Which of the following describes a benefit of maintaining airtightness in buildings?

Maintaining airtightness in buildings significantly contributes to improved indoor air quality, which is a primary benefit. An airtight building effectively minimizes uncontrolled air leakage, allowing for better management of indoor environments. By controlling ventilation more efficiently, it becomes easier to implement effective air filtration systems that can remove pollutants, allergens, and moisture from the indoor air. This results in a healthier living or working space for occupants, as it reduces the risk of respiratory issues, mold growth, and the presence of indoor contaminants.

In contrast, the remaining options highlight scenarios that would typically be undesirable outcomes. Increased greenhouse gas emissions and higher heating costs generally stem from inefficiencies and higher energy consumption associated with poorly sealed buildings. Similarly, decreased property value is often linked to factors like poor insulation and insufficient energy efficiency, which are exacerbated by air leakage. Thus, the focus on airtightness stands out as contributing significantly to the health and comfort of building occupants.