A series of 4’x6’ translucent (light diffusing) skylights with a 50% visible light transmission (Tvis) are organized in the roof of the entire atrium that represent 2.5% of the floor area intended to be daylit. These skylights wash diffused illumination on both vertical surfaces and completely eliminate any direct sun penetration. The character of the space is far more even on an annual basis due to the diffused aperture, which can be argued as more conducive to office work, or argued as less visually interesting and more monotonous. Since few view windows are provided, the careful inclusion of translucent glass in the clerestories shown previously could be argued to increase users’ connection with the outdoors. Approximately 5% of the office cubicle zone is above the 300 lux criteria. This value is lower than might be expected and can be explained by the remote relationship of the skylights to the task zone.

A 7’ tall 50% north-facing clerestory washes daylight on the wall adjacent to the office cubicles on the second floor. The area below the clerestory is dark by comparison, but the light redirecting ‘cloud’ next to the window serves to brighten the wall below the clerestory somewhat. The daylight is not reaching the office cubicles because they are tucked under a dropped ceiling section, however the circulation ways are well lit. Zero percent of the office cubicle zone is above the 300 lux criteria.

A 7’ tall 50% south-facing clerestory washes daylight on the north wall of the atrium while the light redirecting ‘cloud’ next to the window serves to push daylight into the office cubicle zone. Direct sun penetration is partly controlled by an external shading device while the open plan offices are set to the south side to avoid any direct sun that enters under the shading device. Direct sun does penetrate into the circulation way, however this is not a concern related to visual comfort in either the offices or the circulation way. In fact, the additional illumination provided by the direct sun penetration serves increase the perception of brightness across the entire space. Approximately 35% of the office cubicle zone is above the 300 lux criteria.

These data represent the effect of a series of 7’ tall clerestory windows facing both north and south. These apertures wash daylight on the opposing walls to create balanced brightness in the atrium. The area below the clerestories is illuminated by light from the opposite clerestory window and from the redirecting ‘clouds’ next to the windows. Direct sun penetration is controlled by an external shading device while the open plan offices are set to the south side to avoid any direct sun that enters under the shading device during winter months. Direct sun does penetrate into the circulation way during winter months, however this is not a concern related to visual comfort in either the offices or the circulation way. Approximately 50% of the office cubicle zone is above the 300 lux criteria.

These data represent a additional design consideration to improve the performance over the as designed condition. In this scenario, the throat of the atrium is widened in order to provide additional daylight to the workstations. This dramatically increases daylight illumination at the workstations but potentially creates concerns regarding glare due to the line of sight to the glass and potential low angle sunlight reaching objects near the workstations. However, upon inspection of simulations done at low winter sun angles, there are very few times of the year where direct sun penetration or line of sight to the disc of the sun is a concern. Approximately 74% of the office cubicle zone is above the 300 lux criteria.