What are general performance requirements of windows?

The general performance requirements of windows encompass various factors critical to both building energy efficiency and occupant comfort. Option B, which focuses on limiting air leakage, is indeed an essential performance requirement. Reducing air leakage through windows contributes to improved indoor air quality, enhances thermal comfort, and increases the overall energy efficiency of a building by minimizing the unwanted transfer of conditioned air to the outside.

Although minimizing heat loss (option A) is also an important factor that impacts the overall efficiency of windows, focusing solely on air leakage captures a specific and vital aspect of window performance. While window aesthetics (option C) can play a role in design considerations, they are not considered a general performance requirement from an energy efficiency or building code perspective.

The comprehensive option that encapsulates all these aspects would be the most representative. Therefore, acknowledging that limiting air leakage (which is a critical function of a window) is sufficient underlines the importance of recognizing it as a performance requirement, but it does not negate that heat loss mitigation and aesthetic value can also contribute to the overall performance of windows in a building envelope.