Ideal Environment for Chinchillas
Chinchillas will be happiest when you provide an environment that meets their needs and doesn't cause unnecessary stress.
By their nature, they don't like loud noises or a lot of movement. Such things will scare them causing them to remain in their cage. Even something seemingly innocent as a rain shower can seem scary to a chinchilla. As such, you'll want to keep them away from young children and other pets.
Although chinchillas can live in a cage, they will be healthiest if given a room or hallway to run in for a few hours each night. This gives them an opportunity to explore and to get some exercise beyond what a wheel can provide. Ideally, their cage should be up against a wall or in a corner. Doing so will provide your chinchillas a sense of safety especially if their sleeping box is also in the corner with the opening facing the wall.
Speaking of wheels, every chinchilla cage should have one. Getting a wheel big enough for a chinchilla can take a little searching, but they do exist. We prefer wheels that are solid so that our chinchilla's feet don't slip through the bars.
Being from the Andes, chinchillas are used to cooler temperatures. In fact, they can die if the temperature gets too high partly because they can't sweat to cool themselves. A good rule of thumb is to add the humidity and temperature together. This number should never exceed 150. We try to keep our chins in a room that doesn't exceed 75 degrees. This gives us a little buffer.
Chinchillas also like to chew on things. This includes doors, baseboards, and wires. Be sure to protect these areas with cardboard, wood, or plastic.
And finally, since chinchillas are crepuscular, you should keep them in an area during the day where they can sleep. No need to keep them in the dark. In fact, daylight will allow them to sense when to go to sleep and when to wake up.