Which of the following is typically considered undesirable in building design?

In building design, air infiltration is typically considered undesirable because it leads to uncontrolled air leaks that can negatively impact a building's energy efficiency and indoor air quality. When air infiltrates a building without proper management, it can result in higher heating and cooling costs as it compromises the effectiveness of the thermal insulation. This unregulated airflow can cause discomfort by allowing drafts in and leading to temperature fluctuations within the building. Additionally, excessive air infiltration can introduce outdoor pollutants and allergens into the indoor environment, affecting overall occupant health.

On the other hand, thermal insulation, natural lighting, and effective ventilation are all essential elements in building design that contribute positively to energy conservation, occupant comfort, and overall well-being. Thermal insulation helps retain heat in the winter and keeps buildings cool in the summer, while natural lighting promotes a pleasant atmosphere and can reduce dependence on artificial lighting. Effective ventilation is crucial for maintaining good air quality and regulating indoor temperatures. Thus, air infiltration stands out as the only factor that is generally regarded as undesirable in the context of building design.