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Re: [EnergyPlus_Support] Digest Number 4749
Not sure why you say the Jury is out on that. Internal
mass is not a physical entity in the zone. It won't see direct
solar.
It will absorb (heat/solar) from other surfaces.
At 08:33 AM 1/21/2015, Holly Samuelson hollywas@xxxxxxxxx
[EnergyPlus_Support] wrote:
Dear Jeannie, Ned, and
Linda,
Thank you very much for your input. Yes, I was trying to figure out
if my internal mass area would see direct solar or not. It sounds
like the jury is still out on that one, so I will experiment. The E+
literature does not seem to go into any more detail. Thanks
again.
Best,
Holly
Holly W.
Samuelson
DDes | LEED
AP+ |
AIA
Assistant Professor
Harvard Graduate School of Design
On Sunday, January 18, 2015
6:36 AM, "EnergyPlus_Support@xxxxxxxxxxxxxxx"
<EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
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4 Messages
Digest #4749
1a
Re: Internal Mass with "FullInteriorAndExterior" Solar
Distribution by "Edward G. Lyon" nedlyon01
1b
Re: Internal Mass with "FullInteriorAndExterior" Solar
Distribution by "Linda Lawrie" lklawrie
1c
Re: Internal Mass with "FullInteriorAndExterior" Solar
Distribution by "jeannieboef@xxxxxxxxx" jeannieboef
2a
Re: how to get the longwave radiation emitted from a surface due to
by "jeannieboef@xxxxxxxxx" jeannieboef
Messages
1a
Re: Internal Mass with
"FullInteriorAndExterior" Solar Distribution
Sat Jan 17, 2015 6:53 am (PST) . Posted by:
As I understand it, the internal mass object does not see direct solar
gain. I have also found that it is sensitive to area defined. That means
you canâ??t just make a random object with total mass you want to
simulate. The mass object should have the surface area of what you are
representing.
Ned Lyon, P.E. (MA, WV)
Staff Consultant
SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
617.285.2162 mobile
781.907.9009 fax
www.sgh.com
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[
mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Friday, January 16, 2015 5:44 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx;
EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_ Support] Internal Mass with "FullInteriorA
ndExterior" Solar Distribution Model
Dear EnergyPlus_Support,
Please excuse the accidental cross-posting.
I am trying to understand how the internal thermal mass (aka
"InternalMass& quot;) is being handled in my EnergyPlus models.
On page 222 of the EnergyPlus Input-Output Reference it states,
"simplifying calculations using internal mass must be used with
caution when the "FullInteriorA ndExterior" Solar Distribution
model is chosen.
Could anyone kindly help me understand what "use caution"
means? Does that mean that my internal thermal mass does not
"see" the solar radiation potentially hitting it (which might
realistically be the case for certain interior elements if they are
always in shade)? However, would you assume that this internal mass is
still exposed to the indoor air, and thus could still be absorbing or
emitting heat in that way?
Many thanks for any guidance.
Best,
Holly
Holly W. Samuelson, DDes, LEED, AIA
Assistant Professor Harvard Graduate School of Design
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1b
Re: Internal Mass with
"FullInteriorAndExterior" Solar Distribution
Sat Jan 17, 2015 11:01 am (PST) . Posted by:
I think the "use with caution" means when you use
the "FullInteriorAndExterior" solar distribution
model -- and lump internal partitions into
"Internal Mass" then places inside the zone would
see solar gain where they wouldn't if the
internal parititions were modeled as surfaces.
At 07:53 AM 1/17/2015, 'Edward G. Lyon'
eglyon@xxxxxxx [EnergyPlus_Support] wrote:
>As I understand it, the internal mass object
>does not see direct solar gain. I have also
>found that it is sensitive to area
>defined. That means you canât just make a
>random object with total mass you want to
>simulate. The mass object should have the
>surface area of what you are representing.
>
>Ned Lyon, P.E. (MA, WV)
>Staff Consultant
>SIMPSON GUMPERTZ & HEGER
>781.907.9000 main
>781.907.9350 direct
>617.285.2162 mobile
>781.907.9009 fax
>www.sgh.com
>
>From: EnergyPlus_Support@xxxxxxxxxxxxxxx
>[
mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
>Sent: Friday, January 16, 2015 5:44 PM
>To: EnergyPlus_Support@xxxxxxxxxxxxxxx;
EnergyPlus_Support@xxxxxxxxxxxxxxx
>Subject: [EnergyPlus_ Support] Internal Mass with
>"FullInter iorAndExterior&q uot; Solar Distribution
Model
>
>
>Dear EnergyPlus_Support,
>Please excuse the accidental cross-posting.
>
>I am trying to understand how the internal
>thermal mass (aka "InternalMass& quot;) is being
>handled in my EnergyPlus models. On page 222 of
>the EnergyPlus Input-Output Reference it states,
>"simplifyi ng calculations using internal mass
>must be used with caution when the
>"FullInter iorAndExterior&q uot; Solar Distribution model is
chosen.
>
>Could anyone kindly help me understand what "use
>caution" means? Does that mean that my internal
>thermal mass does not "see" the solar radiation
>potentially hitting it (which might
>realistically be the case for certain interior
>elements if they are always in shade)? However,
>would you assume that this internal mass is
>still exposed to the indoor air, and thus could
>still be absorbing or emitting heat in that way?
>
>Many thanks for any guidance.
>Best,
>Holly
>
>Holly W. Samuelson, DDes, LEED, AIA
>Assistant Professor Harvard Graduate School of Design
>
>
>
>
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1c
Re: Internal Mass with
"FullInteriorAndExterior" Solar Distribution
Sat Jan 17, 2015 1:51 pm (PST) . Posted by:
The internalmass object uses a user defined area for calculations.
Geometrically, it's not really there in the zone. So I think e+ uses
the area for an approximated convection and radiation heat exchange.
Convection is not so important, as it exchanges with the zone air
node. Radiation is a bit more complicated. With which surfaces should
it exchange radiation and to what extent? How much surface should
receive direct beam? Internal mass usually represents things standing
on the floor and infalling direct beam mostly lands on up-facing
surfaces. So I assume e+ looks at the user entered surface area, makes
some approximations. I don't know what those are, but if I were to
guess, I would guess that it receives all direct beam except for the
portion that is smaller than the floor. I would guess that the
reflected fraction is equally proportioned to all the other zone
surfaces except the floor. And that long wave infrared radiation
exchange is also equally proportioned to all surfaces except the
floor.
If these aspects are important for your model, then I would not rely
on my guessing. Check the documentation or if it's not there, the
code. Or ask the helpdesk. The forum you've asked.
The "caution" should be more apparent. Why bother simulating
detailed
internal reflections and radiation exchange when it's all getting
proportioned anyway. So basically you loose this accuracy.
Not a very helpful answer, I guess.
Mit freundlichen Grü�en- Sent from my iPhone (excuse the
brevity)
i. A.
Jean Marais
b.i.g. bechtold
Tel. +49 30 6706662-23
On 16.01.2015, at 23:43, "Holly Samuelson hollywas@xxxxxxxxx
[EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>
wrote:
> Dear EnergyPlus_Support,
> Please excuse the accidental cross-posting.
>
> I am trying to understand how the internal thermal mass (aka
> "InternalMass& quot;) is being handled in my EnergyPlus
models. On page
> 222 of the EnergyPlus Input-Output Reference it states,
"simplifying
> calculations using internal mass must be used with caution when the
> "FullInteriorA ndExterior" Solar Distribution model is
chosen.
>
> Could anyone kindly help me understand what "use caution"
means?
> Does that mean that my internal thermal mass does not
"see" the
> solar radiation potentially hitting it (which might realistically be
> the case for certain interior elements if they are always in
> shade)? However, would you assume that this internal mass is still
> exposed to the indoor air, and thus could still be absorbing or
> emitting heat in that way?
>
> Many thanks for any guidance.
> Best,
> Holly
>
> Holly W. Samuelson, DDes, LEED, AIA
> Assistant Professor Harvard Graduate School of Design
>
>
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Posted by: Linda Lawrie <linda@xxxxxxxxxxxxxx>
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