Transcript U-values 2028KB - Montgomery High School

P1 – AQA 2011
P1.1. The Transfer of Energy
Mr. J. McHugh
J.McHugh
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
J.McHugh
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
J.McHugh
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
J.McHugh
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)
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(°C)
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
J.McHugh
Class Task
Longman Worksheet
P1a.2f – Calculating Energy Losses [H]

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Homework
1.
Complete Keeping Warm worksheet
2.
Finish Calculating Energy Losses
worksheet
DUE: Wednesday December 8th
J.McHugh