RE: Matte white walls and the dark reflection

The basement of our house is in pretty bad shape, but it is dry, though will remain cold for some time to come. To brighten it up a little, we have been painting the very rough walls in a base white. It makes a big difference. We will also paint the floors when the time comes, which will clean it up enough to remove 60 years of grime and dust and make it a little more comfortable. The sauna and laundry are in the basement, so we use it often. Eventually, we will heat the floor, but that requires digging out the concrete floor completely and we do not have the funds for this at this time - and probably for a while.

@tarazkp, Finland's winter seems to be very cold. In winter, the basement will not be remodeled. Even if the basement is unfinished, your family will be able to spend a warm winter.