My sister has a reading room in her house. When her kid moved out for college, she converted his room into a little library, with bookshelves covering every wall floor to ceiling, and a nice little comfy chair and coffee table in the middle. It is a nice little spot to hang out, but she is always weird about anyone else being in there but. If I need to borrow a book, she will get it for me, and she never asks anyone to come in there with her. I thought it was just about it being “her” space, but it turns out that it’s about the HVAC situation, and her concerns about air quality. I don’t know how valuable these books are on the open market, but they are valuable to my sister, and she knows it takes good air quality to maintain them. A lot of these books came from out grandparents, and are a hundred years old, so she leaves the dehumidifier running at all times. She keeps the door shut, the air vents open, and the dehumidifier on to try and keep a steady, consistent air quality in the room. This is why she doesn’t want other people coming in and out, because it pollutes the air quality. For Christmas this year I am going to get her an HVAC upgrade for the room. It is a special air purifier that has a built-in dehumidifier, and is supposed to use air filters and UV light to radically reduce airborne bacteria as well as moisture. She is going to love it!