Posted in Physics Revision

Heating Buildings and Home Insulation

P1 1.6

Insulator Definition: a thermal insulator acts as a barrier to the transfer of energy by heating.

Heating a house costs money. However, a lot of the energy we pay for is lost to the surroundings. So insulating a house can save money as less heat energy leaves the house.

Things we can do to improve how insulated our houses are include:

  • double- or triple-glazed windows → there is air (or sometimes argon) in between the sheets of glass; gasses are poor conductors, so less heat is lost.
  • cavities in walls → again, a layer of air is between the walls, preventing heat loss by conduction.
  • polystyrene foam insulation → polystyrene is an excellent insulator.
  • reflective surface behind radiators → reflects heat back into house and away from walls.
  • draught excluders → stop cold air getting in and hot air getting out.


This shows how goodmaterial or building component is as an insulator.

The lower the U-Value, the less energy the material transfers, and so the better an insulator it is. So, when insulating homes, we look for materials with LOW U-VALUES.

(It’s unit is W/m²°C, but I don’t think you need to know that.)


The components we use to insulate our homes also cost money. To work out if a method of insulation is cost effective, we look at the payback time.

This is the length of time it takes to save the amount of money that the improvement cost.

E.g. if insulating a hot water tank cost £60 and it saves £15 a year, then the payback time is 60 divided by 15, which equals 4.

The shorter the payback time, the more cost effective the insulation method is.


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