In which type of space are ducts not required to be sealed?

Ducts in conditioned spaces are required to be sealed to ensure energy efficiency, control air leakage, and maintain indoor air quality. Conditioned spaces are those areas where heating, cooling, or humidity is actively managed to create a comfortable environment. Because these spaces are controlled and more sensitive to changes in airflow and temperature, sealing ducts prevents leaks that could degrade performance and increase energy costs.

In contrast, unconditioned spaces, natural spaces, or outdoor spaces do not have the same air quality or temperature control requirements. In unconditioned spaces, for instance, any air loss from ducts can be less critical as these spaces do not maintain a controlled environment, meaning that sealing may not be necessary. Similarly, in natural and outdoor spaces, ducts are often exposed to environmental factors, and sealing may not be feasible or necessary for performance. This distinction highlights the importance of sealing in conditioned spaces to achieve efficient and effective heating and cooling systems.