These data represent the second floor of a 4-story atrium design. It is clear from the illumination plot that the atrium design still does not provide significant horizontal daylight illumination to much of the floor plate. However, the rendering and the false color luminance image (top right) reveal that the surface brightness of atrium walls increases the perception of brightness within the space and helps to balance the brightness from the perimeter windows. The floor area above 300 lux is 57% as provided primarily by the perimeter windows. Note however that some functional illumination reaches the second floor, and that the 3rd and 4th floor benefit even more significantly in this regard.

These data represent the second floor of a 4-story atrium design. The floor plate is very deep (80’) and the atrium is narrow by comparison (20’). With an 80’ floor plate depth and normal ceiling height, there is no atrium design that functionally daylight the space. It is clear from the illumination plot that the atrium design does not provide functional illumination to the floor plate. The false color luminance image (top right) reveals that the surface brightness of atrium walls are brighter than the surfaces within the space, however due to the great depth of the floor plate, this is of little benefit. The floor area above 300 lux is just 23% and is provided almost exclusively by the perimeter windows.

These data represent the second floor of a 4-story atrium design and is exactly like the previous case except with 10% SFAR translucent (light diffusing) skylights with a 50% visible light transmission (Tvis) added. The floor plate is still very deep (65’) and the atrium is wider but still too narrow (35’). With a 65’ floor plate depth and normal ceiling height, there is no atrium design that functionally daylight the space. It is clear from the illumination plot that the atrium design does not provide functional illumination to much of the floor plate. The false color luminance image (top right) reveals that the surface brightness of atrium walls are brighter than the surfaces within the space, however due to the depth of the floor plate, this is of modest benefit. The floor area above 300 lux increases from 29% with without the skylights to 31% with 10% SFAR. This modest increase does not warrant the introduction of skylights, however that design decision cannot simply be made depending on the performance of the second floor.

These data represent the second floor of a 4-story atrium design and is exactly like the previous case except with 10% SFAR skylights added. The floor plates are 50’ deep and atrium is the same width. This design represents a substantial commitment to daylighting by creating such a large atrium. This design meets the rule of thumb discussed in the ‘Overview’ above. However, with 50’ deep floor plates, minimal daylight reaches the center of the floor plate.. It is clear from the illumination plot that the atrium design does provide some functional illumination to the work plane. The false color luminance image (top right) reveals that the surface brightness of atrium walls are much brighter than the surfaces within the space and help to balance the brightness from perimeter windows. The floor area above 300 lux increases from 40% without skylights to 43% with 10% SFAR skylights. This increase in functional illumination may not justify the decision to introduce skylights as much as the improved visual brightness they provide.

These data represent the second floor of a 4-story atrium design and is exactly like the previous case except that 10% SFAR skylights are added. The floor plates are 35’ deep and atrium is the same width. This design meets the rule of thumb discussed in the ‘Overview’ above. It is clear from the illumination plot that the atrium design provides substantial functional illumination to the floor plate. The false color luminance image (top right) reveals that the surface brightness of atrium walls are much brighter than the surfaces within the space and help to balance the brightness from perimeter windows. The floor area above 300 lux increases from 68% without skylights to 71% with 10% SFAR skylights. This modest increase may not warrant the introduction of skylights, however that design decision cannot simply be made depending on the performance of the second floor. Furthermore, this modest increase suggests that if an improvement is going to be made, it will need to be via increased floor to ceiling height or by other means to allow more daylight from the atrium to enter the workspaces.