Re: [EnergyPlus_Support] Surface outside temperature (Roof)

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

Two other significant factors are thermal absorptance (emissivity) and the 
exterior convection coefficient which is driven primarily by wind speed.  And, 
of course, the thermal conductivity of the other layers in the roof 
construction, the outdoor air temperauture and the temperature of the thermal 
zone on the inside of the roof.  73C is not unreasonable on a hot sunny day.

Mike


On 10 Jun 2006 at 17:47, chunming wrote:

> Hello,
> 
> The surface outside temperature of a building roof at noon goes to 73 
> degree.
> I wonder if it is reasonable or not.
> The direct solar at noon (10:00-14:00) is about 760-860 W/m2.
> And below lists the setting of outside layer of the roof in my simulation.
> 
> MATERIAL:REGULAR,
>     R006-1,                  !- Name
>     Rough,                   !- Roughness
>     .1,                      !- Thickness {m}
>     .17,                     !- Conductivity {W/m-K}
>     600,                     !- Density {kg/m3}
>     1600,                    !- Specific Heat {J/kg-K}
>     0.9,                     !- Absorptance:Thermal
>     .8,                      !- Absorptance:Solar
>     0.7;                     !- Absorptance:Visible
> 
> Two main factors, conductivity and absorptance solar,  will affect the 
> surafce outside temperature.
> Is there any other factor I have to take care or deal with?
> Thank you very much.
> 
> Chunming
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx





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