[Bldg-sim] differences between energy simulations programs

Wed Mar 24 09:52:59 PDT 2010

Shaun

Certainly a reasonable conclusion -- if you assume the DOE software is
infallible.  I worked at a DOE national lab for 10 years.  They put
their pants on one leg at a time just like the rest of us.  That's where
I learned that engineers don't make mistakes.  They just have "events"
from which they "recover."  In the modeling study I commissioned after
leaving the DOE contractor job, we got the same result regardless of
whether we insulated the slab -- which was curious.  With the UCLA HEED
simulator, I got the best results with significant southern glazing --
which would support the passive solar idea.

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

-----Original Message-----
From: Shaun Martin [mailto:smartin at shaunmartinconsulting.com] 
Sent: Wednesday, March 24, 2010 11:30 AM
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

Hi Paul,

My experience on EnergyPlus with this question led me to the conclusion
that
the time-delayed release or gain of heat in interior concrete walls or
floors is a bit of a fiction.   Virtually all of this heat is picked
within
the first hour by the mechanical systems.   Exterior concrete, likewise,
had
very little impact on the occupant comfort and interior temperatures
simply
because of the presence of insulation.   However, remove the cooling
systems
(we do that here in Canada, particularly in residential high-rises) and
the
picture is very different.

It would be interesting to repeat the same analysis on a building that
is
fully designed to take advantage of passive heating and cooling. Few
are, of
course. I suspect even partially passive buildings (mixed/hybrid mode)
don't
experience even a fraction of the purported benefits of thermal mass.

The increase in the heating load is because the assembly is treated as
one
R-value. Removing the carpet decreases the R and increases the heating
load.

Shaun

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 8:36 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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