In the scene, the exposure had to be animated as different rooms in the scene had different lighting. If the exposure was the same throughout the animation, some of the rooms would be too dark and others too bright.
In order to animate the exposure, simply tick use simple (EV) and animate the value. This will animate the exposure so that the exposure will change through out the animation. This can be used to focus the exposure for different environments as the camera moves around the scene.
