[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [EnergyPlus_Support] wall and roof color
hello
Regarding your first question, Color does have an effect but COLOR can be varied by changing the Emittance , absorptance of the material
For Example: If you want your walls to be black then
0.9000000 , !- Thermal Emittance
0.9500000 , !- Solar Absorptance
These values are function of color of material.
another example:
if you walls are white then
0.9000000 , !- Thermal Emittance
0.2600000 , !- Solar Absorptance
the values vary and you could look up them from any heat transfer book. The values i have written are at 30Deg C.
Again if you wall is made of say asphalt then the E+ material values will have the correct values of these fields to take into account the effect of color of asphalt.
So i can is that the software E+ is taking care of it, however feel free to cross check the values from any data book. The values vary with temperature, roughness which will be very difficult to quantize.
Regarding 2: a possbile reason for deviation from what you expect could be that in the materials you mentioned CONCRETE - 3/4 IN MORTAR, CEMENT SA 3 / 4 IN, A1 - 1 IN STUCCO
These values will very with color or your concrete/ material which may be a little darker, or lighter basically vary from place to place so you may feel these are not satisfing your requirements. Then again the Roughness of the materials are different .
Hope this helps
Thanks
Rahul Chillar
Building Systems lab
Graduate Research Assistant
Univ of Illinois Urbana Champaign
teklay Weldeabzgi <teklay1979@xxxxxxxxx> wrote:
hello ever body i need some help on these questions
1. how does E+ considers the effect of wall and roof
color in cooling load. i know that color has a
considerable effect on cooling load of a building but
i can't understand how to take this effect in E+.
2. i have some doubt with material properties given in
the dataset of E+. especially on the thermal
emittance, solar Absorptance, and Solar Absorptance.
for example if u see the following three materials i
think they sould have the same property but it differs
greatly.
MATERIAL:Regular,CONCRETE - 3/4 IN MORTAR, !-
Material Name
Rough, !- Roughness
1.0000000E-02, !- Thickness {m}
0.7200000 , !- Conductivity {w/m-K}
1858.140 , !- Density {kg/m3}
830.0000 , !- Specific Heat {J/kg-K}
0.9000000 , !- Thermal Emittance
0.2000000 , !- Solar Absorptance
0.2000000 ; !- Visible Absorptance
MATERIAL:Regular,PLASTER - CEMENT SA 3 / 4 IN, !-
Material Name
Smooth, !- Roughness
9.9999998E-03, !- Thickness {m}
0.7200000 , !- Conductivity {w/m-K}
1858.140 , !- Density {kg/m3}
830.0000 , !- Specific Heat {J/kg-K}
0.9000000 , !- Thermal Emittance
0.7800000 , !- Solar Absorptance
0.7800000 ; !- Visible Absorptance
MATERIAL:Regular,A1 - 1 IN STUCCO, !- Material Name
Smooth, !- Roughness
2.0000000E-02, !- Thickness {m}
0.6900000 , !- Conductivity {w/m-K}
1858.140 , !- Density {kg/m3}
830.0000 , !- Specific Heat {J/kg-K}
0.9000000 , !- Thermal Emittance
0.9200000 , !- Solar Absorptance
0.9200000 ; !- Visible Absorptance
MATERIAL:Regular,CONCRETE - 3 / 4 IN STUCCO, !-
Material Name
VeryRough, !- Roughness
9.9999998E-03, !- Thickness {m}
0.7100000 , !- Conductivity {w/m-K}
1874.160 , !- Density {kg/m3}
830.0000 , !- Specific Heat {J/kg-K}
0.9000000 , !- Thermal Emittance
0.7200000 , !- Solar Absorptance
0.7200000 ; !- Visible Absorptance
why is this happen ? if these properties are not the
exact value can u help me how to get the exact value.
you can imagin that these properties varies the
cooling load greatly.
tahnks
tek
__________________________________
Do you Yahoo!?
Yahoo! Mail is new and improved - Check it out!
http://promotions.yahoo.com/new_mail
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 SponsorADVERTISEMENT
---------------------------------
Yahoo! Groups Links
To visit your group on the web, go to:
http://groups.yahoo.com/group/EnergyPlus_Support/
To unsubscribe from this group, send an email to:
EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
Thanks
Rahul Chillar
Grad Student
Building Systems lab
Univ Of Illinois Urbana Champaign
---------------------------------
Do you Yahoo!?
Yahoo! Mail Address AutoComplete - You start. We finish.
[Non-text portions of this message have been removed]
------------------------ Yahoo! Groups Sponsor --------------------~-->
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!
http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/dkFolB/TM
--------------------------------------------------------------------~->
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
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/EnergyPlus_Support/
<*> To unsubscribe from this group, send an email to:
EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/