1. U – Factor Calculator A theoretical Approach 6/19/20151Semester Project - Clark Davis

2. Window System Conduction 6/19/20152Semester Project - Clark Davis Natural Convection Conduction Cellular Convection Forced Convection Interior Exterior

3. U-Factor 6/19/2015Semester Project - Clark Davis3 U-factor (U-value). A measure of the rate of non-solar heat loss or gain through a material or assembly. It is expressed in units of Btu/hr-sq ft-°F (US) or W/sq m-°K (European metric). Values are normally given for NFRC/ASHRAE winter conditions of 0° F (18° C) outdoor temperature, 70° F (21° C) indoor temperature, 15 mph wind, and no solar load. The U-factor may be expressed for the glass alone or the entire window, which includes the effect of the frame and the spacer materials. The lower the U-factor, the greater a window's resistance to heat flow and the better its insulating value.

4. U-Factor Calculator Interface 6/19/2015Semester Project - Clark Davis4 Input Window Dimensions & Conditions Input Window Construction Solve for U-Factor Visual of Temperature Gradient

5. Results 6/19/2015Semester Project - Clark Davis5 Single Pane Double Pane Double Pane Argon Filled Theoretical = 0.188Theoretical = 0.181* Theoretical = 0.367* Theoretical = 0.188* *For a 1m*1m with 2 mm panes and 10 mm spacing and window at standard test conditions. U factor given in w/m^2.

6. Conclusion Results differ significantly from typical values – Modeling may use incorrect assumptions Advantages of double pane are significant – Approximately 100% increase Advantage of Argon is minimal – Approximately 5% increase 6/19/2015Semester Project - Clark Davis6

7. Sources Argon Properties – http://www.mhtl.uwaterloo.ca/old/onlinetools/air prop/airprop.html http://www.mhtl.uwaterloo.ca/old/onlinetools/air prop/airprop.html U-Factor Definitions – http://www.efficientwindows.org/glossary.cfm http://www.efficientwindows.org/glossary.cfm Typical Values of U-Factor – http://www.servicemagic.com/article.show.The-U- factor-of-Thermal-Replacement- Windows.8839.html http://www.servicemagic.com/article.show.The-U- factor-of-Thermal-Replacement- Windows.8839.html 6/19/2015Semester Project - Clark Davis7