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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 - PowerPoint PPT Presentation
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Home Depot Windows
Autumn GlennPhil 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
– Forced Convection Inside and Outside
– No Free Convection (Inside or Outside)
– Radiation – Wall Inside to Window– Window to Wall– No Solar Radiation
– Conduction through the window
Outside Inside
T ∞ = 273 K ho = 250 W/m2K
T ∞ = 293 Khi = 100 W/m2K
Forced Convection Forced Convection
Conduction
Wall to Window
Window to Wall
εwall = .89 ε window = .9
Heat Transfer Problem• Analyze Double Pane
– No Free Convection (Inside or Outside)
– Radiation – Wall Inside to Window– Window to Wall Inside– Pane 1 to Pane 2– Pane 2 to Pane 1– No Solar Radiation
– Free convection inside the window
– Forced Convection Inside and Outside
– No Conduction (based on single pane results 277.8 – 276)
Argonk=.0156W/m2K
εwall = .89 ε window = .9
Inside
T ∞ = 293 Khi = 100 W/m2K
Forced Convection
Wall to Window
Window to Wall
Outside
T ∞ = 273 K ho = 250 W/m2K
Forced Convection
Free Convection
Pane 1 to Pane 2
Pane 2 to Pane 1
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
AppendixMathCad Screen Shot