How does insulation work?
Insulation prevents the transfer of heat from warm to cool areas. Heat will always try to move from a warmer area to the cooler area. When it's hot outside you want to prevent the heat coming into the house. When it's cold outside, you want to keep the heat inside your house.
Heat moves between areas in three different ways:
- Radiation is transfer of heat through space, for example the warmth you feel standing in sunlight.
- Conduction is transfer of heat through an object, like the movement of heat through a metal frypan to the food.
- Convection is transfer of heat by the movement of a liquid or gas. Hot air rises and it will be warmer near the ceiling than the floor.
Different types of insulation work to prevent the different ways heat moves, and some combine multiple ways. The most common types of insulation, fibreglass batts, trap pockets of air which is a good insulator and prevents conduction of heat. Reflective insulation and sarking bounces radiative heat back in the opposite direction. A well sealed house, with seals around doors, windows and intrusions through the ceiling and walls like pipes and downlights, will prevent convection of heat.
