I have had my sewing room in the basement for 20 years. I keep all my fabric down there and I have 5 of my sewing/quilting machines down there. I don't run a dehumidifier and have never had a problem. I have one window that is 3X 5 feet. I never feel like I need more natural light even at night. My hubby did a great job with the lighting when we redid my sewing room several years ago. Have fun and no worries!