P1 – AQA 2011

P1.1. The Transfer of Energy

Mr. J. McHughJ.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

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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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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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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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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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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

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