[Bldg-sim] differences between energy simulations programs

[Nick Caton]

Paul,

 

I would like to console/assure you of something, just because any given
energy model doesn't show specific behavior doesn't mean it's not real,
and it doesn't mean the person who put that model together doesn't
"believe" in it.  More often than not, the program simply can't handle
what we're trying to model explicitly/cleanly, if at all!  The science
of building energy modeling is ever-developing.  Every month new
software and methods are developed that allow us to grow and accurately
model more things.

 

Speaking specifically to eQuest, I can't purport to be an expert - as
I've yet to be tasked to model thermal massing options comparatively,
but I'm aware explicitly modeling the thermal massing qualities of any
given zone's contents/floor constructions is a possibility (see attached
screengrab - rightmost inputs).  The constructions you define for your
envelope walls/floors/roofs and interior walls also defines the mass
properties that, by default, will account for the storage and transfer
of heat over time - though users can and often do choose to model such
elements without heat storage/transfer if necessary for tangent reasons.
That said, my general impression from reading others' discussions on the
topic (in the eQuest mailing list), is that when it comes to comparative
modeling of specific constructions (i.e. carpeted SOG vs. bare slabs),
it does become fuzzy as to how to accurately model both cases.

 

John,

 

If I can venture a guess for Shaun... I think it has something to do
with long hours, caffeine overdosage, deadlines, model reviewers, and
the quirky but pleasant company/support available through these mailing
lists...  Also, what was the question? =)

 

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of John
Aulbach
Sent: Sunday, March 28, 2010 12:37 AM
To: Shaun Martin; Paul Grahovac; Clark Denson; Eurek, John S NWO;
Peterson, John (EYP/HP CFS); bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] differences between energy simulations programs

 

I would like to know the meaning of modelers getting sidetracked
easily....

 

________________________________

From: Shaun Martin <smartin at shaunmartinconsulting.com>
To: Paul Grahovac <paul.grahovac at prosoco.com>; Clark Denson
<cdenson at ssr-inc.com>; "Eurek, John S NWO"
<John.S.Eurek at usace.army.mil>; "Peterson, John (EYP/HP CFS)"
<jpeterson at hp.com>; bldg-sim at lists.onebuilding.org
Sent: Wed, March 24, 2010 2:39:49 PM
Subject: Re: [Bldg-sim] differences between energy simulations programs


Paul, back to your original question, this document may help.  There is
also
a document with a side-by-side comparison table, somewhere. I'll see if
I
can find it and send it to you.

If you've been reading through bldg-sim, you'll find modellers tend to
get
sidetracked easily. 


Shaun Martin LEED AP
Principal
Shaun Martin Consulting
Suite 200 - 420 West Hastings Street
Vancouver, BC  V6B 1L1
c: 604-789-1095
e:smartin at shaunmartinconsulting.com
member CAGBC, ASHRAE 


-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Paul
Grahovac
Sent: Wednesday, March 24, 2010 1:06 PM
To: Clark Denson; Eurek, John S NWO; Peterson, John (EYP/HP CFS);
bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] differences between energy simulations programs

I don't know what methodology my people used.  I appreciate everyone's
input. I am concerned I should remain a viewer and not a participant on
this
listserv since I am not a modeler -- only a consumer of modeling
services.
One data point that is not data, but confirmed to me that thermal mass
is
real:  I brought an energy auditor to an minimally-heated greenhouse at
night and asked him to point his thermographic gun at everything
--including
the concrete blocks holding up the planting platforms.  Everything was
blue
and cold except the concrete blocks which were yellow-red warm.

Paul Grahovac, LEED AP
PROSOCO, Inc.
785-393-1816 cell

-----Original Message-----
From: Clark Denson [mailto:cdenson at ssr-inc.com]
Sent: Wednesday, March 24, 2010 2:40 PM
To: Paul Grahovac; Eurek, John S NWO; Peterson, John (EYP/HP CFS);
bldg-sim at lists.onebuilding.org
Subject: RE: [Bldg-sim] differences between energy simulations programs

The way I understand it, the effect of thermal mass is all in how the
heating/cooling loads are calculated.  TRACE is unique from many other
programs in that the user can choose the heating/cooling load
methodology
that will be used.  Depending on your choice, thermal mass will be
calculated differently.  Most incorporate some kind of Transfer Function
Method (TFM), and each method is based on calculations and algorithms
from
ASHRAE publications such as the 1972, 1985, and 2001 ASHRAE Fundamentals
Handbooks, ASHRAE Research Project #359, and the ASHRAE Toolkit for
Building
Load Calculations.

So the question of "What are the differences between TRACE and Energy
Simulation program 'X'?" is complicated by the additional question,
"Which
Load Calculation Methodology in TRACE did you select?"

Clark Denson, PE


-----Original Message-----
From: Paul Grahovac [mailto:paul.grahovac at prosoco.com]
Sent: Wednesday, March 24, 2010 10:36 AM
To: Eurek, John S NWO; Peterson, John (EYP/HP CFS);
bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] differences between energy simulations programs

FYI, another comment on TRANE Trace 700:  the modeling engineers I hired
told me, after consultation with TRANE, that exposed interior concrete
floors, when modeled against the ASHRAE baseline of carpeted floors,
showed
a reduction in the cooling load, but an increase in the heating load.
An
increase in the heating load was contrary to my reading in passive solar
books.  I used a simplified simulator for lay people, and it showed
exposed
interior concrete floors improved cold-weather performance over carpeted
concrete (HEED, www2.aud.ucla.edu/heed).

I have since heard that TRANE does not model thermal mass well.  I have
also
not been able to find anyone with experience modeling the thermal mass
of
interior exposed concrete floors using any simulation tool.

Paul Grahovac, LEED AP
PROSOCO, Inc.
785-830-7355

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Eurek, John
S
NWO
Sent: Wednesday, March 17, 2010 3:32 PM
To: Peterson, John (EYP/HP CFS); bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Discrepancy between Equest & Trace 6.2

John,

It is like buying a car.  Do you want a truck, manual/automatic,
something
fast.......  You are asking for information overload.  If you know
exactly
what you want it may be easier for us (in this list) to help guide you
to
the best option.

I also was once curious and found the link below.  The end of the paper
has
charts comparing different features.
http://apps1.eere.energy.gov/buildings/tools_directory/pdfs/contrasting_
the_c
apabilities_of_building_energy_performance_simulation_programs_v1.0.pdf 

Another sight.
http://www.wbdg.org/resources/energyanalysis.php


I use Trace 700 (v6.2.4).  Why? Because the first, second and third
company
I worked for used it.  It is good for running loads, but so-so for
energy
modeling.  Also I have never used anything else.  I have looked at
equest
and DOE, they both look like learning a completely new programming
language.


I wouldn't mind hearing other people's brief views of the programs they
use.
Equest, DOE, HAP, ect.



John Eurek LEED AP
Mechanical Engineer,
US Army Corps of Engineers
Omaha District CENWO-ED-DA
1616 Capitol Avenue
Omaha, NE 68102
Phone: (402) 995-2134
email: john.s.eurek at usace.army.mil


-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Peterson,
John
(EYP/HP CFS)
Sent: Wednesday, March 17, 2010 2:03 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Discrepancy between Equest & Trace 6.2



Has there been any information released on the differences between
energy
simulation programs?  We have a bid requirement with a certain
percentage
listed and we have been asked to address the differences between the bid
model and the newly proposed model.  



Thanks in advance -

John



John Peterson, PE, LEED AP

HP Critical Facilities Services delivered by EYP

6600 Rockledge Drive, 4th Floor

Bethesda, MD  20817

cell: 202-731-5835 



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