Insulation Primer

Insulation is a material designed to slow down the flow of heat. In most North American regions, the primary function of insulation in the building envelope is to keep heat in, but insulation also plays an important role in keeping unwanted heat out in warmer months. Most insulation materials are lightweight fibrous or cellular materials that enclose air or gas pockets. Heat flows through these materials through conduction, convection, and radiation:

  • Conduction occurs through both the gas and the solid material that separates pockets of gas. Insulation is most effective at stopping conduction.
  • Convection occurs as air circulates through the insulation material and is usually a minor component.
  • Radiation occurs across air pockets in insulation or through air gaps in the building's shell.
Measuring Insulation Effectiveness
How to Verify Proper Insulation Levels