It has become very important for architects to understand how to choose a sustainable window and window frame system that will promote comfort, energy efficiency, durability, and longevity through quality construction. This unit describes how windows help promote healthy living conditions by increasing natural light available in the home and by helping to improve indoor air quality through natural ventilation. The second section describes how building products and materials should also be adaptable to the changing aesthetics of home design. Building form and energy efficiency are addressed in the third section. An overview of ENERGY STARr rated windows and how they can contribute to the LEEDr for Homes rating system end the program.