Water base finishes darken the least, windows with Low E will retrard
suns effects dramaticly. I cant say for wood but oak is oak, teak is
nicer in looks and is darker to start with. Never heard of Kempas. My
red oak south facing with area rugs has not changed color even under
rugs in 14 years . My glass filters most of the harmfull rays. Glass and
finish are key.