Willeke, all your indoor plants will do better with some air-movement. In my opinion, it really won't help much to simply open a window unless there happens to be a good breeze blowing through that window. You should easily be able to find a very small, very inexpensive fan either at a department store or online. My experiences, growing tropical plants in greenhouses and now in a solarium, clearly demonstrate the importance of air-movement. I am absolutely convinced that my extensive use of fans pretty much eliminates insect and disease problems. Depending on the time of year, I have anywhere from 800 to 1000 tropical plants to care for.