What is the effect of an air gap in insulation?

An air gap in insulation can significantly impact the thermal performance, often rendering it much less effective. Insulation works by reducing heat transfer, and when there is an air gap present, it can allow air movement that disrupts this ability. If the air gap is not part of a properly designed assembly, it can lead to increased heat loss or gain, depending on the environment.

In some cases, if insulation is improperly installed or an air gap exists due to movement or settling, it can create a scenario where the insulating material does not perform as intended, effectively diminishing its insulating properties at that specific point. The gap can allow insidious convection currents that bypass the insulation, undermining the thermal barrier it is supposed to provide.

While the other options present different interpretations of air gaps in insulation, they do not accurately capture the broader implications of introducing an air gap within insulation. The presence of this gap generally leads to a situation where the insulation does not serve its purpose effectively, which is why considering air gaps in insulation design is crucial for maintaining desired energy efficiency and thermal performance.