Why is ARTCC room lighting in the US dim? I have made several trips to US ARTCC centers and they had very dim lighting. I was told the lighting, carpet and wall colors where all decided on by the (PATCO) union contract with the FAA. 

This week I was watching a BBC documentary and the British air route control room (NATS) was brighter than a normal office.

What is the justification between the two lighting preferences.



Dimly lit ARTCC room, even the display and control area use dark trim.



Brightly lit British NATS room, note the bright display and control area.
The FAA set out the ARTCC Facility Design Guidelines in this document. In short they are dark to minimize glare. 


  295. TRACON OPERATIONS ROOM. Lighting intensities in the TRACON operations room are usually kept at a very low ambient level, less
  than 5 foot-candles (fc), in order to prevent glare and reflection
  detracting from the target viewing on the radar displays. The design
  shall consider incandescent lighting with pinhole covers or framing
  capabilities in lieu of fluorescent lights. These incandescent lights
  can be aimed exactly where needed and, unlike fluorescent lights, can
  be dimmed to low light levels.


Its possible the British have no such requirement (under EASA or ICAO) or that the photo was simply over exposed and the room appears bright.