The lower level would not include any light-related installation.  For the Google Doodle to be projected onto the exterior of the bridge on this level, one-way glass facing the OUTSIDE would be needed so that Google employees would not be seeing a weird, mirrored Doodle.  Instead, the interior would be full of diffuse light, and climate-controlled to match the weather at the Google office which was currently experiencing the most "ideal" weather, or the weather closest to sunny and 75!  

This section of the bridge would be outfitted with the capability to blow a warm breeze on its occupants, but only when the occupant was moving through the space!  In addition, the ceiling would be a reflection of the blues and greens from the floor above, but diffuse as if it was a calming sky.  These elements, plus plant life and natural-feeling light, would encourage calmness and provide a meditative space for stressed-out Google employees.