[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re:Re: [EnergyPlus_Support] A question about the center-of-glass conductance

Linda
 
Thank you very much for your  reply.
 
After reading your explanation, I fully understand the U value of the Window.
 
 
 

在2007-10-30，"Linda Lawrie" <linda@xxxxxxxxxx> 写道：


Actually, the output details and examples document is very clear.

For opaque surfaces, two conductances are 
calculated. Without and With film coefficients.

Field: Nominal U (w/o film coefs)

A nominal thermal conductance for the surface is 
calculated for the surface. It does not
include interior or exterior film coefficients as 
this is calculated during the simulation and is
dependent on several factors that may change 
during the simulation time period. Units for
this field are W/m2-K.

For windows, no value is reported because the 
film coefficients cannot be removed from the
U-value.

Field: Nominal U (with film coefs)
A nominal thermal conductance for the surface is 
calculated for the surface, including film
coefficients. Units for this field are W/m2-K.
<snip>
For windows, the "Nominal U with film coefs" is 
calculated using the following assumptions
from the WINDOW 4 program:
• Inside air temperature = 21.1 C (70 F)
• Outside air temperature = -17.8 C (0 F)
• Exterior film coefficient = 25.47 W/m2 (4.49 ft2-F-hr/BTU)
• Interior film coefficient = Calculated by EnergyPlus convection algorithm
• No incident solar beam radiation

To repeat, no value for without film coefficients 
is given because the U Factor for windows is not 
calculated without film coefficients. Only a 
value is shown for the conductance with film 
coefficients at the conditions stated in the last section.

Linda

EnergyPlus WebSite: http://www.energyplus.gov
Owner: EnergyPlus_Support list
Member: EnergyPlus Development Team

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]



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.pdf under the Documentation link and press the "search" button.
 
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    mailto:EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    mailto:EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> 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/