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

 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
J.McHugh

 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
J.McHugh

 The energy that passes through is measured in
WATTS ( 1W = 1J/s )
 A U-value tells us how much energy passes through
1m 2 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/m 2 / °C
J.McHugh

 Different materials have different U-values
 Energy lost can be calculated as
E = U-value x area x temperature difference
( W/m 2 / °C ) (m 2 ) ( °C)
J.McHugh

 Old single glazed windows with a metal frame
 Typical U-value = 5.6
 Area = 1m 2
 Inside Temp. = 20 °C
 Outside Temp. = 10 °C
Calculate energy lost
J.McHugh

 Longman Worksheet
P1a.2f – Calculating Energy Losses [H]
J.McHugh

1.
Complete Keeping Warm worksheet
2.
Finish Calculating Energy Losses worksheet
DUE: Wednesday December 8 th
J.McHugh