Re: [EnergyPlus_Support] Internal Mass approximations

I think it is advisable to include the effects of the internal thermal mass. But I treat carpets and furniture differently.

Carpet should go as an internal layer of your floor construction but the question is how much of the floor is covered by the carpet.

Carpets because of different thermal characteristics compared to uncarpeted floor constructions (e.g. heavy concrete floors) changes the dynamic response of the floor and the zone. For example it could reduce the the peak load hour of a zone by an hour.

When it comes to furniture you can model as internal mass and it is always difficult to find a representative thermo-physical properties for furniture. In EnergyPlus internal masses don't require details geometry inputs but one needs to be careful what type of interior solar distribution model to specify.

hope this helps,

Bereket Nigusse

From: "James V Dirkes II, PE" <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Sent: Fri, February 25, 2011 7:14:02 AM
Subject: RE: [EnergyPlus_Support] Internal Mass approximations

Getting there?.

So far no one has addressed the question of how to model internal mass from carpet, furniture, equipment and internal walls (or whether to bother).
I think that perhaps not only the mass, but surface area may be a factor?  any thoughts from thee E+ community?

Thanks to all!

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of James V
 Dirkes II, PE
Sent: Thursday, February 24, 2011 3:16 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Internal Mass approximations

Thanks to several of you for the suggestion to use the Zone objectâ??s Multiplier field.  Zone Multiplier, it seems, will multiply all of the walls and windows as well as the internals, so that will work.

As the risk of being too picky?.
I prepare geometry and materials
 information in DesignBuilder because Iâ??d go crazy trying to keep track of all those vertices on my own. DesignBuilder makes it very easy to give my clients a nice 3D image of their building as part of the report!  Itâ??s something like comfort food; they may not understand all of the technical details, but it sure looks like their building and gives an extra dose of confidence that the technical part is correct. (which it is!)

If I make one intermediate floor and multiply all of its zones, my 3D image will look rather squat compared to the 12 story real thing.  So, now that Iâ??ve realized a criteria that I forgot to mention the first time around (having a representative 3D image) ? is there a way to do that?

Thanks for your patience!

p.s., Linda, I could not find anything in my Tips and Tricks doc after going through all 39 pages.  The IO Ref works, though.

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450
 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Linda Lawrie
Sent: Thursday, February 24, 2011 2:38 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Internal Mass approximations

Check out the topic on "using zone multipliers" in the Tips and Tricks document.

At 12:33 PM 2/24/2011, James V Dirkes II, PE wrote:

May I have another hint, please?

Searches in the Help
 files for â??Space multiplierâ??, â??Spacemultiplierâ??, and â??multiplierâ?? donâ??t bring up anything useful?.

Thanks!

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [ mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Karen Walkerman
Sent: Thursday, February 24, 2011 2:25 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Internal Mass approximations

In this case you use a "space multiplier"
On Thu, Feb 24, 2011 at 2:23 PM, jvd2pe < jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Dear E+ forum, To date, I have not tried to combine zones on different
floors. Instead, I model separate zones for each floor. As I begin a 12
story structure model, I realize that the energy model will produce
essentially the same results if I 