On Fri, 28 May 2021 19:10:38 +0100, Dave W
wrote:

snip

As your window glass will have attenuated the light a lot, the best
you could do, short of putting it outside with some proper covering,
would be to stick it to the wundow without any extra covering, sealed
so that dust can't get in.

Ah, now there is a bit of out of the box thinking. ;-)

Yes, it would be easy to print a small box with a reasonable (~5mm)
flange and simply stick it to the inside of the window (facing out
etc) with some double sided tape. If I leave a some ventilation
underneath it shouldn't fog etc.

I could have two, one 'looking' outside and one monitoring the ambient
light levels in say the hall.

Cheers, T i m