What is the minimum total area of window glass in a room as a percentage of the floor area?

In building design, the recommended minimum total area of window glass in a room is traditionally considered to be 10% of the floor area. This guideline ensures that spaces receive adequate natural light and ventilation, which are important for creating a comfortable and healthy indoor environment.

The rationale behind establishing 10% as the minimum area is based on the average amount of daylight needed to illuminate a room sufficiently without relying solely on artificial lighting during the day. This percentage has been adopted in various building codes and standards to promote energy efficiency and occupant well-being.

In contrast, percentages lower than 10% may not provide enough natural light, which could lead to a dim and uninviting atmosphere. Higher percentages might be unnecessary or impractical in certain situations, resulting in higher construction costs without significant benefits. Therefore, the selection of 10% reflects a balance between adequacy of natural light and cost-effectiveness in building design.