[EnergyPlus_Support] Re: Thermal mass effect

["sm278424" <shaunmartin@xxxxxxx>]

Hi Mike,

We've discussed this building before. It has a CV supply air system + 
plenum and radiant ceiling panels. 

Answers
1. I tried defining all of my constructions as Regular-R to eliminate 
the mass. This increased the total cooling load by just under 5%.

2. I'm using a combination: furniture and internal partitions are 
internal mass, floors and ceilings are surface objects. Taking out 
the internal mass increased the total cooling load by just about 1%.

3. ORNL and Berkley Solar Group have done some interesting work here 
on external walls.  The location of the concrete (mass) and the 
magnitude of the daily temperature swings are the important factors. 

On internal surfaces, I found is that the interaction between the 
radiant ceiling panel and the concrete floor is something to pay 
attention to. Conceivably you could night-cool the building with this 
type of system.

4. Mostly by tracking the surface tempertures.

Shaun


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte" 
<mjwitte@g...> wrote:
> I don't have a good reference to offer, but I have some questions 
to ask:
> 
> 1.  The obvious question - are you using Material:Regular so that 
there is 
> actually mass present in the building?
> 
> 2.  Have interior surfaces been described using internal mass or 
surface 
> objects?
> 
> 3.  In a "fully conditioned" building, mass effects tend to be 
small, because 
> most of the mass is not changing temperature very much except 
during 
> transitions to/from thermostat setback.  This is especially true if 
the 
> building has a fairly large footprint and a large core to perimeter 
ratio.
> 
> 4.  How are you quantifying the "thermal mass effect"?
> 
> Mike
> 
> 
> On 1 Apr 2005, at 17:47, sm278424 wrote:
> 
> > 
> > 
> > In models I've been working with recently (of a fully air 
conditioned 
> > office building), the thermal mass effect seems quite small.  
> > 
> > Can anyone suggest a good reference on this topic? 
> > 
> > Thanks
> > Shaun
> > 
> > 
> > 
> > 
> > 
> > The primary EnergyPlus web site is found at:
> > http://www.energyplus.gov
> > 
> > The group web site is:
> > http://groups.yahoo.com/group/EnergyPlus_Support/
> > 
> > Attachments are not allowed -- please post any files to the 
appropriate folder
> > in the Files area of the Support Web Site.
> > 
> > Yahoo! Groups Links
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> 
> 
> 
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support      
> EnergyPlus-Support@g...





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