You can use a bedroom without windows or board up the windows to block out light and nosy people. Or if you want you can build a grow box in a room. for 15 plants you would'nt need a entire room so maybe the grow box construction might be for you however it'll take about $150.00 to build. Then you have equipment to buy still. I myself use a grow box when I grow and paint it the same color as the walls so it blends in well. I make it look like a pantry or extra storage space.