What distinctive feature is associated with air-impermeable insulation?

The distinctive feature associated with air-impermeable insulation is that it effectively prevents air movement altogether. This characteristic is crucial for maintaining energy efficiency within a building's envelope. By minimizing air infiltration and exfiltration, air-impermeable insulation helps to reduce the transfer of heat, thereby improving the building's thermal performance.

This insulation type functions by creating a barrier that air cannot easily pass through, which is fundamental for enhancing both comfort and energy savings. When installed properly, it aids in controlling indoor climate, preventing drafts, and maintaining a stable temperature, which is essential for efficient heating and cooling processes. Such properties make air-impermeable insulation particularly valuable in various building applications, especially in energy-efficient designs.

In contrast, allowing significant air movement or claiming that it is only usable in crawl spaces does not align with the definition of air-impermeable materials. Similarly, while thermal bridging is a concern in insulation practice, air-impermeable insulation itself does not create thermal bridges, as its primary purpose is to limit air flow rather than enhance heat transfer.