:smoking: hey EQ'.... sure mate, cough up the quid for the AC power bill! Alas, there's no work around for it, either the T and RH% are in proper range, or you're in the compromise zone,... when I had those suboptimal high T/RH conditions, I did up the airflow some,.. as you know, RH and T are so tightly linked, you can't adjust one without causing changes in the other,...
I don't think pitch dark is necessary, I can't get that either drying in a room.... Low light won't hurt anything IMO, but definitely no direct Sunlight or even bright light are what I hear,...