33. Heat loss from a house

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How to reduce heat loss from your house (and save on your heating bills!)

There are several things you can do to reduce the heat loss from your house and therefore reduce your fuel bills.

Firstly we can install double glazed windows. Double glazing has two panes of glass with an air gap in the middle. Air is a very poor conductor and so this 'air sandwich' reduces heat loss by conduction. Triple glazing is also now widely used for even better insulation (a sort of 'air club sandwich').

In the roof space you can install fibre glass loft insulation (or mineral rock wool) which contains a lot of air pockets. This helps to reduce heat transfer because... (yes, you guessed it) air is a very poor conductor of heat.

Usually houses are built with two 'skins' of bricks. The cavity between each of the skins contains air which does a fair job of reducing heat loss from the house. However, we can reduce heat loss even more by filling the cavity with insulation such as mineral rock wool or expanded polystrene beads. This is called 'cavity wall insulation' and it reduces heat transfer by trapping pockets of air so that warm air cannot rise by convection.

A simple way to reduce heat loss by convection is to use draft excluders for gaps around the windows and doors. This method has one of the fastest 'payback times' because it usually doesn't cost much to install in the first place.

Finally, you can place reflective metal foil behind radiators. This helps to reflect infra-red heat radiation from the hot radiator back into the house.

GCSE Physics Keywords: Heat transfer, loft insulation, cavity wall insulation, trapped air, conduction, convection, radiation, heating costs

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