What mechanism does rigid board insulation use to reduce heat transfer?

Rigid board insulation utilizes air spaces or cells as its primary mechanism for reducing heat transfer. This is based on the principle that air is a poor conductor of heat. The structure of rigid board insulation typically includes numerous tiny air pockets or cells that trap air. These trapped air pockets inhibit the movement of heat, thus minimizing thermal conductivity.

The effectiveness of rigid board insulation in managing heat transfer makes it valuable in various applications, including roofing systems. By maintaining a cooler indoor environment in summer and preventing heat loss in winter, this insulation plays a crucial role in energy efficiency.

Other choices do not accurately represent how rigid board insulation works. Reflective surfaces might enhance thermal performance, but they are not the primary mechanism at play here. Solid foam is indeed part of some rigid board insulations but does not independently account for heat transfer reduction without the inclusion of air spaces. Metal barrier systems are used for specific purposes, such as vapor barriers, rather than for the fundamental insulation performance that air spaces provide.