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Re: [EnergyPlus_Support] Re: Zone Temperature Peaks too Early



There are several convection coefficient options as well as the potential for user generated coefficients that allow for curve objects that you might explore as well.  I find that the French thermal regulation of steady state 7.7 W/m2.k works well most of the time, and that FisherPedersenCeilingDiffuserWalls and FisherPedersenCeilingDiffuserCeiling are the most interesting. You can also set a schedule to modify the user value, then use EMS to change the schedule based on the temperature of your wall or some other variable. 

Surface Type AllInteriorWalls
Convection Coefficient 1 Location Inside
Convection Coefficient 1 Type Value
Convection Coefficient 1 7.7
Convection Coefficient 1 Schedule Name
Convection Coefficient 1 User Curve Name
Convection Coefficient 2 Location Inside
Convection Coefficient 2 Type
Convection Coefficient 2
Convection Coefficient 2 Schedule Name
Convection Coefficient 2 User Curve Name

Surface Type AllInteriorWalls
Convection Coefficient 1 Location Inside
Convection Coefficient 1 Type FisherPedersenCeilingDiffuserWalls
Convection Coefficient 1
Convection Coefficient 1 Schedule Name
Convection Coefficient 1 User Curve Name
Convection Coefficient 2 Location Inside
Convection Coefficient 2 Type
Convection Coefficient 2
Convection Coefficient 2 Schedule Name
Convection Coefficient 2 User Curve Name




Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
  





On Tue, May 7, 2013 at 3:02 PM, jeffreylauck <JeffLauck@xxxxxxxxx> wrote:
 

Jean,

Thanks for your response. I suppose it's possible that internal surfaces are slowing convection heat transfer in the actual house, but there's not a lot of furniture in the space. A small couch, a chair, and a table are about it.

The only way I can think of to test this theory is to increase the roughness of the internal surfaces in the zone. Do you have any other suggestions?

Thanks,

Jeff



--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@...> wrote:
>
> Could it be that the actual convection from surfaces is different or more or less than those modelled thereby transfering heat from surfaces to air faster or slower. Are there more internal surfaces like furniture which could contribute the these effects?
>
> Jean
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "jeffreylauck" <JeffLauck@> wrote:
> >
> > Hello All,
> >
> > First off, thanks for a great community. I've learned a lot from searching through the message archives over the past few months.
> >
> > I have a model of a Passive House that I am trying to validate using measured data from the actual house. I've created an hourly schedule file for the lights, electric equipment, window usage, blind usage, and hot water consumption based on sub-hourly data collected at the site. I'm using a custom weather file from the roof-top weather station that monitors dry bulb temp, relative humidity, wind speed and direction, and global horizontal solar radiation. The diffuse radiation component was estimated using the Erbs model prior to importing the data into the weather utility. Currently I'm only looking at the summer of 2012.
> >
> > The problem I'm having is that the peak temperatures in the model occur 2-4 hours before the measured data (2-3 hours in July and September, 3-4 hours in August). Here's what I've determined so far:
> >
> > 1. It's not due to a time shift in the data. I've verified that all data is GMT-8 and that no Daylight Savings flags are included in the IDF.
> > 2. It's not due to a lack of thermal mass. I added a bunch of internal mass as a test and the peaks were reduced but occurred at the same time as previous models. Also, I'm using CondFD with 9 nodes and a 1-minute timestep.
> > 3. I don't think it's due to my custom weather file, as I get a similar results using TMY data.
> >
> > Does anyone have any suggestions on where to look next? Any ideas would be greatly appreciated.
> >
> > Thanks,
> >
> > Jeff
> >
>




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