Just to add, I just checked the main room of the house, and where I have a painting on the wall, even on a sunny day it is only 50lux.
Using the 24MLH as an example that is
50lux x 12hours = 600LuxH
600 x 365days = 219,000 LuxH a year
24,000,000 / 219,000 = 110 years.
I now understand why...