Home Depot Windows Autumn Glenn Phil Harris ME

Home Depot Windows Autumn Glenn Phil Harris ME 340 – Winter 2009

Introduction • Validate Home Depot Claims – Justification • Economic troubles lead people to look for ways to significantly save money • Sometimes advertising draws people to a product for only marginal benefits • Validate Calculator model they used

Home Depot Claim Single vs. Double 6500 Series Vinyl Window Premium Line with Argon gas • Calculator • • ** Percentages very similar**

Heat Transfer Problem • Analyze Single and Double Paned Windows, Compare • Analyze Single Pane Outside Inside T ∞ = 293 K hi = 100 W/m 2 K T ∞ = 273 K ho = 250 W/m 2 K – Forced Convection Inside and Outside Forced Convection – No Free Convection (Inside or Outside) – Radiation Forced Convection Wall to Window – Wall Inside to Window – Window to Wall – No Solar Radiation – Conduction through the window Window to Wall Conduction εwall =. 89 ε window =. 9

Heat Transfer Problem Outside • Analyze Double Pane – No Free Convection (Inside or Outside) – Radiation – – – T ∞ = 273 K ho = 250 W/m 2 K Forced Convection Argon k=. 0156 W/m 2 K Free Convection (based on single pane results 277. 8 – 276) T ∞ = 293 K hi = 100 W/m 2 K Forced Convection Wall Inside to Window to Wall Inside Pane 1 to Pane 2 to Pane 1 No Solar Radiation – Free convection inside the window – Forced Convection Inside and Outside – No Conduction Inside Wall to Window to Wall Pane 1 to Pane 2 to Pane 1 εwall =. 89 ε window =. 9

Results of Analysis • Single Pane – Heat Loss, q = 2, 361 Watts • Double Pane – Heat Loss, q = 807 Watts • Projected Savings of Double vs. Single – (807/2, 361) = 34. 2% • Error = Assumptions and Simplifications

Berkeley National Laboratory • Contributing Factors – House type • Single-story or Two-story Geographic location Orientation, Electricity and gas cost, Building configuration details (such as wall, floor, and HVAC system type) – Windows – – • Size • Shading • Thermal properties

Conclusion and Recommendations • Conclusion – Double pane are more energy efficient – Home Depot's results are reasonable – Accurate Calculator • Recommendations – High cost of more efficient windows may not be realized for years – Do research – Use the tools out there – Be an Engineer • Link To Calculator (Named “RESFEN”) http: //windows. lbl. gov/software/resfen/31/default. htm

Appendix Math. Cad Screen Shot