Slide baby slide!
In this illustration of the glazing control concept (simulating May 21 or July 21), the VLT of each glass pane is adjusted based upon where direct sunlight passing through that pane would strike within the space. Sunlight striking the work-plane 30″ above the floor causes the glass pane VLT to be set at 1% (red rays). Sunlight striking the lower wall area sets the glass VLT at 6% (orange rays), the upper wall 20% (yellow rays), and the high wall 60% (green rays). If the sunlight strikes none of these surfaces, the glass pane will also be left clear at 60% VLT. That control patterning is based on the control of direct sunlight. In addition, if at certain times the overall light levels including inter-reflected light would exceed the desired illuminance threshold, the algorithm would respond to reduce the glass VLTs accordingly.
Three views of May 21 / July 21st: Upper left shows the rays inside the space, darkness on the walls represents the zones of control; upper right shows the space from the exterior, and at bottom is a rendered set of images (transmissions and color are approximate and representational).
This program would only operate during sunny days in which direct sun hits the space. A photocell on the roof would watch for cloudy skys, and lighten the glass accordingly. Additional programs could also be accommodated, such as a weekend / after hours mode that drops the transmission to 1% across the roof.
This solution provides maximum flexibility across the space throughout the year, and a unique method for controlling daylight, utilizing the capability of the electrochromic glazing to provide a dynamic shading response precisely tailored to every current sun and sky condition.