[bldg-sim] suggestions other than eQuest

Jeff Haberl jeffhaberl at tees.tamus.edu
Mon Apr 4 15:38:09 PDT 2005


Hello:

Actually, DOE-2 can do good job with thermal mass if one has custom
weighting factors and "effective" values for the internal
convection/radiation coefficient, and contact area. In a calibrated
CFD/DOE-3 simulation of a Buddhist temple in Thailand we got
remarkably-good results. 

See: Sreshthaputra, A., Haberl, J., Andrews, M. 2004. "Improving
Building Design and Operation of a Thai Buddhist Temple", Energy and
Buildings, Vol. 36,  pp. 481-494, for more details.

Unfortunately, this requires more time and resources than your average
human being will allow, and DOE-2 is still limited in its ground
coupling, unless you are using the latest instructions from Huang et
al., and you already have existing soil properties and ground
temperatures.

The biggest mistake that I see most people making with DOE-2 is using
quick calculations (i.e., entering a floor weight, and not using custom
weighting factors). In general quick calculat6ions lead to some very
strange interior temperatures.

Jeff

8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  8=()  8=)  8=|  8=)  :=')  8=)
8=)  8=?

Jeff S. Haberl, Ph.D.,
P.E.............................jhaberl at esl.tamu.edu

Professor......................................................Office
Ph: 979-845-6507

Department of Architecture.......................Lab Ph: 979-845-6065 

Energy Systems Laboratory.......................FAX: 979-862-2457 

Texas A&M University..............................77843-3581

College Station, Texas, USA.......................URL: www-esl.tamu.edu

8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=)  :=)  8=)  8=!  8=)  8=?  8=)
8=)  8=0 

 


-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com] On Behalf Of Blake,
Jeff
Sent: Sunday, April 03, 2005 10:03 AM
To: bldg-sim at gard.com
Subject: [bldg-sim] suggestions other than eQuest

Lee,

Doe2 (2.1 or 2.2) is not the right program for looking at heavy thermal
mass
buildings.  The limitation is a function of the thermal response factors
used to represent time-delayed heat transfer through opaque surfaces.
This
method is a legacy of the original DOE2 design requirements which were
somewhat hindered by slow computers.

You should use a simulation program that uses a more fundamental heat
balance approach.  There are several but I believe that ESP-r (ESRU,
University of Strathclyde) is one of the best.

Jeff Blake

-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com]On Behalf Of Lee Elson
Sent: Friday, April 01, 2005 3:55 PM
To: bldg-sim at gard.com
Subject: [bldg-sim] suggestions other than eQuest


I'm designing a 3500 sq foot residence at a 5000' desert-like elevation
(Nevada).
The site has good sun exposure and the climate is generally dry. Typical
temperatures in Feb are 20-40 F. The building is mostly oriented
east-west
and has
a 2' deep insulated rock floor (for thermal mass) with active air
recirculation.
ICF's will be used as well as tile over concrete (above rock floor) in
south
facing rooms.

I'm trying to get a realistic estimate of temperature swings and
auxiliary
heating
requirements. I've used eQuest, which seems pretty impressive and easy
to
use.
I've entered the floor plan layout, specified the glazing (clear glass
on
the
south side) and the building materials. The calculations are a bit
disappointing:
with 12% of the total floor space in south facing glass, the aux heating
required
is not too different (~20%) from a house with standard insulation and no
added
south facing glass. Another oddity: when I change the south facing glass
area from
5% of the available south wall to 90% of the south wall, I get an
*increase*
in
aux heating requirements. The eQuest developer thinks this is due to
inadequate
thermal mass/heat recirculation modeling.

I suspect that eQuest is not doing accurate modeling since other houses
with
a
similar design in this area get much better thermal performance. Can
anyone
suggest either software or a service provider that might be able to do a
more
accurate calculation?

TIA

Lee Elson




======================================================
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


===========================
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



More information about the Bldg-sim mailing list