The importance of Attic Insulation

Energy loss from a home is inevitable. The forces of equilibrium, the physics of nature, continually strive to balance the heat energy on the inside, with that on the outside. Even in the best built houses, when the heating or cooling system goes OFF, the inside and outside temperatures immediately begin to equalize. Attic insulation helps to make energy loss from a home as slow as possible, to minimize the amount of time the heating or cooling system must be on to keep the temperature within a comfortable range. To help achieve this objective, attic insulation is used to control convection.

CONVECTION

One of the most effective ways to increase thermal efficiency is to minimize convection by keeping cold air "out of circulation". The focus is on convection as it relates to attic insulation, particularly blown attic insulation (blown wool). The principles of convection are important to understand both to minimize its undesirable effects, and also to better explain preventative measures. Convection is the transfer of heat via the movement of air. Hot air is less dense than cold air, so it tends to rise; the denser cold air tends to sink. In winter, currents of hot air rising and cold air sinking, are created within the home by the heating system (hot air rising), and by heat loss through conduction and air infiltration (cold air sinking).

The better a home is insulated and the more effectively air infiltration is controlled, the less convection there is inside the house. The interior air is allowed to approach a state of equilibrium, and the temperature within the home remains more uniform.