Re: [EnergyPlus_Support] High Mean Air Temperature in Winter

["Michael J. Witte" <mjwitte@xxxxxxxx>]

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, ?©?Î?Ø 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
> 
> 
> 
> 
> 
> 
> 
> 
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> 
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> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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