With the advent of increasingly more efficient light sources, interior lighting levels have continued to rise dramatically. However, in many cases these higher lighting levels caused more complaints than the previously lower lighting levels. This was because many of the lighting engineers who designed the newer lighting layouts ignored, or were ignorant of, many parameters that need to be considered other than illumination levels. A knowledgeable background in lighting fundamentals includes a thorough understanding of such topics as equivalent sphere illumination, visual comfort probability, daylighting, and controls.