The only light that can go into the basement is from the sky. No street light, no traffic, no neighbors.
I have a Thomas safe light with all the filters, but I never hang it up. I know the darkroom well and I can work in the dark.
My concern is between the time I open the paper box and bag, take out one paper and feed it onto the easel. Then set it up in the print drum. The total time in the darkroom is about 1 minute (exposure time included).
The reason I do not seal off the windows is that, I want some air circulation at the time I'm not in basement.