Environmental Control Systems I
Architecture 591
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Vital Signs Case Study

******************** Data ********************

Light Transmittance
 

At 2:30 p.m. on Wednesday, November 17, 1999, a transmitted solar radiation of 176.38 W/m² was measured through the transparent glass.  With the mesh shade closed, the transmitted solar radiation was reduced to 13.39 W/m².  When the solid shade was closed, the transmitted solar radiation reduced to 0.01 W/m².
 

Light transmittance of the MESH SHADE = 7.59%

Light transmittance of the SOLID SHADE = 0.01%
 

Questionnaire Results
 

Illuminance Levels
All data are in footcandles (fcd).  Measurements were taken on the desktop surface, with the fluorescent lights on.
 

Subjective Data
 

            Subjective evaluation under overcast conditions:

• • Shades open:  Glare is noticeable, but not severe enough to be problematic.
  • Mesh shade closed:  Glare is completely eliminated; cannot see the reflection of the window on the screen.
  • Opaque shades closed:  No glare.
  • Noticeable glare was caused by the overhead fluorescent lights on every monitor except for those in the back row.
  • Because of the height and tilt of the monitors, the position of the windows, and the overhead lights, the amount of glare varies with the height of the observer.  In general, shorter people experience more glare.

  
  Subjective evaluation under sunny conditions:
   

  • Shades open:  Glare is a severe problem.  The computers in the back row cannot be used.
  • Mesh shade closed:  Glare is still a very severe problem.
  • Opaque shades closed:  Glare problem eliminated.

  
  Subjective evaluation under night time conditions:
   

  • Regardless of shade position, glare from outside is obviously not a factor.  Some glare is still experienced from the overhead fluorescent lights.
  • Outside lights did not cause glare on the computer screens.

  
   

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