Spiritually, any sort of experience that brings about a sense of emptiness signifies the Void.
Psychological / Emotional Perspective:
We may need space to be ourselves in order to come to terms with what is occurring in our lives. To be in an empty house or building denotes the fact that we have left behind old attitudes and habits.
Everyday Material Aspects:
To experience emptiness in a dream indicates there is a lack of pleasure and enthusiasm. We could be suffering from a sense of isolation, or perhaps of not having anything to hold on to. We may have had expectations that cannot be realized.
You might like to consult the entries for Abyss and Void.