1. P1 – AQA 2011 P1.1. The Transfer of Energy Mr. J. McHugh
U - values
P1 – AQA 2011
P1.1. The Transfer of Energy
Mr. J. McHugh
J.McHugh

2. Learning Objectives To state what U-values are
Evaluate the effectiveness of different types of material used for insulation, including U-values and economic factors including payback time
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3. What IS a U-value?
Used in Europe to help architects choose building materials
Tells us how well heat passes through a material
The lower the U-value, the less heat passes through
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4. What does it mean?
The energy that passes through is measured in WATTS ( 1W = 1J/s )
A U-value tells us how much energy passes through 1m2 of a material with a particular thickness
The standard U-value looks at the energy transferred (W) where there is a 1°C temperature difference between the two sides of material
Thus, the unit for a U-value is W/m2/°C
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5. Using U-values Different materials have different U-values
Energy lost can be calculated as
E = U-value x area x temperature difference
( W/m2/°C ) (m2) (°C)
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6. Old Single Glazing Old single glazed windows with a metal frame
Typical U-value = 5.6
Area = 1m2
Inside Temp. = 20°C
Outside Temp. = 10°C
Calculate energy lost
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7. Class Task Longman Worksheet P1a.2f – Calculating Energy Losses [H]
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8. Homework Complete Keeping Warm worksheet
Finish Calculating Energy Losses worksheet
DUE: Wednesday December 8th
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