September 3, 2011

4.8 Insulation

Describe how insulation is used to reduce energy transfers from buildings and the human body.

Insulation is used in housing to trap heat inside the house and keep the house warm (or in warmer countries like Thailand, the insulation is used to stop the heat from getting into the house, not to stop the cold getting out, there is a difference!)

The walls of houses are filled with ‘Insulation’ to stop heat escaping; this insulation is made of a material that is a very poor conductor (often fibreglass) in some cases this fibreglass is then coated in a silver material that reflects the infra-red radiation.

This means that both the relevant types of heat are being reduced; Conduction is reduced by a poor conductor and Radiation is stopped by something that reflects the heat. And convection isn’t really a problem in houses as convection can’t pass through the solid doors and walls of a house.

The same principles work for the human body… or anything for that matter, If you want to stay cool wear something white as it will reflect a large amount of the radiation. On the other hand if you want to stay warm, it is also a good idea to wear white, this is because if you were to wear a dark colour it would absorb the heat from your body and then radiate it out into the atmosphere which is not going to keep you cool.

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