What are two factors that can negatively affect the performance of a ventilation system?

The correct response identifies that missing or damaged ventilation significantly impacts a ventilation system's effectiveness. Proper ventilation is crucial for maintaining air quality, controlling humidity, and ensuring that fresh air circulates throughout the building. If a ventilation system is compromised due to missing components or physical damage, it can lead to inadequate air exchange, stale air accumulation, and increased humidity levels, which can all contribute to comfort and health issues within the indoor environment.

In contrast, excessive insulation or the presence of too many windows can influence energy efficiency but does not directly relate to the performance of the ventilation system itself. High humidity and temperature variations may affect occupant comfort but do not inherently compromise the functionality of the ventilation system as much as the structural integrity of the system highlighted in the correct answer. Lastly, while too much airflow or continuous operation could theoretically present challenges, a well-designed ventilation system should be capable of handling the airflow requirements without issue. Therefore, missing or damaged components directly impairment system performance, making it the most relevant factor in this context.