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Description:
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This research developed the Optical Light Pipe (OLP ) as a feasible solution to
solve the problem of insufficient daylighting in deep plan office spaces for predominantly
sunny climates . It further combined the OLP with a Specular Light Shelf
(SLS ) to achieve uniform daylighting .
This research was performed with an experimental setup of two 1 :4 scale models
of deep plan office spaces , modified from an earlier research on optical light pipe at
College Station , TX . Blinds and shading devices were installed on the south façade to
provide daylight to the front zone of a 20 feet by 30 feet office module . The back zone
was daylit by the OLP hidden in the plenum . The existing OLP design was optimized
through computer aided ray -tracing . The SLS design was based on an earlier prototype
designed at Lawrence Berkeley National Labs (LBNL ) .
Results were based on observations made on clear and cloudy sky days between
February 3rd and March 17th . The OLP achieved more than 300 lux of average
workplane illuminance for 7 .4 hours , when global horizontal illuminance was greater
than 40 ,000 lux . It also achieved 200 lux of illuminance higher than an earlier prototype (Martins -Mogo , 2005 ) on workplane between 1000hrs and 1630hrs . It exhibited a glare
free daylight distribution with luminance ratios well within prescribed limits on most of
the vertical surfaces , with a relatively uniform illuminance distribution on back
taskplane . OLP was better than windows with blinds and shading at providing diffuse
daylight in backzone on a cloudy day , when global horizontal illuminance was greater
than 20 ,000 lux .
The OLP used in combination with SLS achieved more than 500 lux of average
workplane illuminance for 6 hours , when global horizontal illuminance was greater than
40 ,000 lux . SLS also produced more uniform illuminance levels on the workplane at all
times and on the leftwall at most times . However , it produced non -uniform luminance
distribution on walls and ceiling and luminance ratios higher than allowable limits on the
sidewall for some morning hours , and hence needed further refinement in design . |