Demerara windows were built primarily into 18th- and 19th-century Colonial architecture-styled buildings to cool homes in hot climates, such as Guyana, before the invention of air conditioning. The window design includes perforated sides and louvres to block direct sunlight. They are shuttered sash windows with the shutter hinged at the top so it could be propped open, sloping outward. They were generally propped open with a stick. At the window sill, a container of ice, water, or a potted plant helps cool warm air as it passes through the window into the building. The windows are generally fitted in the upper floors. Initially, this type of window was just used in the homes of the wealthy, but spread over time to the homes of other classes of people.