There are many things to consider when you have a painting that you want to keep in good condition. Two of the most important factors are temperature and humidity. When thinking of the environment for your work of art, it is best to think of museums and the lengths taken to regulate conditions to maintain historical works.
Caring for Your Paintings is a great article from the Smithsonian Museum Conservation Institute. These experts cover the most important factors into caring, hanging and maintaining paintings. A great read for anyone who owns or cares for fine art.