Reducing unwanted energy transfers

• 4 methods of reducing heat loss

  Make walls from a material with low thermal conductivity

  Use cavity walls

  Use double glazed windows

  Insulate walls and attic
• Purpose of putting insulation in the gap in cavity walls

  To minimise air convection currents
• How does the gap in a cavity walls help reduce heat loss

  Heat cannot be conducted across the gap as the gap contains mostly air which does not conduct heat
• Double glazed window

  They have two panes of glass with a small air gap between them
• Benefit of double glazed windows

  Air gap between two panes minimise heat loss by conduction
• Friction

  Resistance an object encountered when moving over a solid or moving through a liquid