The purpose of a bay window is to admit more light than would a window flush with the wall line. A bay window may be rectangular, polygonal, or arc-shaped. ... A bay window is also called an oriel, or oriel window, when it projects from an upper story and is supported by corbels.

Why are bay windows so popular?

During the English Renaissance (15th – 17th century) sash bay windows became popular in domestic architecture. Many of the grand houses of the Baroque period (16th – 18th century) favoured sash bay windows for their capacity to bring light into a building thus illuminating the ornate detailing of the time.

Why are bay windows bad?

It may increase solar heat gain, and it will certainly increase light levels when the sun comes up, which could be a problem if you like your rooms dark when you're sleeping. The addition of window dressings may be a tad more expensive than usual as the angles may present installation issues.