For reflecting insulation to perform optimally, what is essential regarding its exposure?

For reflecting insulation to perform optimally, it is crucial that it must be exposed to an air space. This is because reflecting insulation works by utilizing surfaces that reflect radiant heat rather than absorb it. When there is an air space adjacent to the reflective surface, it allows for effective thermal performance, as the air acts as an insulator, preventing heat transfer through conduction.

The presence of air space enhances the reflective properties of the insulation by minimizing the amount of radiant heat that can enter or escape, thus improving energy efficiency in buildings. Without this air space, the efficiency of the radiant barrier can be significantly diminished, as it would not be situated in an optimal condition to perform its intended function of thermal resistance.