What does the still air inside insulation primarily help reduce?

The still air inside insulation is effective at reducing convection. Convection is the process of heat transfer that occurs through the movement of fluids, which includes liquids and gases. In the context of insulation, the presence of still air helps to prevent air movement within the insulation material. When air is still, it doesn't carry heat away from a warm area to a cooler area, thereby minimizing heat loss or gain through convection.

By trapping air molecules that do not easily move, the thermal resistance of the insulation is increased, which is crucial for maintaining a building's energy efficiency. This characteristic of insulation is particularly important in attics, where heat can escape or enter through the ceiling, significantly affecting the overall temperature regulation of the home.

In contrast, conduction refers to heat transfer through solid materials, and radiation pertains to heat transfer through electromagnetic waves. Evaporation relates to phase changes in water, which is not directly linked to insulation properties. The primary role of insulation is to impede convection by utilizing the still air that it holds, making it essential for effective thermal management.