What issue can broken seals on double-paned windows cause?

Broken seals on double-paned windows primarily lead to issues with insulation and energy efficiency. When the seal between the panes fails, it allows moisture and air to enter the space between the glass, which can result in condensation and possibly lead to fungal growth if the moisture remains trapped.

The presence of moisture can create an environment conducive to mold and mildew, which can pose health risks and degrade indoor air quality. Therefore, the correct answer highlights the potential for fungal growth as a consequence of broken seals in double-paned windows.

Other choices focus on different aspects that do not directly relate to the primary issue of broken seals. For example, improved heat resistance would not be a result of a broken seal, as the insulation properties would typically decrease rather than improve. Similarly, reduced energy transmission does not accurately define what happens; while energy efficiency does decrease due to the compromised insulation, the main issue of concern is moisture ingress and its subsequent effects. Cracked glass panes may occur due to other physical impacts or stresses but are not a direct result of seal failure.