Casement Window Casement windows are a popular choice for many homeowners due to their many advantages. They offer full opening, allowing for maximum ventilation and airflow into your home. They work well when combined as part of a larger window installation, such as in bay, bow, or French windows.Casement windows are one of the most energy-efficient windows. The sash creates an airtight seal against the window frame when closed making it hard for air to get through. | ![]() |