We also painted our house in color. For us with a brightness reference value of 77. We also have several white accents (fascias, etc.) and the contrast is quite noticeable. In daylight, I would still describe the color as quite light, but at dusk it is clearly set apart from white. Maybe google "Fassaden Konfigurator". Right the first entry from a larger manufacturer with Cap**** you can take a pretty good look at it.