://www.trnsys.com

"Providing software solutions for today's energy engineering projects"
****************************************************************************************