hourly, daily, and seasonal, temperature-and-daylight variations. If the temperature is correct, and a room is unoccupied, the drapes can automatically close to reduce heat transfer in either direction. To help distribute sun room daylight to the sides of rooms that are farthest from the equator, inexpensive ceiling-to-floor mirrors can be used. Building codes require a second means of egress, in case of fire. Most designers use a door on one side of bedrooms, and an outside window, but west-side windows provide very-poor summer thermal performance. Instead of a west-facing window, designers use an R-13 foam-filled solid energy-efficient exterior door. It may have a glass storm door on the outside so that light can pass through when the inner door is opened. East/west glass doors and windows should be fully shaded top-to-bottom or a spectrally selective coating can be used to reduce solar gain. Design Architects and interior designers often use daylighting as a design element. Good daylighting requires attention to both qualitative and quantitative aspects of design. Qualitative Utilizing natural light is one of the design aspects in architecture; In 1929, the French architect, Le Corbusier said that "The history of architectural material... has been the endless struggle for light... in other words, the history of windows." As he emphasized in his architecture (such as Notre Dame du Haut), daylighting has been a major architectural design element (See MIT Chapel and Church of the Light for examples). Not only the aesthetic aspects, the impact of daylighting on human health and work performance is also considered as qualitative daylighting. The current studies show that lighting conditions in workplaces contribute to a variety of factors related to work satisfaction, productivity and well-being and significantly higher visual acceptance scores under daylighting than electrical lighting. Studies have also shown that light has a direct effect on human health because of the way it influences the circadian rhythms. Quantitative A well daylit space needs both adequate lighting levels and light that is well distributed. In the current building industry, daylighting is considered a building performance measure in green building certification programs such as LEED. Illuminating Engineering Society (IES) and the society of Light and Lighting (SLL) provide illuminance recommendation for each space type. How much daylighting contributes to the recommended lighting level determines daylighting performance of a building. There are two metrics that IES has approved to evaluate daylighting performance: Spatial Daylight Autonomy(sDA) and Annual