[Equest-users] Thermal mass effects --- of stuff (UNCLASSIFIED)

[Julien Marrec]

Jeff,

In E+ there's also an "InternalMass" objec. It is listed under the group
"Thermal Zones and Surfaces". It only asks for a construction, a zone name,
and its surface (m² / ft²): might be easier.

>From the I/O reference:

*Internal Massis used to specify the construction/material parameters and
area of items within the space that are important to heat transfer
calculations but not necessarily important geometrically. (For example,
furniture within the space – particularly for large spaces).*

John,

Both e+ and equest can have internal mass objects, that you can add/or
customize.

E+ having no defaults on the subject, it won't take any internal mass into
account unless you tell it to.

eQuest has by default some internal mass: Floor-weight and Furniture. For
Furniture - default is FURN-WEIGHT = 2 lb/ft² of floor area - compare that
to what you think you have in your garage and you'll see the difference :))

I think an even bigger problem is to use external walls (especially in
equest where it's so easy...) defined only by R-value as opposed to
layer-by-layer, thus with no thermal mass...

I'm pretty sure as a general rule we tend to underestimate the overall
thermal mass.
On the subject, I remembered Joe Huang (Joe, I hope you don't mind me
quoting you) making a comment about DOE2 making "lighter" models than real
anyway so you have to "boost up the internal mass considerably beyond
what's there to get  the floating temperature profiles to match measured
temperatures" (see his post here
<http://lists.onebuilding.org/htdig.cgi/bldg-sim-onebuilding.org/2015-January/046078.html>
)

Best,
Julien


> Le 17 juin 2015 à 20:20, "Eurek, John S NWO" <John.S.Eurek at usace.army.mil>
a écrit :
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> General question:
>
> Do any energy models take into account the thermal mass of stuff?
>
> Then extreme case I know about is a garage.  When my garage was empty and
I turned on the heater it heated up fairly quickly.  When I brought in my
truck, tools, shelves, etc. (a few tons of steel) it took a lot lot longer
to get warm.
>
> This is an extreme case, but the same thing would happen in every type of
building on some level.
>
> -----Original Message-----
> From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On
Behalf Of Jeff Haberl
> Sent: Wednesday, June 17, 2015 10:39 AM
> To: Peter Schonherr; equest-users at lists.onebuilding.org
> Subject: [EXTERNAL] Re: [Equest-users] Thermal mass effects of interior
walls
>
> Hello Peter,
>
>
>
> Create layered walls with the materials you intend to simulate and then
set the floor weight = 0 to trigger custom weighting factors. You may have
to fiddle with the interior convection/radiation coefficient to get a
meaningful “connection” to the room air node.
>
>
>
> Jeff
>
>
>
> 8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  8=()  8=)  8=|  8=)  :=')  8=) 8=?
> Jeff S. Haberl, Ph.D.,P.E.inactive,FASHRAE,FIBPSA,......jhaberl at tamu.edu
<mailto:........jhaberl at 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, 77843..............................URL:
www.esl.tamu.edu
> 8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=)  :=)  8=)  8=!  8=)  8=? 8=) 8=0
>
>
>
> From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On
Behalf Of Peter Schonherr
> Sent: Wednesday, June 17, 2015 10:26 AM
> To: equest-users at lists.onebuilding.org
> Subject: [Equest-users] Thermal mass effects of interior walls
>
>
>
> Hello,
>
>
>
>      Is it possible to model the effects of thermal mass of interior
walls? if so, how is that done?
>
>
>
> Peter Schonherr
>
>
>
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
>
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to
EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20150618/39f10d5a/attachment-0005.htm>