Hi, Xing
0.272 W/m2-K U-value is only a guide for minimum requirement.
The film is required to prevent moisture condensation on the insulating material.
I think, this U value is equivalent to R4. The current minimum for Toronto is R8. The usual value used is R12, The ceiling is R20 and above. A two storey residential house with a basement, and with these insulation hardly need any heating in Winter.
When you use the R-value, the resultant is simply added together.
When you use U-value, it will be 1/(1/U1 + 1/U2). Therefore, the one with large U-value can be ignored.
You need to consider the thickness of the material as well to make the calculation for the resultant U-value, using the conductance value.
In EPlus material, I think the value of conductance is given. The material with a low conductance is a better heat insulator
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: xing.shi.2006@xxxxxxxxx
Date: Mon, 15 Aug 2011 11:44:33 +0000
Subject: [EnergyPlus_Support] ASHRAE 90.1 U-factor with or without surface film
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
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 currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
![]()
__,_._,___
0.272 W/m2-K U-value is only a guide for minimum requirement.
The film is required to prevent moisture condensation on the insulating material.
I think, this U value is equivalent to R4. The current minimum for Toronto is R8. The usual value used is R12, The ceiling is R20 and above. A two storey residential house with a basement, and with these insulation hardly need any heating in Winter.
When you use the R-value, the resultant is simply added together.
When you use U-value, it will be 1/(1/U1 + 1/U2). Therefore, the one with large U-value can be ignored.
You need to consider the thickness of the material as well to make the calculation for the resultant U-value, using the conductance value.
In EPlus material, I think the value of conductance is given. The material with a low conductance is a better heat insulator
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: xing.shi.2006@xxxxxxxxx
Date: Mon, 15 Aug 2011 11:44:33 +0000
Subject: [EnergyPlus_Support] ASHRAE 90.1 U-factor with or without surface film
ASHRAE 90.1-2007 Table 5.5-3 require that U-value of exterior wall shall be 0.272 W/m2-K. E+ provides U-values with and without film. Which one should match 0.272? We think it should be the U-value without film. Are we right?
Thanks!
Thanks!
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
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 currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___