[Equest-users] Roof vs Exterior Wall Load

Thu Sep 8 08:49:36 PDT 2011

For what it's worth, the example LS-F report in the help file
documentation also shows only 0's in the roof component.  From within
eQuest, go to the Help menu, select DOE-2 Help.  Expand the "Volume 4:
Libraries & Reports" and then the "Reports" topics.  LS-E and LS-F are
under the loads reports.  The text says the monthly space components are
summed across spaces.  The definition of the LS-F report excludes plenum
spaces:

This report gives a breakdown of loads on a monthly basis for the entire
building, according to the source of the load. The loads in
unconditioned spaces (ZONE-TYPE = UNCONDITIONED or PLENUM) are not
included; all entries are in millions of Btu/month.

This just explains why they don't show up in the LS-F...I believe that
the mechanism used by eQuest to account for heat gain in the plenums is
to apply that heat gain to the return air before the system, thereby
increasing temperature, humidity, etc. in the RA stream due to the loads
in the plenum spaces connected to a given system.  Someone from Hirsch
can jump in if I got that wrong.

I'm curious if anyone else has dug deeper on this than I have, though?

Jeremy R. Poling, PE, LEED AP+BDC

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bruce
Easterbrook
Sent: Thursday, September 08, 2011 10:09 AM
To: Jonathan Smith
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Roof vs Exterior Wall Load

    To tell the truth I haven't a clue.  You would think the sums would
agree.  I did open one of my sim's and summed the roof components for
all my zones from the LS-E report and found the sum didn't match the
figure in the LS-F report, it was much higher.  I rarely use these
reports and hadn't noticed this before.  eQuest does treat roofs as
horizontal walls but on my sim I know I didn't do any modifications
which might have mixed things up.  I took a look at the "Detailed
Simulation Reports Summary" and there was nothing which stood out as an
explanation.  So the quickest thing to do is pass this back to the group
to see if we can find an answer.
Bruce

On 08/09/2011 09:33 AM, Jonathan Smith wrote: 

Hi Bruce:

Thanks you for your reply. 

The LS-F report I'm reviewing is a building wide report which should be
inclusive of all spaces. As stated previously, MBTUs through ROOF
components is listed as zero. However, the space level report (LS-E) for
the one of the plenums with a roof component shows heat loss of the roof
component. This is true for some of the other plenum spaces. Any ideas
why the space level report (LS-E) ROOF components are not reported on
the building wide report (LS-F) as roof components?

Jonathan

From: Bruce Easterbrook [mailto:bruce5 at bellnet.ca] 
Sent: Wednesday, September 07, 2011 9:08 AM
To: Jonathan Smith
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Roof vs Exterior Wall Load

In the room space the roof is actually the ceiling.  Because the room
and plenum spaces are close or the same temperature there is minimal or
no heat loss between them.  You need to go to the plenum space for the
heat loss through the exterior roof.  If you want the heat loss for the
full floor to floor space you have to add the room and plenum losses.
The plenum will have some wall surfaces as well.
Bruce Easterbrook P.Eng.
Abode Engineering

On 06/09/2011 01:46 PM, Jonathan Smith wrote: 

RE: Detailed Report, LS-F Building Monthly Load Components 

Why would roof heat losses be zero in a model defined with plenum spaces
that have roofs components? In report LS-F, there are no losses reported
in 'Roof' and 'Wall' heat losses seem exceptionally high, as if 'Roof'
losses are reported in 'Walls'. 

All spaces were created using the eQuest wizard mode. Inspecting the
"exterior surface properties", the word "Roof" appears below the surface
name. All roof constructions are made with layers input, having a
U-Value 0f 0.043. When creating exterior surfaces in detailed edit mode,
no option exists for defining an exterior surface as a roof or wall. 

So, how are the loads associated with roofs reporting in LS-F? What
other reasons might roof loads not report, or at least not report in the
correct load component?

Jonathan R. Smith AIA LEED(r)AP

40 Beaver Street
Albany, New York 12207
p: 518.463.8068 x268
f: 518.463.8069 
www.csarchpc.com <http://www.csarchpc.com/> 

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