What aspect of passive solar construction is most likely to have an impact on radon entry?

The design of the foundation plays a crucial role in influencing radon entry into a building. Radon is a naturally occurring radioactive gas that emanates from the decay of uranium in soil and rock, and it can enter buildings through various pathways, particularly through the ground. A well-designed foundation can minimize the potential for radon infiltration.

For instance, a foundation that is properly sealed and constructed using materials that prevent soil gas intrusion can significantly reduce radon levels within the building. Techniques such as reinforced concrete slabs, which are built to create a barrier against ground gases, or advanced designs that include passive ventilation systems, are integral in minimizing radon entry.

In contrast, window orientation, insulation type, and the presence of a basement can influence energy efficiency and temperature regulation but have a lesser direct effect on radon levels compared to how the foundation interacts with the ground below. For example, while a basement might increase the likelihood of radon being present due to its proximity to the soil, the actual construction and sealing of the foundation itself are what primarily determine the level of protection against radon infiltration.