Re: [EnergyPlus_Support] High Mean Air Temperature in Winter

[wah <wong@xxxxxxxxxxxxxxxxxxxxxxxxx>]

Dear Mike,

Thank you for the reply.

I could not understand the meaning of: 
"the position of the living space is shifted from the other zone 
as seen in the dxf output file"
As I do not have the software to view the drawing file, 
could you please take a look of the building structure I have uploaded?

What should the value of floor's view factor to ground be?
The value of 0 and 1 both give an error of:
Floor Tilt=0.0, much less than expected tilt of 180, for Surface=FLOOR: LIVING, in Zone=LIVING ZONE

About the high MAT in Winter,
I made a comparison with another simulation software,
with the same building construction and weather data,
the MAT came out in a totally different trend
(comparison graph in the same file)
Although the other simulation programme uses Resistance Network Solution,
I suppose the results would not differ to such an extent..

The file is uploaded as HighMeanAirTemperatureInWinter2

Please advice and thank you!

PuiWah






こんにちは。

In message "Re: [EnergyPlus_Support] High Mean Air Temperature in Winter",
Michael J. Witte wrote...
 >My apologies for the delayed response.
 >
 >The reporting for solar gains is somewhat confusing, because some of the 
 >variables are W/m2, and some are W.
 >
 >  Environment:Diffuse Solar [W/m2]
 >  Environment:Direct Solar [W/m2]
 >  Zone Transmitted Solar[W]
 >
 >Dividing Zone Transmitted Solar[W] by the total window are of the zone gives 
 >numbers which are smaller than the sum of environment diffuse and direct.
 >
 >These results look quite reasonable to me.  The south wall is mostly glass with 
 >overhangs, and the sun is low in January, so the solar gains through the south 
 >windows in January will actually be greater than in July.  This is a small 
 >zone, and the outdoor temperatures are 0 to 13C, so I would expect the solar 
 >gains to quickly warm the space during the daytime.
 >
 >I noticed that the position of the living space is shifted from the other zone 
 >as seen in the dxf output file.  You may want to check the geometry inputs.
 >
 >Mike
 >
 >
 >On 24 Oct 2005, at 13:40, 黄佩華 wrote:
 >
 >> Hello.
 >> 
 >> I am trying to model the Living zone of a single storey residential 
 >> building. It is a 5m(X) x 3.6m(Y) x 3.75m(Z) space, with 6.8m2 South 
 >> Window and 1.2m2 West Window, without space heat gain, purchased air 
 >> heating and cooling.
 >> Weather data used is JAPAN_Osaka_IWEC.epw. 
 >> 
 >> During Winter, the Living Zone MAT gets so high (i.e. 2,4,7,9,10 Jan 
 >> above 30C; 5,6,8 Jan above 25C) that purchased air heating does not 
 >> need to function. As the MAT for Summer during period without cooling 
 >> is around 35C, I wonder how the Winter MAT becomes so high. 
 >> 
 >> A rough comparison of Zone Transmitted Solar shows it is at least 2 or 
 >> 3 times the sum of Direct and Diffuse Solar in Winter, but about the 
 >> same with sum of Direct and Diffuse Solar in Summer. I could not find 
 >> the explanation of how Solar Radiation Transmission through Windows is 
 >> calculated in the Engineering Doc thus just comparing directly though 
 >> they are of different units.
 >> 
 >> I have uploaded the idf file: HighMeanAirTempInWinter.
 >> 
 >> Please advice.
 >> 
 >> Thank you.
 >> 
 >> Wah
 >> 
 >> 
 >> 
 >> 
 >> 
 >> 
 >> 
 >> 
 >> 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.
 >> 
 >> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press the
 >> "search" button.
 >> 
 >> Yahoo! Groups Links
 >> 
 >> 
 >> 
 >> 
 >> 
 >> 
 >> 
 >> 
 >
 >
 >
 >========================================================
 >Michael J. Witte, GARD Analytics, Inc.
 >EnergyPlus Testing and Support      
 >EnergyPlus-Support@xxxxxxxx
 >
 >
 >




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