Insulation works by reducing the transfer of heat between two spaces. It does this by slowing down the movement of heat energy through conduction, convection, and radiation.
1. Conduction
Heat transfer through direct contact between materials with different temperatures. When placed between two materials with different temperatures, insulation reduces the rate at which heat is transferred through conduction.
2. Convection
Heat transfer through the movement of fluids or gases. Insulation materials create pockets of trapped air or gas within their structure. Since air is a poor conductor of heat, these pockets help to reduce convective heat transfer.
3. Radiation
Reflective insulation, such as foil-faced insulation, reflects radiant heat away from the surface. This helps to prevent heat gain in hot climates or retain heat in cold climates by reflecting the radiant energy towards its source.