Daylighting and Human Performance PDF

Daylighting is the practice of using natural light to provide illumination in interior environments. Fifty years ago, practically all schools and workplaces used daylight as the primary illumination source. With the advent of inexpensive electricity and widespread use of fluorescent lighting in the 1950s and 1960s, states began to abandon requirements for minimum daylight illumination in their building codes. As energy costs soared, starting with the energy crises of the 1970s, the glazed areas of buildings came to be regarded by many as an energy liability, seen as increasing heating and cooling loads. Since cooling loads typically dominate in non-residential buildings, solar gain through windows became a driving concern.