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Loss of heat

This is why sport clothes are usually white and houses are white
in hot countries
Our houses lose heat energy by all three methods
This is both uneconomical and ungreen

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Heat loss can be avoided by

Loft insulin
Carpets and curtains
Double glazing
Cavity wall insulation
Draught proofing
Lagging of hot water tanks and pipes
Energy efficiency

The efficiency of a machine can be calculated using the

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For % efficiency, multiply answer by 100

Example of efficiency = useful energy input
energy input

How efficient is a hairdryer that uses 15 watts of power but
produces only 5 watts of useful energy

Efficiency = 5 = 0.33 = 33 %


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