Cost-effective way to have good lighting for color-blind users
another solution that does not involve powered lighting could be to use 'Light Pipes' or 'Light Tubes' with 'Full' or 'Half' CTO (Colour Temperature Orange) filters clipped onto them inside the building.  

Colour temperature orange filters are used in the TV and Film industries to transform the light source into a warmer more incandescent type of light in terms of its colour.  These gels can also withstand high temperatures.

Google 'CTO Gels'.  Wikipedia also has a clear article on 'Light Tubes'.

To dim the light you could then place 'Neutral Density' lighting gels over the CTO sheets.  Alternatively louvered shutters over the ends of the light pipes would allow you to fine tune the amount of light getting through.  

The light pipe idea would mean free lighting after the install has been paid for and is a low tech but long term solution.